CASS7.0的使用技巧及功能插件的制作

数字化地籍成图软件CASS7.0较以前的版本有较大改进,但在实际工作中有些操作过于繁琐,程序的实现情况与实际工作需要有一定差距。本文对CASS7.0的这些不足加以弥补,使CASS7.0更加贴近实际作业需要,使操作简便化、程序实用化。     

Trenching exposures of the surface rupture of 2008 Mw 7.9 Wenchuan earthquake,China: Implications for coseismic deformation and paleoseismology along the Central Longmen Shan thrust fault

The May 12, 2008, Mw 7.9 Wenchuan earthquake was induced by failure of two of the major faults of the Longmen Shan thrust fault zone along the eastern margin of Tibet Plateau. Our study focused on trenches across the Yingxiu–Bichuan fault, the central fault in the Longmen Shan belt that has a coseismic surface break of more than 200 km long. Trenching excavation across the 2008 earthquake rupture on three representative sites reveals the styles and amounts of the deformation and paleoseismicity along the Longmen Shan fault. Styles of coseismic deformation along the 2008 earthquake rupture at these three sites represent three models of deformation along a thrust fault. Two of the three trench exposures reveal one pre-2008 earthquake event, which is coincident with the pre-existing scarps. Based on the observation of exposed stratigraphy and structures in the trenches and the geomorphic expressions on ground surface, we interpret the 2008 earthquake as a characteristic earthquake along this fault. The interval of reoccurrence of large earthquake events on the Central Longmen Shan fault (the Yingxiu–Beichuan fault) can be inferred to be about 11,000 years according to ¹⁴C and OSL dating. The amounts of the vertical displacement and shortening across the surface rupture during the 2008 earthquake are determined to be 1.0–2.8 m and 0.15–1.32 m, respectively. The shortening rate and uplift rate are then estimated to be 0.09–0.12 mm/yr and 0.18–0.2 mm/yr, respectively. It is indicated that the deformation is absorbed mainly not by shortening, but by uplift along the rupture during the 2008 earthquake.     

地理媒介与第三空间：西方媒介与传播地理学研究进展

随着近年地理媒介逐渐兴起,城市公共空间和私人生活空间中的生产与消费过程、技术物品与符号表征之间的界限日益模糊,地理学中早先存在的“虚拟/实体”二元论亟需理论革新。作为媒介研究的“空间转向”与地理学研究的“传播转向”的产物,媒介与传播地理学的发展蕴含突破二元论的张力。论文梳理了西方媒介与传播地理学的核心概念、主要议题和研究框架,以期促进国内地理学与媒介传播学者的学术对话,扩展中国人文地理学的研究领域。西方媒介与传播地理学建立在后现代和后人类思潮影响下的动态关系性媒介与空间观之上,以纹理(texture)、移动性、物质性和具身性为核心概念。既有议题主要聚焦于数字媒介与后人类媒介空间性,数字媒介表征和算法逻辑支配下的混合空间政治,以及移动媒介带来的混合空间体验。论文借用“第三空间”概念,将其作为媒介与传播地理学超越原有二元论的潜在方向,并认为物质性和具身性构成了媒介与空间的本体论联结之处,促进国内跨学科的“媒介—空间”理论建构,为媒介城市发展与建设提供理论参考。     

基于监视相机单像量测的嫦娥三号巡视器与着陆器分离决策支持

嫦娥三号探测器系统两器分离是着陆后进行的第一个关键动作,也是后续着陆器探测和巡视器月面巡视勘察的基础,解决两器安全分离问题对于整个工程的实施具有重要意义。针对实际任务中对分离决策实时性和可靠性要求高的特点,使用基于着陆器监视相机的单像量测方法对月面环境中障碍物和通信遮挡包络进行分析计算,评估两器分离过程中的不安全因素,为两器分离决策提供支持。介绍了监视相机单像量测和通信遮挡包络计算方法,并对量测精度进行了分析验证。     

2003年云南大姚两次强震破裂区重叠程度的研究

地震破裂后,破裂区应变能是否已经充分释放.能否在破裂面内再次发生震级接近的地震,是双主震研究的重要问题.通过对2003年云南大姚两个地震序列的双差定位,发现余震区扩展,但两余震区无论在深度上还是在水平位置上基本不重叠.又通过相对定位的方法,发现7月21日主震位于10月16日主震的北西西方向.此外,还通过P波初动极性分析...     

不同观测技术的Jason-2卫星精密定轨评估

针对GPS、SLR和DORIS三种不同手段的各自定轨精度问题,本文基于不同的轨道评估方法进行了深入分析。以JASON-2卫星为例,分析了姿态模型误差及其对定轨精度的影响,分别讨论了GPS、SLR和DORIS的定轨策略和定轨精度,并基于轨道评估结果进行了轨道叠加。基于实测数据进行了试验,试验结果表明,JASON-2卫星姿态模型误差对DORIS、GPS和SLR轨道影响分别为0.040、0.036和0.033m;DORIS定轨结果优于GPS和SLR,SLR定轨精度最差;基于SLR验证和轨道重叠结果加权,对GPS、SLR和DORIS轨道进行轨道叠加,其精度一致,通过与JPL轨道比较,其径向精度为2cm。     

Seismic detections of the 15 February 2013 Chelyabinsk meteor from the dense ChinArray

Chin Array is a dense portable broadband seismic network to cover the entire continental China, and the Phase I is deployed along the north-south seismic belt in southwest China. In this study, we analyze seismic data recorded on the Chin Array following the February 15,2013 Chelyabinsk(Russia) meteor. This was the largest known object entering the Earth's atmosphere since the1908 Tunguska meteor. The seismic energy radiated from this event was recorded by seismic stations worldwide including the dense Chin Array that are more than 4000 km away. The weak signal from the meteor event was contaminated by a magnitude 5.8 Tonga earthquake occurred *20 min earlier. To test the feasibility of detecting the weak seismic signals from the meteor event, we compute vespagram and perform F-K analysis to the surface-wave data. We identify a seismic phase with back azimuth(BAZ) of 329.7° and slowness of 34.73 s/deg, corresponding to the surface wave from the Russian meteor event(BAZ *325.97°). The surface magnitude(MS) of the meteor event is 3.94 ± 0.18. We also perform similar analysis on the data from the broadband array F-net in Japan, and find the BAZ of the surface waves to be316.61°. With the different BAZs of Chin Array and F-net,we locate the Russian meteor event at 58.80°N, 58.72°E.The relatively large mislocation(*438 km as compared with 55.15°N, 61.41°E by others) may be a result of thebending propagation path of surface waves, which deviates from the great circle path. Our results suggest that the dense Chin Array and its subarrays could be used to detect weak signals at teleseismic distances.     

厚松散层下采动系数确定方法

在用传统方法求取采动系数时,往往直接笼统地利用开采深度,而对岩性差异没有做区分对待。在分析传统方法确定采动系数存在问题的基础上,探讨了开采深度中的岩性差异对采动系数的影响程度。从充分开采的临界开采宽度出发,通过理论推导,给出了考虑上覆岩层岩性时走向和倾向采动系数的计算公式,分析了松基比、上覆岩层岩性等地质采矿条件对临界开采宽度和采动系数的影响。并结合具体地表移动观测站资料,分别采用传统方法、考虑松散层岩性时和未考虑松散层岩性三种情况,求取和分析了各开采工作面达到充分采动时走向和倾向临界开采宽度以及采动系数。结果表明:本文中提出的充分采动系数计算方法与采用传统方法得到的采动系数差别较大,相对误差在3.7%~51.7%。当其他影响因素不变时,松基比越大,上覆岩层岩性越软,充分采动系数越大。在厚松散层开采条件下,评定充分采动程度时,应该考虑上覆岩层中松散层的厚度。     

Review on Climate Characteristics of Lightning Activity

Latest research results on the correlation between lightning activity and climate and climate change are reviewed. The results indicate that global lightning can be measured by using satellite optical sensor, Schumann resonances, and the time-of-arrival (TOA) techniques at very low frequency. It is observed that high lightning density areas mainly lie in seaboards, mountains, high frequency mesoscale cyclone areas, and convergent regions such as the intertropical convergence zone. Eighty-eight percent of global lightning discharges occurs in continent island and seaboard areas. The three regions hit most frequently by lightning are Congo in equatorial Africa, South America, and South and Southeast Asia. A lot of studies reveal that the global lightning activity is directly related to the earth's climate and climate change. The global lightning activity responds positively to temperature changes on many time scales, such as diurnal, pentad, intraseasonal, semiannual, annual, ENSO, and decadal time scales. However, the sensitivity of lightning to temperature changes appears to diminish at longer time scales. Since lightning can be monitored easily and continuously, it becomes a useful and important parameter for monitoring climate change. The lightning discharge is a significant producing source of nitrogen oxides (NOx) in the atmosphere, which is closely associated with ozone production and the earth's radiation balance. There exists a robust positive correlation between lightning activity and upper tropospheric water vapor on short time scales. The effect of aerosol on thunderstorm and lightning is uncertain. More observations and investigations are needed to identify the coupling mechanism between lightning and climate change.