高分辨率地震成像研究--21世纪地震学发展的一个重要趋势

随着宽频带地震观测技术的不断发展,全球及区域数字地震观测台网的密度正在不断加大,用于流动地震观测的宽频带地震仪的数量将继续迅速增加。与此同时,宽频带数字地震观测资料的积累速率按指数增长,这意味着震源波裂过程及地球内部结构的高分辨率地震成像研究将成为２１世纪地震学发展的重要趋势。地震学与地球动力学研究的关系将日趋紧密,宽频带流动地震观测的作用和重要性必将与日俱增。     

Epicenter and magnitude of large earthquake determined from high-rate GPS observations: A case study of the 2008 M8.0 Wenchuan earthquake

For earthquake and tsunami early warning and emergency response,the earthquake epicenter and magnitude should be determined rapidly and correctly.Using high-rate GPS observations,we can readily obtain precise and high resolution displacement time series and the seismic waveforms during the earthquake.In this paper,a new algorithm is proposed for estimating the earthquake epicenter and magnitude with the seismic waveforms derived from high-rate GPS data during the earthquake.A case study of the 2008 Wenchuan earthquake is conducted from 1 Hz GPS data and the epicenter and magnitude are determined.Compared with the results issued by the China Seismological Bureau,the estimation error of the epicenter and the magnitude is about 12 km and 0.1 magnitude unit,respectively.It has shown that high-rate GPS could be a new tool feasible for estimating the earthquake epicenter and magnitude,independent of or combined with seismometers.     

涡轮叶片X射线图像超分辨率重建技术

针对涡轮叶片X光无损检测系统精度低的缺点,提出一种X光DR数字图像的分辨率增强方法。该方法采用一组包含相对位移的叶片X光图像,通过一种频率域方法对它们进行亚像素精确配准,然后采用非均匀插值重建出一幅高分辨率图像。实验结果表明该方法具有提高涡轮叶片X光数字图像分辨率的能力,具有良好的应用价值。     

Has climate change driven spatio-temporal changes of cropland in northern China since the 1970s?

Improving the understanding of cropland change and its driving factors is a current focus for policy decision-makers in China. The datasets of cropland and cropland changes from the 1970s to the 2000s were used to explore whether climate change has produced spatio-temporal changes to cropland in northern China since the 1970s. Two representative indicators of heat and water resources, which are important determinants of crop growth and productivity, were considered to track climate change, including active accumulated temperatures ≥10 °C (AAT10) and the standardized precipitation evapotranspiration index (SPEI). Our results showed that rapid cropland change has occurred in northern China since the 1970s, and the area of cropland reclamation (10.23 million ha) was much greater than that of abandoned cropland (2.94 million ha). In the 2000s, the area of cropland with AAT10 higher than 3,000 °C·d increased, while the area of cropland with an SPEI greater than 0.25 decreased compared to the 1970s, 1980s and 1990s. It appears that climate warming has provided thermal conditions that have aided rapid cropland reclamation in northern China since the 1970s, and drier climatic conditions did not become a limiting factor for cropland reclamation, especially from the 1990s to the 2000s. Approximately 70 % of cropland reclamation areas were located in warmer but drier regions from the 1990s to the 2000s, and approximately 40 % of cropland abandonment occurred in warmer and wetter conditions that were suitable for agriculture during the periods from the 1970s to the 1980s and the 1990s to the 2000s. Our results suggest that climate change can be considered a driving factor of cropland change in the past several decades in northern China, in addition to socioeconomic factors.     

The pattern,evolution, and mechanism of venture capital flows in the Guangdong-Hong Kong-Macao Greater Bay Area,China

As an important innovation flow, venture capital has been examined in urban network research. However, the segmentation of capital categories and the cross-scale connection of capital remain scarcely analyzed. This study focuses on the structure and industry differentiation of venture capital flows in the Guangdong-Hong Kong-Macao Greater Bay Area(GBA) and its cross-scale network characteristics. Based on a venture capital database covering capital amount, investment subject address information,...     

内蒙古和林格尔新区核心区地下空间适宜性评价

本文以内蒙古和林格尔新区核心区为研究范围,利用已有调查数据,基于MapGIS平台,从水文地质、工程地质、不良地质及地貌4个方面选取9个因子组成了地下空间适宜性评价指标体系,采用层次分析法对研究区地下空间适宜性进行了评价。评价结果显示：研究区浅层地下空间较适宜区占总面积99.71%;中层地下空间较适宜区占总面积95.03%;深层地下空间较适宜区分布于研究区东南部,占总面积26.95%,次适宜区大面积分布于研究区中西部区域,占总面积72.27%。研究结果表明：研究区地下空间资源综合适宜性等级基本以较适宜、次适宜为主,区内不同竖向层次与不同区位地下空间资源的适宜性存在差异,资源条件总体上呈现\     

Compression behavior of MICP-treated sand with various gradations

Acta Geotechnica - One-dimensional compression tests on quartz sands treated by microbially induced carbonate precipitation (MICP) were carried out to evaluate the effects of gradation and calcium...     

流动注射-光度法测定地质样品中痕量碘

利用I~-对4,4′-四甲基二氨基二苯甲烷(4,4′-TMB-DPM)与氯胺T反应的催化作用,建立了流动注射-分光光度测定地质样品中痕量碘的方法。采用不等流速合并带法,分析速度快、节省试剂、灵敏度高。与高温水解法释放I~-相结合,使样品处理简单、干扰离子少。对于含I~-10μg/L的水样,其RSD(n=19)为1.1％,检出限为0.3ng/ml。用于水系沉积物、土壤分析时,含碘1.6×10~(-6)的样品RSD(n=10)为6.1％,检出限为0.08×10~(-6)。测量速度50N/h。