Spectroscopic study of globular clusters in the halo of M31 with the Xinglong 2.16 m telescope

We present spectroscopic observations for 11 confirmed globular clusters(GCs) of M31 with the OMR spectrograph on the 2.16 m telescope at the Xinglong site of National Astronomical Observatories,Chinese Academy of Sciences.Nine of our sample clusters are located in the halo of M31 and the most remote one is out to a projected radius of 78.75 kpc from the galactic center.For all our sample clusters,we measured the Lick absorption-line indices and radial velocities.It is noted that most GCs in our sample are ...     

Possible distance indicators in gamma-ray pulsars

Distance measurement of gamma-ray pulsars is a current challenge in pulsar studies.The Large Area Telescope(LAT) aboard the Fermi gamma-ray observatory discovered more than 70 gamma-ray pulsars including 24 new gamma-selected pulsars with almost no distance information.We study the relation between gammaray emission efficiency(η=Lγ/E˙) and pulsar parameters for young radio-selected gamma-ray pulsars with known distance information in the first gamma-ray pulsar catalog reported by Fermi/LAT.We have introduce...     

A laboratory study of rheological properties of mudflows in Hangzhou Bay,China

A laboratory study of the rheology of mudflows in Hangzhou Bay, China, is reported in this paper. Both the steady and oscillatory （dynamic） rheological properties are studied using RMS-605 rheometer. A Dual-Bingham model is proposed for analyzing flow curves and compared with Worrall-Tuliani model. It is found that Dual-Bingham plastic rheological model is easier to implement than Worrall-Tuliani model and can provide satisfactory representations of the steady mudflows in Hangzhou Bay and other published data. The dependence of the yield stress and viscosity on sediment concentration is discussed based on the data from Hangzhou Bay mud and other published data. For the dynamic rheologieal properties of Hangzhou Bay mud, empirical expressions for elastic modulus and dynamic viscosity are provided in the form of exponential functions of sediment volume concentration, and comparisons with other published data also discussed.     

广西十万大山盆地中生代地层的裂变径迹研究及其地质意义

对采自中国南方十万大山盆地中生代地层的11个磷灰石样品和6个锆石样品进行了裂变径迹分析,所有磷灰石样品以及锆石样品SS-5、SW033、SW055的裂变径迹年龄数据均小于样品的地层年龄,表明这些样品在沉积后所经历的埋藏温度曾经大于最大退火温度。样品Shw-1、SW027、SW025的锆石裂变径迹年龄大于样品的地层年龄,反映的是源区的锆石年龄。根据磷灰石裂变径迹年龄数据进行的时间一温度历史模拟表明,十万大山地区的磷灰石样品基本反映了相同的低温段热演化史。各个样品在41～85Ma之间分别达到最大古地温值(介于98～175℃之间),此后各个样品的热演化史总体上呈冷却的趋势。自晚白垩世以来,盆地各地普遍遭受了抬升剥蚀过程,估算的地层剥蚀量在2281～4484m之间。     

南亚高压季节性变化与甘肃省春季和初夏降水关系初探

通过对南亚高压的季节性变化与甘肃省春季第一场≥10mm的区域性降水即第一场透雨出现时间和初夏转入多雨期的统计分析,初步揭示了南亚高压在季节性变化过程中及最终在青藏高原上空建立与甘肃省特别是甘肃河东地区春季第一场透雨及转入多雨期的相关关系。分析结果表明,南亚高压在季节性变化过程中登上中南半岛与甘肃省河东地区春季第一场透雨的出现具有显著关系,南亚高压在青藏高原上空建立与甘肃省初夏转入多雨期同样具有显著关系。因此。准确掌握南亚高压的季节性变化及登上高原的日期。不论对于准确预报出春季第一场透雨,还是转入多雨期,都有着重要的参考和指导意义。     

Interannual variability of latent and sensible heat fluxes in the South China Sea

The South China Sea (SCS) is significantly influenced by El Nio and the Southern Oscillation (ENSO) through ENSO-driven atmospheric and oceanic changes.We analyzed measurements made from 1960 to 2004 to investigate the interannual variability of the latent and sensible heat fluxes over the SCS.Both the interannual variations of latent and sensible heat fluxes are closely related to ENSO events.The low-pass mean heat flux anomalies vary in a coherent manner with the low-pass mean Southern Oscillation Index ...     

SIMS Pb/Pb dating of Zr-rich minerals in lunar meteorites Miller Range 05035 and LaPaz Icefield 02224:Implications for the petrogenesis of mare basalt

Miller Range (MIL) 05035 and LaPaz Icefield (LAP) 02224 are unbrecciated lunar basalt meteorites. In this report, we studied their petrography and mineralogy and made in situ uranogenic Pb/Pb dating of Zr-rich minerals. Petrography and mineralogy of these two lunar meteorites are consistent with previous investigations. The zirconolite Pb/Pb age of MIL 05035 is 3851±8 Ma (2σ), in excellent agreement with previous reports. This age suggests that MIL 05035 could be paired with Asuka 881757, a low-Ti mare basalt meteorite. The magmatic event related to MIL 05035 was probably due to the late heavy impact bom- bardment on the moon around 3.9 Ga. One baddeleyite grain in LAP 02224 shows a large variation of Pb/Pb age, from 3109±29 to 3547±21 Ma (2σ), much older than the whole-rock age of the same meteorite (~3.02±0.03 Ga). The other baddeleyite grain in LAP 02224 has an age of 3005±17 Ma (2σ). The result indicates that the minimum crystallization age of LAP 02224 is ~3.55 Ga and the younger ages could reflect late thermal disturbance on U-Pb system.     

Accuracy assessments and uncertainty analysis of spatially explicit modeling for land use/cover change and urbanization:A case in Beijing metropolitan area

Spatially explicit modeling plays a vital role in land use/cover change and urbanization research as well as resources management;however,current models lack proper validation and fail to incorporate uncertainty into the formulation of model predictions.Consequently,policy makers and the general public may develop opinions based on potentially misleading research,which fails to allow for truly informed decisions.Here we use an uncertainty strategy of spatially explicit modeling combined with the series stat...     

地球内部水与无机成烃

地球内部水是广泛存在的,由于高温高压作用使其具有独特的物理和化学性质,它对于烃类物质生成和运移都具有重要的意义。在地球内部,水与无机矿物作用产生H2或者O2,对C-O-H流体平衡存在影响,这是烃类物质形成和稳定的重要因素。地球内部高温高压水热流体一方面为有机反应提供高效的介质,另一方面它直接作为反应物与碳酸盐和金属碳化物反应生成烃类物质。对于地球早期有机物形成和水热条件下有机物的主要合成反应——费托反应,其重要的成烃物质H2主要由水与矿物作用产生,这是目前较为认同的地球内部无机成烃的重要方式。