CARBON DYNAMICS OF WETLAND IN THE SANJIANG PLAIN

1INTRODUCTIONWetlandsplayanimportant roleintheprocessofcar-bonstorage.Thetotalcarbonstoredindifferentkindsofwetlandsisabout15%-35%ofthetotalcarboninthegloballandsoils(POSTetal.,1982;GORHAM,1991).Inaddition,wetlandsaresignificantnaturalsources fortheatmospheric CH4 (MOORE,1994).It isestimatedthatabout110×1012gCH4 originates fromanaerobicdecompositioninthenaturalwetlands,CH4 emission fromthenaturalwetlandsis15%-30%oftheglobalCH4 emission andtheCH4 emission from thepeat land at hi…     

CPLD技术及其在现代时统中的应用

对CPLD(复杂可编程逻辑器件)技术的基本特征和发展趋势作了简要介绍,揭示了该技术在现代数字系统中的重要地位及作用.利用CPLD对时统设备IRIG-B码产生器进行集成,其实验结果表明,集成了的B码产生器不但简单、可靠,而且便于调试,克服了以往硬件电路复杂的缺点.     

疏散星团的最新研究进展

疏散星团在天文学和天体物理学研究中有着多方面的重要性。近年来在观测和理论工作上都取得了显著的进展。综述了疏散星团的研究现状，对成员判别、基本参数确定、团与恒星的演化、团的结构和动力学进行了详细评述。     

Effect of spatial variation characteristics on contouring of design storm depth

The ordinary kriging method, a geostatistical interpolation technique, was applied for developing contour maps of design storm depth in northern Taiwan using intensity–duration–frequency (IDF) data. Results of variogram modelling on design storm depths indicate that the design storms can be categorized into two distinct storm types: (i) storms of short duration and high spatial variation and (ii) storms of long duration and less spatial variation. For storms of the first category, the influence range of rainfall depth decreases when the recurrence interval increases, owing to the increasing degree of their spatial independence. However, for storms of the second category, the influence range of rainfall depth does not change significantly and has an average of approximately 72 km. For very extreme events, such as events of short duration and long recurrence interval, we do not recommend usage of the established design storm contours, because most of the interstation distances exceed the influence ranges. Our study concludes that the influence range of the design storm depth is dependent on the design duration and recurrence interval and is a key factor in developing design storm contours. Copyright © 2003 John Wiley & Sons, Ltd.     

成团天体系统成员概率计算的有效性问题

本文提出了一个普适的衡量成团天体系统成员概率计算结果的有效性指数：Ｅ＝１－ＮΣ｛Ｐ（ｉ）［１－Ｐ（ｉ）］｝／ΣＰ（ｉ）Σ［１－Ｐ（ｉ）］｝，并以此对以Ｓａｎｄｅｒｓ方法为基础的各种成员确定模型的有效性进行了分析．从总体上说，运动学资料（自行、视向速度等）是一类有效的观测判据．     

Models of CN and C2 comae for comet Tago-Sato-Kosaka and comet bennett

Based on the CN and C₂ comae isophotes for two comets (1961 IX and 1970 16) given by Rahe et al. and the relevant theory of physical chemistry, we have deduced the distributions of the CN and C₂ modecules in the coma, their scale heights and mean lifetimes. The results favour the viewpoint that HCN is the parent of CN, and that C₂H₂ is the parent of C₂.     

第一代恒星的观测和研究进展

第一代恒星（星族Ⅲ恒星）标志着宇宙从暗物质时代到现在已知的宇宙的转折点。目前对第一代恒星（星族Ⅲ恒星）的观测结果表明，在银河系中还没有发现零金属丰度的恒星，金属丰度[Fe/H]≤-2.5的恒星极少。由于近几年的BPS巡天，银河系中已知的极端贫金属丰度的恒星数目大大增多。目前，可探测到的极端贫金属星的金属丰度[Fe/H]最低约为－4．1。金属丰度在－4到－3之间的恒星大约有100多颗，这些恒星的运动学特性非常类似于其它晕星。然而还没有发现第一代恒星，或金属丰度[Fe/H]≤-5的恒星。关于第一代恒星的形成过程、初始质量函数以及存在于银河系的什么地方，都还没有任何直接的证据。但第一代恒星确实存在。第一代恒星这个谜一般的实体，向观测和理论天文学家提出了巨大挑战。为探测和预言银河系中的第一代恒星，天文学家提出了许多观测方案和理论模型。对有关第一代恒星在观测和理论研究上的进展进行了综述。     

Is Pre-Eruptive Null Point Reconnection Required for Triggering Eruptions?

We study the magnetic field evolution and topology of the active region NOAA 10486 before the 3B/X1.2 flare of October 26, 2003, using observational data from the French–Italian THEMIS telescope, the Michelson Doppler Imager (MDI) onboard Solar and Heliospheric Observatory (SOHO), the Solar Magnetic Field Telescope (SMFT) at Huairou Solar Observation Station (HSOS), and the Transition Region and Coronal Explorer (TRACE). Three dimensional (3D) extrapolation of photospheric magnetic field, assuming a potential field configuration, reveals the existence of two magnetic null points in the corona above the active region. We look at their role in the triggering of the main flare, by using the bright patches observed in TRACE 1600 Å images as tracers at the solar surface of energy release associated with magnetic reconnection at the null points. All the bright patches observed before the flare correspond to the low-altitude null point. They have no direct relationship with the X1.2 flare because the related separatrix is located far from the eruptive site. No bright patch corresponds to the high-altitude null point before the flare. We conclude that eruptions can be triggered without pre-eruptive coronal null point reconnection, and the presence of null points is not a sufficient condition for the occurrence of flares. We propose that this eruptive flare results from the loss of equilibrium due to persistent flux emergence, continuous photospheric motion and strong shear along the magnetic neutral line. The opening of the coronal field lines above the active region should be a byproduct of the large 3B/X1.2 flare rather than its trigger.     

Some geochemical patterns of shelf sediments of the China Seas

Geochemical patterns of shelf sediments of China Seas are discussed in the following order: 1) the grain-size control of elements, 2) zonal distribution of elements along the coast, 3) estuarine enrichment of elements, 4) correlation of elements, 5) philo-detrital property of elements, 6) philo-continental property of elements, 7) rapid accumulation rate of elements. Statistics show that the abundance of indicator elements in shelf sediments is relatively close to that in terrestrial rocks and continental crust, and the abundance distribution pattern of elements in shelf sediments is similar to that in continental crust.