Dynamic Response and Mechanical Behaviours of Geogrid for High Earth-rockfill Dams

Geotechnical and Geological Engineering - Due to the complexity of the interaction between the geogrid and the soil interface in high earth-rock dams, the method of replacing the grid with steel...     

SAGE测光巡天数据处理方法研究

元素丰度与星系演化(Stellar Abundance and Galactic Evolution,SAGE)是自主设计的能够准确计算恒星大气参数以及消光的新测光系统。对北天除银盘外共计约12 000 deg2的天区开展了SAGE系统测光巡天,计划获取约5亿颗恒星的高精度测光数据。单次曝光条件下100σ完备星等uSC～17. 3,vSAGE～16. 8(AB星等),这些为研究银河系提供宝贵的测光资料。介绍了巡天专用的数据处理程序的研究和开发,主要研究了针对单幅图像的快速自动化处理过程,重点介绍数据改正、天体测量校正、测光和流量定标过程,以及数据结果和数据质量检测等。     

Test area of the SAGE survey

Sky surveys represent one of the most important efforts to improve developments in astrophysics,especially when using new photometric bands. We are performing the Stellar Abundance and Galactic Evolution(SAGE) survey with a self-designed SAGE photometric system, which is composed of eight photometric bands. The project mainly aims to study the stellar atmospheric parameters of ～0.5 billion stars in ～12 000 deg2 of the northern sky, which mainly focuses on Galactic astronomy, as well as some aspects of extragalactic astronomy. This work introduces the detailed data reduction process of the test field NGC 6791, including the data reduction of single-exposure images and stacked multi-exposure images, and properties of the final catalog.     

Boundary-layer wind structure in a landfalling tropical cyclone

In this study, a slab boundary layer model with a constant depth is used to analyze the boundary-layer wind structure in a landfalling tropical cyclone. Asymmetry is found in both the tangential and radial components of horizontal wind in the tropical cyclone boundary layer at landfall. For a steady tropical cyclone on a straight coastline at landfall, the magnitude of the radial component is greater in the offshoreflow side and the tangential component is greater over the sea, slightly offshore, therefore the greater total wind speed occurs in the offshore-flow side over the sea. The budget analysis suggests that： （1） a greater surface friction over land produces a greater inflow and the nonlinear effect advects the maximum inflow downstream, and （2） a smaller surface friction over the sea makes the decrease of the tangential wind component less than that over land. Moreover, the boundary layer wind structures in a tropical cyclone are related to the locations of the tropical cyclone relative to the coastline due to the different surface frictions. During tropical cyclone landfall, the impact of rough terrain on the cyclone increases, so the magnitude of the radial component of wind speed increases in the offshore-flow side and the tangential component outside the radius of maximum wind speed decreases gradually.     

Waveform Characteristics of Earthquakes Induced by Hydraulic Fracturing and Mining Activities: Comparison with Those of Natural Earthquakes

Natural Resources Research - Some industrial activities, such as underground mining, hydraulic fracturing (HF), can cause microearthquakes and even damaging earthquakes. In recent years, with the...     

不同海域沉积物对尿素吸附的实验模拟研究

本文对采自渤海、黄海和东海3个典型海域的沉积物进行了尿素吸附/解吸的实验室模拟研究,用Freundlich吸附模型和Henry吸附模型分析了不同沉积物对尿素吸附的热力学特性,并研究了温度、沉积物粒径、有机质含量等因素对尿素在沉积物表面吸附的影响。结果表明,沉积物对尿素的吸附/解吸过程总体呈现3个阶段:快速吸附阶段（0~5 h）—慢速吸附阶段（5~12 h）—平衡阶段（12 h之后）。当水体中的尿素浓度较低时,沉积物解吸释放尿素,随着上覆水中尿素浓度逐渐增加,沉积物对上覆水中的尿素产生吸附行为,各海区沉积物对尿素的吸附能力由强至弱依次为渤海、东海、黄海,这可能与沉积物的类型有关。Freundlich方程和Henry方程均可模拟沉积物对尿素的吸附,温度、粒径以及沉积物中有机质含量等因素均对尿素在沉积物上的吸附产生影响,随着温度升高,尿素在沉积物上的吸附量变小,沉积物粒径越小,有机质含量越高,吸附尿素的能力越强,因此,揭示尿素在沉积物表面的环境行为时,必须考虑以上因素的影响。     

Growth and feed efficiency of juvenile shrimp Litopenaeus vannamei fed formulated diets containing different levels of poultry by-product meal

This feeding trial was conducted to evaluate the potential of poultry by-product meal (PBM) as a protein source in the culture ofLitopenaeus vannamei. Seven isonitrogenous and isoenergetic diets were formulated to near to commercial diet with about 40% protein and 7.5% lipid. Fish meal was replaced by 0, 30%, 40%, 50%, 60%, 70% and 100% of PBM (diets 1-7). The diet with 100% fish meal was used as a control (diet 1). Post-larvae were reared in an indoor semi-closed re-circulating system. Each dietary treatment was tested in 4 replicate tanks (260 L) of 40 shrimp, arranged in a completely randomized design. The shrimps were hand-fed for three times a day to near-satiation (0700, 1200 and 1800) for 60d. Percentage weight gain, survival, feed conversion ratio (FCR), protein efficiency ratio (PER) and body composition of shrimps were measured. There were no significant differences (P>0.05) in growth performance among shrimps fed diets 1-5 (0-60% fish meal replacement). However, shrimps fed diet 7 (100% fish meal replacement) had significantly lower (P<0.05) growth than those fed diets 1-5 (0-60% fish meal replacement). Shrimp fed diets 2-4 (30%-50% fish meal replacement) showed significantly higher growth than those fed diets 6 and 7 (70% and 100% fish meal replacement, respectively). Survival ranged from 94.7% to 100.0% and did not differ significantly (P>0.05) among different experimental diets. No differences in body composition were found among shrimps fed different diets. These results showed that up to 70% of fish meal protein can be replaced by PBM without adversely affecting the growth, survival, FCR, PER and body composition of Litopenaeus vannamei.     

正韵律厚油层剩余油的水平井开发技术研究

与直井相比,水平井开发具有缩短油井井距,扩大泄油面积,提高临界锥流量,更好地控制注入流体、改善波及效率等优势。在相同采液量的情况下,水平井可以降低采液强度,减缓含水上升速度。特高含水期河流相储集层的顶部是剩余油富集区,利用水平井技术挖掘正韵律厚油层顶部剩余油,取得了很好的开发效果,最终采收率较直井开发提高了14个百分点。     

丽江高美古台址和2m级望远镜项目(英文)

自 1992年起云南天文台开始了在云南省西北部的天文选址。丽江高美古最终被选择作为未来中国地基天文光学观测的新址点。并且 ,在国家科技部 ,云南省政府 ,以及中科院的支持下 ,2m级天文望远镜项目在 2 0 0 0年 12月获得立项。在文中 ,我们简要的介绍了高美古台址的情况 ,并给出了 2 .4m望远镜的详细情况 ,以及其他相关情况。     

主汛期降水量预测信号及方差权重方法的应用

为了制作四川盆地主汛期降水预报对相似方法作了改进,首先是根据四川盆地主汛期降水的前３个特征向量分别寻找有物理基础的前期信号作为预报因子,然后充分考虑各因子对总降水量贡献大小定义因子场的相似,确定相似年,最后引入“集成”的思想,由５个相似年的降水场得到预测年降水的定量客观预报。１９８１～１９９４共１４年的预报结果准确率高于当前业务预报水平。