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Research in Astronomy and Astrophysics 2012年第8期12卷 865-890页

作者： Xiaohui Fan Kavli institute for Astronomy and Astrophysics, Peking University, beijing 100871, china Steward Observatory, The University of Arizona, Tucson, 85721, USA Kavli institute for Astronomy and Astrophysics Peking University Beijing 100871 China Steward Observatory The University of Arizona Tucson 85721 USA

Studying the first generation of stars, galaxies and supermassive black holes as well as the epoch of reionization is one of the fundamental questions of modern as- trophysics. The last few years have witnessed the first confirmation of the discoveries of galaxies, quasars and Gamma-Ray Bursts at z 〉 7, with possible detections at z - 10. There is also mounting evidence that cosmic reionization is a prolonged pro- cess that peaks around z - 10 and ends at z- 6 - 7. Observations of the highest redshift intergalactic medium and the most metal-poor stars in the Galaxy begin to constrain the earliest chemical enrichment processes in the Universe. These observa- tions provide a glimpse of cosmic history over the first billion years after the Big Bang. In this review, we will present recent results on the observations of the high-redshift Universe over the past decade, highlight key challenges and uncertainties in these observations, and preview what is possible with the next generation facilities in studying the first light and mapping the history of reionization.

关键词： galaxies: evolution -- galaxies: formation -- galaxies: high-redshift-- intergalactic medium -- quasars: general -- cosmology: large-scale structure ofuniverse

STRAIN　INDUCED　STRUCTURAL　TRANSITION　OF　INTERFACES　AND　TWINS　IN　A　HOT－DEFORMED　DUAL－PHASE　TIAL　ALLOY

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Acta Metallurgica Sinica(English Letters) 1995年第Z1期8卷 273-286页

作者： CHEN GuoFiang WANG Jinguo ZHANG Lichun and YE Hengqiang(State Key Laboratory for Advanced Metals and Materials, University of science and Technology beijing, beijing, 100083, P. R. china Laboratory of Atomic Imaging of Solids, institute of Metal Researc beijing Univ of science and Technology Beijing China

The structure characteristics of a2/γinterfaces and the features of deformation twins in a quasi-isothermal forged Ti-45Al-10Nb alloy were studied by highresolution transmission electron microscopy. Three types of strain induced a2/γinterfaces and two types of strain induced twin boundaries were identified The most,important features are high density of ledges and the existence of I/3[111] Frank partial dislocation. Mechanisms for the formation these interfaces were proposed Two types of deformation twins were observed These deformation twins always start from the ledges it seems that ledges at interfaces are important features of interfacial structure for the mechanical behavior of alloys.

关键词： strain induced structural transition interfacial structure,deformation twins intermetallic TiAl alloy HREM

Speed Sensorless Control of a Linear Synchronous Motor using State Observer On d-q Reference Frame

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Speed Sensorless Control of a Linear Synchronous Motor using...

Features of the middle-and low-latitude ionosphere during solar minimum as revealed from COSMIC radio occultation measurements

11th International Conference on Electrical Machines and systems

作者： Xiaoxin Wang~(1*) Qiongxuan Ge~1 1 institute of Electrical Engineering chinese academy of sciences china

＜正＞Ⅰ.INTRODUCTION Many sensorless methods have been proposed for LSM. Most of them are based on estimation of EMF on stationaryα-βreference frame to get the rotor *** the EMF is proportional to the mover’s speed,it is impossible to estimate the position for low speed *** voltage and curre- nt include harmonic content,the estimation is not accurate. Some other algorithms have been developed based on d-q synchronous rotative reference *** kind of methods can avoid harmonic disturbance and estimate lower speed.

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Features of the middle-and low-latitude ionosphere during so...

Influence of some factors on alpha energy spectrum of^(241)Am fire alarm source

中国科学院地质与地球物理研究所第11届（2011年度）学术年会

作者： Libo Liu,Huijun Le,Yiding Chen,Maosheng He,Weixing Wan,and Xinan Yue 1 beijing National Observatory of Space Environment,institute of Geology and Geophysics,chinese academy of sciences,beijing,china. 2 Also at State Key Laboratory of Space Weather,Center for Space science and Applied Research,chinese academy of sciences,beijing, china. 3 COSMIC Program Office,University Corporation for Atmospheric Research,Boulder,Colorado USA.

[1]In this study,the ionospheric electron density profiles retrieved from radio occupation measurements of the Constellation Observing System for Meteorology,Ionosphere and Climate(COSMIC) mission are analyzed to determine the F layer maximum electron density(NF),peak height(hF),and Chapman scale height(H).During the deep solar minimum of 2008-2009,NF,hF,and H show complicated seasonal variations,which are generally consistent with those in previous solar *** the equinoctial asymmetry,nonseasonal and semiannual anomalies are present in daytime NF;the Weddell Sea anomaly appears in nighttime NF in all seasons except the June solstice. Unusually higher values of hF and Hm appear at southern middle latitudes in the region centered at 70°E in the daytime and hF at 70°W in the ***-like longitudinal patterns are evidently present at low latitudes in all three parameters,showing diurnal and seasonal *** values of the parameters under study are smaller in 2008-2009 than the rest of the COSMIC period examined in this *** seasonal and latitudinal pattern of daytime NF on the solar sensitivity not only confirms our earlier investigation but also explains the observed small NF in 2008-2009 in response to the reduced solar extreme ultraviolet radiance.

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Nuclear science and Techniques 1999年第1期10卷 11-13页

作者： FENG Gensheng FENG Xinzhan LI Shujuan (china institute of Atomic Energy, beijing 102413) china institute of Atomic Energy Beijing 102413 China

Several primary factors influencing the alpha energy spectrum of 241Am fire alarm source have been studied in order to get better alpha energy spectrum. The results show that the homogeneity and the thickness of metal surface coat and the size of active area of the source have considerable influence on the alpha energy spectrum of the source.

关键词：火警 241Am警报源 α-能谱

Silicon-rutile - an ultra-high pressure (UHP) mineral from an ophiolite

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Progress in Natural science:Materials International 2003年第7期 50-53页

作者： YANG Jingsui , BAI Wenji, FANG Qingsong, YAN Binggang, SHI Nicheng, MA Zhesheng, DAI Mingquan and XIONG Ming (1. institute of Geology, chinese academy of Geological sciences, beijing 100037, china 2. Geological University of china, beijing 100083, china) institute of Geology Chinese Academy of Geological Sciences Beijing 100037 China Geological University of china Beijing 100083 China

Silicon(Si)-rutile separated from the Luobusa podiform chromitite in the Yarlung Zangbo ophiolite of southern Tibet is typically about 50 μm × 50 μm × 200 μm in size and consists mainly of SiO2 and TiO2- The average mineral formula is (Ti0. 82Si0.18)O2. Powder X-ray diffraction data show that it is tetragonal in form, and the unit cell dimensions and other parameters are: α= 4. 591(2) A , c = 2.946(2)A, v=62.09(5)A3, c/α=0.6415, with a molar volume about 5 % smaller than rutile (JCPDS, 21-1276). The Si4 + ions in silicon rutile are six-coordinated, and are substituted for Ti + in the rutile structural sites. The Si-rutile, along with other associated ultra-high minerals discovered in the chromitite, such as octahedral silicate, silicon-magnesium spinel (Si4+ ions are six-coordinated), diamond, and intergrown of SiO2 and FeO phases, probably originated from the transition zone or the lower mantle, and were brought to shallow levels beneath an oceanic spreading ridge by an upwelling superplurne.

关键词： Si-rutile UHP minerals ophiolite lower mantle chromitite.

IMPACTS OF FLOOD EVENTS IN COARSE SEDIMENT-PRODUCING AREAS ON CHANNEL SILTATION AND FLUVIAL PROCESS OF THE LOWER YELLOW RIVER

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International Journal of Sediment Research 2007年第2期22卷 142-149页

作者： Ou-yang ZHANG1, Xiufu FENG2 and Jiong-xin XU31 Bureau of Hydrology, Changjiang Water Resources Commission, Hubei, Wuhan 430010, china2 Chengdu University of technology, Sichuan, Chengdu 610059, china3institute of Geographic sciences and Natural Resources Research, CAS, beijing 100101, china Changjiang Water Resources Commiss Bureau Hydrol Wuhan 4310010 Peoples R China Chengdu Univ Technol Chengdu 610059 Peoples R China chinese Acad Sci Inst Geog Sci & Nat Resources Res Beijing 100101 Peoples R China

The method of multiple regression is used to analyze the influences of flood events from the coarse sediment producing areas on the channel siltation and fluvial process of the lower Yellow River based on the flood events from 1950 to 1985. The results showed that the flood events from the coarse sediment producing areas carry larger amounts of sediment load and coarser particle sizes than from other source areas, which increases deposition in the lower river channel. And there exist good correlations between channel siltation of the lower reaches of the Yellow River and the coming water and sediment of flood events from the coarse sediment producing areas. Through these correlations, the amounts of sediment deposition in the lower river channel could be roughly estimated based on the runoff and sediment load of flood events from the coarse sediment producing areas. The sediment deposition caused the fluvial process. There exists a complex response of channel form change to the coming water and sediment load of flood events from the coarse sediment producing areas. When the sediment concentration is smaller than 200kg/m3, the ratio between wide-depth ratio after flood and wide-depth ratio before flood((B/h)a / (B/h)b) will increase with the increase of the maximum sediment concentration; when the sediment concentration is near 200kg/m3, (B/h)a / (B/h)b reaches the maximum value; and when the sediment concentration reaches the limits of hyperconcentrated flow, (B/h)a / (B/h)b will decrease with the increase of the maximum sediment concentration. Generally, flood events from the coarse sediment producing areas made channel form of the lower Yellow River deeper and narrower, but a large amount of sediment deposition simultaneously occurs. So, the impacts of flood events from the coarse sediment producing areas on the channel of the lower Yellow River are lessened.

关键词： Channel siltation Fluvial process Coarse sediment-producing areas Flood events Yellow River basin

A new method of fabricating strained Silicon materials

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Rare Metals 2006年第z2期25卷 41-44页

作者： YANG Zongren LIANG Renrong XU Jun institute of Microelectronics Tsinghua University Beijing 100084 China Institute of Microelectronics Tsinghua University Beijing 100084 China Microelectronics and Nanoelectronics Division of the Tsinghua National Lab for Information Science and Technology Beijing 100084 China institute of Microelectronics Tsinghua University Beijing 100084 China

Strain-relaxed SiGe virtual substrates are of great importance for fabricating strained Si materials. Instead of using graded buffer method to obtain fully relaxed SiGe film, in this study a new method to obtain relaxed SiGe film and strained Si film with much thinner SiGe film was proposed. Almost fully relaxed thin SiGe buffer layer was obtained by Si/SiGe/Si multi-structure oxidation and the SiO2 layer removing before SiGe regrowth. Raman spectroscopy analysis indicates that the regrown SiGe film has a strain relaxation ratio of about 93% while the Si cap layer has a strain of 0.63%. AFM shows good surface roughness. This new method is proved to be a useful approach to fabricate thin relaxed epilayers and strain Si films.

关键词： strained Si SiGe oxidation strain relaxation

Study on Surface Free Energy of Thermochromic Wood

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chinese Forestry science and Technology 2010年第1期9卷 60-66页

作者： LIU Zhijia FU Feng BAO Fucheng Research institute of Wood Industry, chinese academy of Forestry, beijing 100091, P.R.china

Thermochromic wood is a kind of new functional materials. It is significant for thermochromic wood development to study surface free energy. Samples of chinese white poplar were colored using thermochromic agent though the method of ultrasonic impregnation and its surface free energy was investigated in the experiment. The results showed that the surface free energy for untreated, black-red, orange-yellow and blue thermochromic wood was 40.25, 29.85, 28.30 and 21.05 mN/m, respectively. The FTIR results showed that both the type and the number of function groups resulted in the change of free energy for untreated and thermochromic wood.

关键词： thermochromic wood free energy function group contact angle