Recent temperature increase recorded in an ice core in the source region of Yangtze River

Interests on climate change in the source region of Yangtze River have been raised since it is a region with the greatest warming over the Tibetan Plateau (TP). A 70-year history of precipitation δ~(18)O has been recovered using an ice core record retrieved in a plat portion of the firn area in the Guoqu Glacier (33°34′37.8″N, 91°10′35.3″E, 5720 m a.s.l.), Mt. Geladaindong (the source region of Yangtze River), in November, 2005. By using a significant positive relationship between ice core δ~(18)O record and summer air temperature (July to September) from the nearby meteorological stations, a history of summer air temperature has been reconstructed for the last 70 years. Summer temperature was relatively low in 1940s and high in 1950s to the middle of 1960s. The lowest temperature occurred in the middle of 1970s. Temperature was low in 1980s and dramatically increased since 1990s, keeping the trend to the begin-ning of the 21st century. The warming rate recorded in the ice core with 0.5℃/10 a since 1970s is much higher that that in the central TP and the Northern Hemisphere (NH), and it becomes 1.1℃/10 a since 1990s which is also higher than these from the central TP and the NH, reflecting an accelerated warm-ing and a more sensitive response to global warming in the high elevation region.     

Variations in the equilibrium line altitude of Urumqi Glacier No.1, Tianshan Mountains, over the past 50 years

The glacier ELA is one of the important parameters reflecting climate change.Based on observations of the equilibrium line altitude(ELA) of Urumqi Glacier No.1 in the Tianshan Mountains,we established a statistical model between ELA and its major influencing factors,warm season air temperature(air temperature averages for May,June,July and August) and annual precipitation.Result showed that,warm season air temperature was the leading climatic factor influencing ELA variations.The glacier ELA ascends(descends) 61.7 m when warm season air temperature increases(decreases) by 1°C,and ascends(descends) 13.1 m when cold season precipitation decreases(increases) by 10%.In the period 1959-2008,the glacier ELA showed a general increasing trend,ascending108 m and reaching its highest altitude in 2008 at 4168 m a.s.l.,close to the glacier summit.If future climate is similar to that in the past 50 years,the ELA of Urumqi Glacier No.1 will still ascend with a speed of 2.16 m/a.However,If future climate is similar to that in the period 2000-2008,the ELA will still ascend with a speed of 6.5 m/a before it is stable.As a result of ELA variation,the accumulation area ratio(AAR) of the glacier showed a decreasing trend during the past 50 years.     

平面广义Stewart平台位置正解求解策略及仿真

与六自由度并联机构相比,三自由度并联机构结构简单、易于控制、制造成本低,发展前景广阔。并联机构位置正解研究可为机构的设计提供必要的依据,然而到目前为止,Stewart平台位置正解的求解问题还未彻底解决。采用基于图论的自由度分析法和基于吴消元法的符号计算方法,研究了平面广义Stewart平台的位置正解求解策略。先将平面广义Stewart平台的位置正解问题转化为约束图,再对约束图进行完整约束完备化,生成构造序列,降低同时求解的方程组规模,并用吴消元法求得方程组对应的闭形解。最后对平面广义Stewart平台位置正解进行了基于MapleSim软件的仿真,用实例验证了方法的有效性。     

Distribution of <Emphasis Type="Italic">δ</Emphasis><Superscript>18</Superscript>O in surface snow along a transect from Zhongshan Station to Dome A,East Antarctica

Surface snow samples were collected during the 14th (1997/1998) and 24th (2007/2008) Chinese National Antarctica Research Expeditions along a transect from Zhongshan Station to Dome A. The stable oxygen isotope ratios of these samples were measured to investigate their relationships with temperature and geographical parameters (latitude, longitude, altitude and distance to the coast). The results reveal a strong positive correlation (R=0.945) between δ¹⁸O and mean annual temperature, with a gradient of 0.84‰°C ^–1, which is a little higher than that in Terre Adelie Land. Regression analyses also show that the δ¹⁸O of surface snow is strongly correlated with distance to the coast (R=0.942), latitude (R=0.942), and altitude (R=0.941). But no significant correlation was found between δ¹⁸O and longitude in study area. Altitude should be the most important factor influencing the δ¹⁸O distribution because of distinctive topography. The δ¹⁸O-altitude and T-altitude gradients along this transect are determined to be –1.1‰/100 m and 1.31°C/100 m, respectively.     

Recent accumulation rate at Dome A, Antarctica

Based on the horizon of β activity and the density profiles, recent accumulation rate at Dome A, Ant-arctica is calculated to be 0.023 m water equivalent per year. This value is comparative to the accumu-lation rates deduced from the other inland sites of Antarctica. Clear-sky precipitation (or diamond dust) dominates the total precipitation at Dome A region. We speculate Dome A as a potential site to discover the oldest ice in Antarctica due to its tremendous ice thickness (>3000 m), extremely low accumulation rate, and low ice velocity.     

兰州重离子加速器研究装置HIRFL

兰州重离子加速器装置HIRFL是目前我国规模最大、加速离子种类最多、能量最高的重离子研究装置,主要技术指标达到国际先进水平,是世界上几个重要的核物理研究设施之一.HIRFL由ECR离子源、扇聚焦回旋加速器SFC、分离扇回旋加速器SSC、放射性束流分离线RIBLL1和RIBLL2、冷却储存环主环CSRm和实验环CSRe等主要设施组成.HIRFL具有加速全离子的能力,可提供多种类、宽能量范围、高品质的稳定核束和放射性核束,用以开展重离子物理及交叉学科研究.本文重点介绍了兰州重离子加速器装置HIRFL的发展现状以及取得的系列成果,同时对国内外重离子加速器装置的发展现状做了简要介绍.     

First mass measurement of short-lived nuclides at HIRFL-CSR

Recent commissioning of the HIRFL-CSR has demonstrated its ability to perform direct mass measurement for short-lived nuclides. Projectile fragments produced by the 78Kr ions at 481.88 MeV/u were separated with the new radioactive beam line in Lanzhou （RIBLL2）, and injected into and stored in the experimental storage ring （CSRe）. By operating the CSRe as an isochronous mass spectrometry, a typical mass resolution around 2.0×10？5 has been achieved. The masses for 63Ge, 65As and 67Se were measured for the first time. The measured masses are compared with theoretical predictions and the location of the proton drip-line for As isotopes is discussed. The implication of the 65As mass in the astrophysical rapid proton capture process has also been addressed.     

安徽宿县朱仙庄晚侏罗世孢粉组合

这个孢粉组合是从安徽宿县朱仙庄钻孔岩心中获得的。组合特征:是裸子植物花粉占绝对优势,蕨类孢子含量很低。主要属种如下;小克拉梭粉,环圈克拉梭粉拟克拉梭克拉梭粉,网纹克拉梭粉,典型拟苏铁粉,整洁拟苏铁粉,亚颗粒拟苏铁粉,厚坦拟罗汉松粉,昆士兰拟罗汉松粉,松粉属,微细云杉粉,扁平云衫粉,有边四字粉,长方四字粉,不显四字粉,校形麻黄粉,圆形麻黄粉,无口器粉,小桫椤孢海金砂孢等。孢粉组合特征反映的地层时代属于晚侏罗世。     

Initial estimate of the contribution of cryospheric change in China to sea level rise

Recent studies have shown that cryospheric melting is becoming the dominant factor responsible for sea level rise,and that the melt-water from mountain glaciers and ice caps has comprised the majority of the cryospheric contribution since 2003.Analysis of the estimations of cryospheric melt-water and precipitation in glacier regions indicated that the potential contribution of the cryosphere in China is 0.14 to 0.16 mm a–1,of which approximately 0.12 mm a–1 is from glaciers.The contribution of glaciers in the outflow river basins is about 0.07 mm a–1,accounting for 6.4%of the total from global glaciers and ice caps.     

低温真空环境下不同密度二氧化硅气凝胶复合材料隔热性能研究

以正硅酸乙酯、乙醇等为原料,采用溶胶-凝胶反应和超临界干燥工艺制备了密度分别为30、80、120、260、320 kg/m³的纤维增强二氧化硅气凝胶复合材料,分别在常压、25 ℃下以及真空、-130~25 ℃的条件下测定了所制备的气凝胶复合材料的导热系数,研究了复合材料的密度及组成对于气凝胶材料隔热性能的影响规律。结果表明：在常压、25 ℃条件下,在不同密度的气凝胶复合材料中,密度为120 kg/m³的气凝胶复合材料的导热系数最小（0.013 W/（m·K））;密度为30、80、120 kg/m³的气凝胶复合材料的导热系数随密度增大而减小;密度为120、260、320 kg/m³的气凝胶复合材料的导热系数随密度增大而增大。在真空、-130~25 ℃的条件下,密度为120 kg/m³的气凝胶复合材料的导热系数最小;密度为30、80、120 kg/m³的气凝胶复合材料的导热系数随密度增大而减小。在130 ℃时,由于密度为320 kg/m³的气凝胶复合材料采用了抗辐射性能优异的预氧丝增强纤维,因此其导热系数最小（0.006 2 W/（m·K））。