长三角城市群网络特征与省际边界效应——基于人口流动视角

构建城市网络化与消除行政边界所导致的阻隔效应是城市群一体化过程中所面临的双重问题.网络视角下,行政边界呈现出何种程度的空间效应是揭示区域演化机制的科学问题.基于人口流动要素构建长三角城市群网络,定量识别城市网络中的省际边界效应问题.研究指出:①网络密度、平均中心性和平均控制力三项指标一致表明基于人口流动的长三角城市群网...     

Numerical modelling on water retention and permeability of compacted GMZ bentonite under free-swelling conditions

In this study, a solid–liquid–gas coupled equation was established to simulate water retention characteristics of highly compacted GMZ bentonite. Then, modelling results were compared with laboratory test results. Results indicate that GMZ bentonite has a strong moisture expansion (or a limit drying shrinkage) characteristic. The control equation can simulate the water absorption and deformation characteristics very well at high relative humidity (or low suction). Environmental scanning electron microscope (ESEM) observation reveals the course grain soil texture of the surface under low relative humidity (RH), while the surface of GMZ bentonite becomes smooth (more fine-grained soil texture) as RH increases. Differences were found between the porosities calculated by macroexperiment results and microscopic observations with ESEM method. This is because only the interaggregate pores can be observed by ESEM photographs. Additionally, we find that the simulated effective porosities are close to the results calculated by microscopic tests, while the effective porosity is considered as the main flow channel of flow. Further, the intrinsic permeability, the effective water and gas permeability are calculated based on the proposed model. The modelling results coincide well with the laboratory experimental results and support the reliability of the proposed model.     

Responses of soil water dynamic processes and groundwater recharge to irrigation intensity and antecedent moisture in the vadose zone

In this study, a field experiment was conducted to investigate the soil water dynamics and water percolation through the deep vadose zone. A calibrated HYDRUS‐1D model was used to simulate the process of soil water movement and the water budget. Based on the measured volumetric soil water contents, the model was well calibrated and validated. Then, we conducted scenario analyses to determine the combined effects of irrigation amount (IA), antecedent soil moisture (AM), crop evapotranspiration, and deep percolation (DP) in an irrigation event. Four IAs (5, 10, 15, and 20 cm) and three AM conditions (AM‐1, AM‐2, and AM‐3) were controlled in the scenario analyses. The results indicate that according to the S_e's (effective saturation) values status and the observed or simulated depth, there could be different conclusions on the influence of DP. Under different IAs in dry (AM‐1) and medium (AM‐2) AM status, DP changed slightly; it was 0.39 and 2.47 cm in AM‐1 and 0.40 and 2.48 cm in AM‐2 for the summer maize and winter wheat crop, respectively; the AM had a crucial contribution to DP. While under the condition of wet AM (AM‐3) or small observation depth, the water inputs could have a significant effect on DP. According to increasing irrigation intensity, the higher values of S_e (>0.6) in the whole profile were only displayed between 70 and 300 cm at AM‐1, 70–500 cm at AM‐2, and 70‐below 600 cm at AM‐3, which were gradually extended and moved down with increasing AM. Hence, the IA significantly affected the water percolation at a depth of 200 cm, whereas there was a weak influence at 600 cm except in AM‐3. Furthermore, in the higher values of the S_e (>0.65) domain, the correlation between IA and DP was an exponential function and significantly under P < 0.05. In addition, DP began to occur when the soil water content was equal to or greater than 0.75 times that of the field water capacity or the S_e > 0.65. When the coarse silt layer became embedded in the silt clay soil profile, it lagged the process of water transport but did not affect permeability in the end.     

New background quasars in the vicinity of the Andromeda Galaxy discovered with the Guoshoujing Telescope (LAMOST)

Planetary nebulae (PNe) are good tracers of the stellar populations, chem-ical composition and dynamics of their host galaxies. This paper reports the dis-covery of new PNe in the outskirts of the Andromeda Galaxy (M 31) with the Guoshoujing Telescope (GSJT, formerly named the Large Sky Area Multi-Object Fiber Spectroscopic Telescope-LAMOST) during its early commissioning phase. In total, 36 candidates selected from SDSS photometry are confirmed in terms of their PN nature, including 17 new discoveries and another 19 previously known emission line objects. Their positions, spectra, radial velocities and m5007 magnitudes are presented.We discuss the potential for detecting more PNe in M 31 with GSJT's multi-object spectroscopy and the related applications in studies of the dynamics and chemistry of M31 and its assemblage history.     

城市功能区地质环境风险性分区评价方法

城市的地质环境是人类赖以生存的基础,是社会可持续发展的重要源泉。从地质环境角度出发,与城市中长期规划相对照把城市划分出不同的功能区,以此为基础建立不同功能区的城市地质环境风险性评价方法,并以四川康定城为例对此评价方法进行了验证。结果表明：此方法可行,对城市规划、政府部门的管理具有重要的意义。     

Four-dimensional variational data assimilation experiments for a heavy rain case during the 2002 IOP in China

A heavy rainfall event along the mei-yu front during 22-23 June 2002 was chosen for this study. To assess the impact of the routine and additional IOP (intensive observation period) radiosonde observations on the mesoscale heavy rainfall forecast, a series of four-dimensional variational (4DVAR) data assimilation and model simulation experiments was conducted using nonhydrostatic mesoscale model MM5 and the MM5 4DVAR system. The effects of the intensive observations in the different areas on the heavy rainfall forecast were also investigated. The results showed that improvement of the forecast skill for mesoscale heavy rainfall intensity was possible from the assimilation of the IOP radiosonde observations. However,the impact of the IOP observations on the forecast of the rainfall pattern was not significant. Initial conditions obtained through the 4DVAR experiments with a 12-h assimilation window were capable of improving the 24-h forecast. The simulated results after the assimilation showed that it would be best to perform the intensive radiosonde observations in the upstream of the rainfall area and in the moisture passageway area at the same time. Initial conditions created by the 4DVAR led to the low-level moisture convergence over the rainfall area, enhanced frontogenesis and upward motion within the mei-yu front,and intensified middle- and high-level unstable stratification in front of the mei-yu front. Consequently,the heavy rainfall forecast was improved.     

地震活动时间分布不均匀结构的多尺度检验分析

利用ldquo;非零导数显著性rdquo;检验方法, 分析了中国大陆东西部地区及青藏高原、新疆、东北、华北、华南以及台湾构造区内地震活动广义应变释放时间分布的不均匀结构. 结果表明,当广义地震应变指数eta;取较小值时,新疆、华南、东北以及台湾构造区地震活动自1970年以来总体上呈长期增强趋势, 而青藏高原与华北构造区则呈长期减弱的态势;在较小的时间窗宽情况下,各构造区均存在多尺度成丛特征,显示出地震活动在一定的尺度层次下的强弱交替现象. 但当该eta;取较大值时,除青藏高原与台湾构造区在某些尺度时间窗宽内存在某些时段趋势性变化外,其它各构造区广义地震应变释放时间分布均无统计学意义上的显著变化.      

数字指纹技术在电力系统信息保护中的应用

针对电力系统中信息数据安全问题,提出运用数字指纹技术进行数据保护,并将基于混沌序列的数字指纹技术在电力系统开发过程中加以应用．结果表明,该技术有助于电力系统中重要数 据的保护．     

全天空测云技术现状及进展

云是一种常见和重要的天气现象,在大气辐射传输中扮演着重要角色。云的形态、分布、数量及其变化标志着大气运动的状况。云的观测对军事活动、国民经济和社会服务等方面具有重要意义。目前在业务上尚未实现云的自动观测,单点测量云高的仪器已经较为成熟,然而云量和云状的自动观测仪器目前还处于研究阶段。文中总结了目前地基全天空测云仪器现状,分析了全天空云图获取、镜头保护、云点识别、云量计算、云高计算和云状识别等几个测云技术问题,最后从相关测量技术和产品应用角度做一定的思考和展望,认为需要从提高仪器性能、加强云高测量技术攻关、建立器测云分类标准等方面推进全天空测云仪器业务化应用。     

沙瓦特指数的一种迭代算法

为了提高沙瓦特指数的计算精度, 在沙瓦特指数计算方案中引入二分法:先用于计算抬升凝结高度上的要素, 进而计算假相当位温, 再依据假相当位温守恒性质用于计算500 hPa气块温度。与其他方案对比表明, 该迭代算法计算的沙瓦特指数精度较高; 与查表法所得的气块温度对比表明, 该迭代算法得到的气块温度的最大绝对误差为1.36 ℃, 平均误差 (-0.68 ℃) 与平均绝对误差 (0.69 ℃) 数值接近; 迭代算法与查表法之间以系统性偏差为主; 此外, 该迭代算法计算量小, 收敛速度快, 具有推广应用价值。