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H_2CO and H110α survey toward UCHII regions

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Research in Astronomy and Astrophysics 2011年第2期11卷 156-162页

作者： Xiao-Hong Han graduate university of chinese academy of sciences, beijing 100049, china National Astronomical Observatories / Urumqi Observatory Chinese Academy of Sciences Urumqi 830011 China graduate university of chinese academy of sciences Beijing 100049 China

We report results of the H2CO and H110α survey toward 281 UCHII regions using the Urumqi 25m radio *** obtained 37 new H2CO detections,and H110α was simultaneously detected in eight of *** H110α was detected in another UCHII *** calculated kinematic distances of nine UCHII regions with the detected H110α and resolved the kinematic distance ambiguity for six of *** detection rate of H2CO of our observation was 13.2%,which is low compared with one of the other *** possible reason is that the sensitivity of our telescope is relatively low.

关键词： ISM: HII regions -- ISM: molecules -- radio lines: ISM

Applications of URANS on predicting unsteady turbulent separated flows

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Acta Mechanica Sinica 2009年第3期25卷 319-324页

作者： Jinglei Xu Huiyang Ma Department of Physics, graduate university of the chinese academy of sciences, 100049 beijing, china Department of Physics Graduate University of the Chinese Academy of Sciences 100049 Beijing China

Accurate prediction of unsteady separated turbulent flows remains one of the toughest tasks and a practi cal challenge for turbulence modeling. In this paper, a 2D flow past a circular cylinder at Reynolds number 3,900 is numerically investigated by using the technique of unsteady RANS （URANS）. Some typical linear and nonlinear eddy viscosity turbulence models （LEVM and NLEVM） and a quadratic explicit algebraic stress model （EASM） are evaluated. Numerical results have shown that a high-performance cubic NLEVM, such as CLS, are superior to the others in simulating turbulent separated flows with unsteady vortex shedding.

关键词： URANS Nonlinear eddy viscosity turbulencemodel ,Separated flows Circular cylinder

湖南地区汉族人群中HLA-A、B、DRB1等位基因与原因不明习惯性流产相关性研究

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现代免疫学 2009年第6期29卷 497-500页

作者：钱小兵程腊梅谢毓滨周佳金文静卢光琇中国科学院研究生院北京100049 人类干细胞国家工程研究中心长沙410078 中南大学生殖与干细胞工程研究所长沙410078 长沙血液中心长沙410001

探讨HLA-A、-B和-DRB1位点等位基因多态性与原因不明习惯性流产的相关性。应用PCR-SSP方法对175对(350例)湖南汉族原因不明习惯性流产(URSA)患者夫妇进行HLA-A、-B、-DRB1基因分型,并以2 000例(男女各1 000例)湖南无关健康汉族个体造血... 详细信息

探讨HLA-A、-B和-DRB1位点等位基因多态性与原因不明习惯性流产的相关性。应用PCR-SSP方法对175对(350例)湖南汉族原因不明习惯性流产(URSA)患者夫妇进行HLA-A、-B、-DRB1基因分型,并以2 000例(男女各1 000例)湖南无关健康汉族个体造血干细胞分型资料作为对照,分析HLA等位基因频率在两组中的分布差异。结果是HLA-A、-B及-DRB1位点各等位基因频率在对照组男女中均无显著差异(P>0.05);URSA患者组A*31(2.86%)、B*08(0.86%)、B*39(4.14%)和B*56(1.86%)的等位基因频率显著高于对照组(RR值分别为2.07、2.99、1.56和2.19;P值分别为0.0059、0.0276、0.0404和0.0172);在URSA妻子组中,B*39(4.57%)显著高于对照组(RR=1.75;P=0.0474),A*33(3.71%)、B*58(3.14%)和DRB1*03(2.29%)的等位基因频率明显低于对照组(RR值分别为0.57、0.51和0.50;P值分别为0.0339、0.0182和0.0383);A*31(3.14%)、B*08(1.43%)、B*52(2.29%)及B*56(2.29%)在URSA丈夫组中的等位基因频率均高于对照组(RR值分别为2.32、5.08、2.31和2.77;P值分别为0.013、0.0012、0.0374及0.0105)。结果表明湖南汉族人群中A*31、B*08、B*39、B*52和B*56可能是URSA的易感等位基因,而A*33、B*58和DRB1*03可能对URSA的发生有保护作用。

关键词：原因不明习惯性流产人类白细胞抗原等位基因频率

A 12-bit multichannel ADC for pixel detectors in particle physics and nuclear imaging

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Science china(Technological sciences) 2010年第5期53卷 1208-1214页

作者： WEI Wei1,2,3,WANG Zheng1,3 & ZHAO JingWei1,3 1 Institute of High Energy Physics,chinese academy of sciences,beijing 100049,china 2 graduate university of chinese academy of sciences,beijing 100049,china 3 Key Lab of Nuclear Detection Technology and Nuclear Electronics of chinese academy of sciences,beijing 100049,china 1. Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China2. Graduate University of Chinese Academy of Sciences Beijing 100049 China3. Key Lab of Nuclear Detection Technology and Nuclear Electronics of Chinese Academy of Sciences Beijing 100049 China

Modern pixel detectors in nuclear and particle physics experiments and also in nuclear imaging,starve for highly integrated application specified integrated circuit(ASIC),whereas in china the study of ASIC still stays far away from practical *** lack of ASIC strictly limits the research and development of domestic high energy physics field.A 12-bit multichannel ADC designed for high density readout is introduced as a major candidate for solution.A precise model is discussed and the simulation fully agrees with the model,which indicates a key principle of *** is performed according to the given rule,and novel layout techniques are carried *** results in all aspects are also obtained,showing an excellent real performance,which satisfies the practical requirement.

关键词： application specified integrated circuit high density readout Wilkinson ADC multi-channel ADC

Structure of augmentation quotients of finite homocyclic abelian groups

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Science china Mathematics 2007年第9期50卷 1280-1288页

作者： Guo-ping TANG School of Mathematical sciences,graduate university of chinese academy of sciences,beijing 100049,china 1. School of Mathematical sciences Graduate University of Chinese Academy of Sciences Beijing 100049 China

Let G be a finite abelian group and its Sylow p-subgroup a direct product of copies of a cyclic group of order p r , i.e., a finite homocyclic abelian group. Let Δ n (G) denote the n-th power of the augmentation ideal Δ(G) of the integral group ring ?G. The paper gives an explicit structure of the consecutive quotient group Q n (G) = Δ n (G)/Δ n+1(G) for any natural number n and as a consequence settles a problem of Karpilovsky for this particular class of finite abelian groups.

关键词： integral group ring augmentation ideal consecutive quotient of augmentation ideal 16S34 20C05

Observation results of relativistic electrons detected by Fengyun-1 satellite and analysis of relativistic electron enhancement (REE) events

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Science china(Physics,Mechanics & Astronomy) 2008年第12期51卷 1947-1956页

作者： YANG XiaoChao1,2↑ & WANG ShiJin1 1 Center for Space Science and Applied Research, chinese academy of sciences, beijing 100190, china 2 graduate university of chinese academy of sciences, beijing 100049, china 1. Center for Space Science and Applied Research Chinese Academy of Sciences Beijing 100190 China 2. graduate university of chinese academy of sciences Beijing 100049 China

The space particle component detector on Fengyun-1 satellite which works at the sun-synchronous orbit of about 870 km altitude has detected relativistic electrons for a long time. In comparison with the SAMPEX satellite observations during 1999–2004, the relativistic electron data from Fengyun-1 satellite from June 1999 to 2005 are used to analyze the relativistic electron enhancement (REE) events at the low earth orbit, and the possible correlation among REE events at the low earth orbit, high-speed solar wind and geomagnetic storms is discussed. The statistical result presents that 45 REE events are found in total during this time period, and the strong REE events with the maximum daily average flux > 400 cm?2·srt-1·s?1 occur mostly during the transition period from solar maximum to solar minimum. Among these 45 REE events, four strong REE events last a longer time period from 26-to 51-day and correlate closely with high speed solar wind and strong geomagnetic storms. Meanwhile, several strong geomagnetic storms occur continuously before these REE events, and these continuous geomagnetic storms would be an important factor causing these long-lasting strong REE events. The correlation analysis for overall 45 events indicates that the strength of the REE events correlates with the solar wind speed and the strength of the geomagnetic storm, and the correlation for strong REE events is much stronger than that for weak REE events.

关键词： relativistic electron enhancement low earth orbit high-speed solar wind geomagnetic storm

Ionization state of cosmic hydrogen by early stars and quasars

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Research in Astronomy and Astrophysics 2009年第6期9卷 665-681页

作者： Xiao-Chun Mao1,2 1 National Astronomical Observatories, chinese academy of sciences, beijing 100012, china 2 graduate university of chinese academy of sciences, beijing 100049, china National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China graduate university of chinese academy of sciences Beijing 100049 China

Cosmic hydrogen is reionized and maintained in its highly ionized state by the ultraviolet emission attributed to an early generation of stars and quasars. The Lyα opacity observed in absorption spectra of high-redshift quasars permits more stringent constraints on the ionization state of cosmic hydrogen. Based on density perturbation and structure formation theory, we develop an analytic model to trace the evolution of the ionization state in the post-overlap epoch of reionization, in which the bias factor is taken into account. For quasars, we represent an improved luminosity function by utilizing a hybrid approach for the halo formation rate that is in reasonable agreement with the published measurements at 2 ≤ z ≤ 6. Comparison with the classic Press-Schechter mass function of dark matter halos, we demonstrate that the biased mass distribution indeed enhances star formation efficiency in the overdense environment by more than 25 per cent following the overlap of ionized bubbles. In addition, an alternative way is introduced to derive robust estimates of the mean free path for ionizing photons. In our model, star-forming galaxies are likely to dominate the ionizing background radiation beyond z = 3, and quasars contribute equally above a redshift of z ～ 2.5. From 5 ≤ z ≤ 6, the lack of evolution in photoionization rate can thus be explained by the relatively flat evolution in star formation efficiency, although the mean free path of ionizing photons increases rapidly. Moreover, in the redshift interval z ～ 2 - 6, the expected mean free path and Gunn-Peterson optical depth obviously evolve by a factor of ～ 500 and ～50 respectively. We find that the relative values of critical overdensities for hydrogen ionization and collapse could be 430% at z ≈2 and 2% at z ≈6, suggesting a rapid overlap process in the overdense regions around instant quasars following reionization. We further illustrate that the absolute estimates of the fraction of neutral hydrogen computed fr

关键词： cosmology theory -- formation galaxies -- quasars general -- diffuse radiation -- intergalactic medium

Infrared Galaxies in the Nearby Universe

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chinese Journal of Astronomy and Astrophysics 2008年第6期8卷 643-652页

作者： Jian-Ling Wang 1 National Astronomical Observatories,chinese academy of sciences,beijing 100012,china 2 graduate School of chinese academy of sciences,beijing 100049,china National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China graduate School of chinese academy of sciences Beijing 100049 China

We used the Sloan Digital Sky Survey （SDSS） Data Release 5 （DR5） to study the morphological properties of 1137 nearby infrared （IR） galaxies, most of which are brighter than 15.9 mag in r-band. This sample was drawn from a cross-correlation of the Infra-Red Astronomical Satellite （IRAS） point source catalog redshift survey with DR5 at z ≤ 0.08. Based on this IR galaxy sample, we constructed five volume-limited sub-samples with IR luminosity ranging from 10^9.5 L⊙ to 10^12L⊙. By deriving the IR luminosity functions （LF） for different morphological types, we found that normal spiral galaxies are the dominant population below LIR ~ 8 ~ 10^10 L⊙; while the fraction of barred spiral galaxies increases with increasing IR luminosity and becomes dominant in spiral galaxies beyond LIR ≈ 5 × 10^10L⊙. As the IR luminosity decreases, the IR galaxies become more compact and have lower stellar masses. The analysis also shows that normal spiral galaxies give the dominant contribution to the total comoving IR energy density in the nearby universe, while, in contrast, the contribution from peculiar galaxies is only 39%.

关键词： galaxies evolution galaxies interactions galaxies starburst infrared galaxies galaxies luminosity function

Research on applying physical chaos generator to spacecraft information security

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Science china(Technological sciences) 2009年第5期52卷 1463-1470页

作者： ZHAO HePing State Key Laboratory of Information Security,graduate university of chinese academy of sciences,beijing 100049,china china academy of Space Technology,beijing 100094,china State Key Laboratory of Information Security Graduate University of Chinese Academy of Sciences Beijing 100049 China china academy of Space Technology Beijing 100094 China

The effectiveness of a short-length message extension method based on physical chaos generator was analyzed and the entropy of the extended message was calculated in this *** analysis demon-strated that with the mentioned method the entropy of short-length messages,which are repeatedly used in spacecraft data systems,is obviously increased,and the security of transmission is enhanced as *** paper also presented an improvement of the protocol for secret key agreement presented by *** and *** of depending on characteristics of communication channel,this method takes advantage of the random data produced by physical chaos generator to preset the initial parameters of the procedure on both sides of communication,so that the procedure and quantity of cipher key can be precisely *** method can be used to cipher key management of se-cure communication between long life-span spacecraft and ground system.

关键词： physical chaos generator spacecraft information security message extension cipher key management