2013年芦山M_S7.0地震的震前及临震应变异常   总被引：2，自引：0，他引：2       下载免费PDF全文

池顺良  刘琦  池毅  邓涛  廖成旺  阳光  张贵萍  陈洁 《地震学报》2013,35(3):296-303

距离芦山地震震中70 km的姑咱地震台YRY四分量钻孔应变仪2013年4月16—19日记录到8次幅度达到十倍固体潮幅的张性应变阶跃, 这在该仪器6年多运行期间尚属首次. 这些应变异常与芦山地震在时间、 空间上相关; 应变异常的主压应力方向与震前宝兴水压致裂地应力测量主压应力方向相近, 并与震前5个月中长达3个月的应变异常主压应力方向一致; 应变阶跃起始与远震震波同时到达. 综上认为, 4月16—19日的应变异常有可能是芦山地震发震断裂在破裂错动前地层蠕滑的反映.   相似文献   

国内外旋转导向钻井系统导向原理          下载免费PDF全文

雷静  杨甘生  梁涛  胡驰 《探矿工程》2012,39(9):53-58

旋转导向钻井技术是目前世界上最具代表性和先进性的钻井技术,该技术的核心是旋转自动导向系统。总结了国内外旋转导向钻井系统的发展概况,对各系统的导向机构工作原理进行了对比分析,并就旋转导向钻井系统未来的发展和完善提出了看法。  相似文献   

Knowledge, power, and tribal mapping: a critical analysis of the “return of the Truku people”     

Chun-Chieh Chi  Hsang-Te Chin 《GeoJournal》2012,77(6):733-740

Over the past decade, Indigenous peoples in Taiwan have shown a strong desire for the ??return of the Native??; this includes the Truku people in eastern Taiwan. Seizing a favorable climate of political opportunity structure in 2004, the Truku people first succeeded in obtaining the Taiwanese government??s recognition as an independent Indigenous nation??formerly considered a subgroup of the Atayal Nation. Then, riding on accumulated political resources, a few Truku elites started to engage in a government-initiated tribal mapping project. However, while tribal mapping originated in some North American Indigenous communities with a bottom-up process and spirit, the Taiwanese government sent both money (through the municipal government) and an academic expert team into the community to initiate and to assist (the elite group) with the tribal mapping project. These top-down government initiatives resulted in at least two major ill effects. First of all, two other subgroups of the Atayal Nation living in the same region were systematically excluded from the tribal mapping project, to the extent that their own traditional territories became part of the traditional territory of the newly formed Truku Nation. Secondly, possibly expecting a high political payoff on the part of elites, elite competition arose during the process of tribal mapping, with the interests of other community members largely ignored. As such, instead of establishing a decolonizing force, the ??return of the Truku?? appears to have achieved ??colonialism from within.?? This paper analyzes this process and considers ways to develop a more democratic strategy for the ??return of the Truku.??  相似文献   

2 m survey method and its improved device application in Dongshan geothermal field in Xiamen in China     

Yanjun Zhang  Yangyang Xie  Tong Zhang  Tong Liu  Chi Zhang 《Environmental Earth Sciences》2016,75(18):1290

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单站GPS接收机硬件延迟估计新算法          下载免费PDF全文

吴显兵  徐天河 《海洋测绘》2016,(1):31-34

硬件延迟的确定与所采用的电离层误差修正方法密切相关,其方法的准确度直接影响到硬件延迟的估算精度。本文综合利用广播星历所提供的Klobuchar模型系数以及双频载波与码观测量修正电离层误差,修正过程中绕开了整周模糊度的计算,给出了一种实时计算GPS接收机硬件延迟的算法,提高了实时电离层修正的精度,通过实例反算卫星硬件的延迟与广播星历中的TGD一致,验证了算法的有效性。  相似文献   

利用三维激光扫描技术监测矿区桥梁结构形变     

张驰  白志辉  李亮  陈冉丽  吴侃 《测绘通报》2022,(4):122-129

利用三维激光扫描技术测得的建筑物点云数据能够较清晰地表示建筑物的三维空间信息,提供高精度、高密度的建筑物表面描述。点云本身不直接显示自身所包含的特征信息,在进行局部形变提取时,需要进行点云分割工作。现有的应用于建(构)筑物的分割算法大多依赖于建(构)筑物特征设定突变阈值,当遇到复杂场景时,这些假设往往会导致错误。随着机器学习在点云处理领域的延伸,建(构)筑物点云数据边界的识别和分割有了新的实现思路。本文以某矿区工作面上方铁路桥两期三维激光扫描数据为例,采用神经网络方法对桥拱钢结构实行分割提取,在对1000万个标记桥梁点云数据进行训练后,神经网络模型可以学习操作人员识别点云中各点的属性并进行标记,并提取两期数据中的钢结构点云;对使用神经网络分割出的桥拱钢结构点云进行分析,通过对钢结构底边线进行特征线拟合、长度提取,计算钢结构的位移及拉伸量,并结合桥拱位移、形变量分析桥梁形变。研究表明:使用神经网络模型对标记数据进行训练可以有效识别建(构)筑物特征,并应用于建(构)筑物局部形变分析。  相似文献   

顾及气象数据的中国区域对流层延迟RBF神经网络优化模型     

徐天河  李耸  王帅民  江楠 《测绘学报》2022,51(8):1690-1707

本文基于单层气象数据(ERA5单层数据、实测气象参数)和多层气象数据(ERA5气压层数据、COSMIC掩星数据),分别采取模型法和积分法获取了我国236个陆态网GNSS测站的ZTD值,即ERA5S_ZTD、MET_ZTD、ERA5P_ZTD、RO_ZTD。以GNSS_ZTD为参考,按月评估了上述4种ZTD估计值的精度,结果表明:4种ZTD估计值的月平均RMSE依次为42.8、53.6、16.1和62.3 mm,其中基于积分法估计的ERA5P_ZTD精度最高,采用模型法计算的ERA5S_ZTD和MET_ZTD次之,而利用积分法获取的RO_ZTD值精度较低。为进一步提升利用气象数据估计ZTD值的精度,本文提出了基于RBF神经网络的对流层延迟改进模型。计算结果表明:改进模型获得的4种ZTD值与GNSS_ZTD之间的月RMSE平均值分别为23.5、32.1、14.2和40.8 mm,精度较原有ZTD估计值提升43.4%,36.3%,10.0%和34.4%。整体而言,改进模型估计ZTD值精度提升效果明显,且提升率与测站分布的密集程度有关。  相似文献   

PNT智能与智能PNT     

刘经南  罗亚荣  郭迟  高柯夫 《测绘学报》2022,51(6):811-828

定位(positioning)、导航(navigation)、授时(timing),简称PNT,是人类在长期感知、认知宇宙与人类生存的关系后,产生的与经济、社会活动密切相关的时空位置概念。PNT也是地球上的物质、能量和信息经过亿万年进化出的感知、认知与时空位置相关的智能,称为PNT智能或时空智能。而智能是生命体为适应环境生存,通过一代代继承、演进而进化出来的趋利避害行为能力的总和,可称为自然智能。本文分析了依托于生命体物质基础的自然智能特性,在此基础上探讨了生命体PNT智能的特点;概述了人类研究生命体PNT智能的最新成果、趋势和启示。其中,交互智能和PNT智能等在生命体由低级向高级的进化过程中,特别是在智人进化并形成人类文明的过程中,起到了关键性的推动作用。随着自然智能、PNT智能、人工智能研究的深入推进和交叉融合,PNT技术发展也进入智能PNT阶段。本文着重阐述了智能PNT的概念、内涵和发展趋势,从PNT应用和时空信息基础设施建设两方面,探讨了其智能化热点方向的最新进展和影响。在此基础上,也提出了一些智能PNT发展的思考和展望。  相似文献   

西施舌生长的研究   总被引：1，自引：0，他引：1  

刘德经  王家滂  肖华霖  肖思祺  黄天华  池宝兴 《广东海洋大学学报》2003,23(1):17-21

于 1998年 11月至 2 0 0 2年 12月 ,在福建长乐对西施舌 (Coelemactraantiguata)的生物学特征进行测定 ,以人工养殖方法观察其周年生长情况。观测结果表明 ,长乐沿海西施舌的群体组成以体长 6 1～ 110mm占优势 ,其频率 ( fn)为 0 .14 0～ 0 .2 2 2～ 0 .12 5。不同大小的西施舌 ,软体部肥满度指数 (CI)具有明显的季节差异。 1龄西施舌月平均体长增长 4 .0 5mm ;2龄的为 2 .31mm ;3龄的为 1.83mm ;1～ 3龄为成体生长发育阶段 ,3龄之后趋向衰老。不同发育生长阶段的壳高与壳长直线回归关系 :幼虫期H =0 .994L - 13.0 7;稚贝期H =0 .90 5L - 4.76 ;幼贝期H =0 .0 14 +0 .82 4L ;成贝期H =0 .36 7+0 .72 4L。  相似文献   

Characteristics of Seafloor Morphology and Ferromanganese Nodule Occurrence in the Korea Deep-sea Environmental Study (KODES) Area,NE Equatorial Pacific     

Hoi-Soo Jung  Young-Tak Ko  Sang-Bum Chi  Jai-Woon Moon 《Marine Georesources & Geotechnology》2013,31(3):167-180

Abstract

Seafloor morphology and ferromanganese nodule occurrence were studied using a multibeam side scan sonar (SeaBeam, 2000) and a deep-sea camera system in the Korea Deep-sea Environmental Study (KODES) area, northeast equatorial Pacific. Seafloor morphology and nodule abundance are highly variable even in this small study area. The NNE-SSW oriented hills are parallel and about 100–200 m high. Valleys are very flat-floored, while hilltops are rugged with depressions of tens of meters. Cliffs to about 100 m bound the valleys and the hills. The study area can be classified into three types based both on nodule occurrence and seafloor morphology, mostly G- and B-types and some M-type. G-type is characterized by high nodule abundance, ubiquitous bioturbation, and flat seafloor morphology, while B-type is characterized by irregular-shaped nodules, variable nodule abundance, occurrence of giant nodules and sediment lumps, rugged bottom morphology with depressions, and white calcareous surface sediments. Medium nodule abundance and a generally flat seafloor characterize M-type. G-type occurs mostly in the valley regions, while B-type is on the hilltop areas. M-type is located between the hilltop and the valley. Tectonic movement of the Pacific plate resulted in the elongated abyssal hills and cliffs. The rugged morphology on hilltops resulted from erosion and redistribution of surface siliceous sediments on hilltops by bottom currents, outcropping of underlying calcareous sediments, and dissolution of the carbonate sediments by corrosive bottom water undersaturated with CaCO₃. Sediment eroded from the hills, which is relatively young and organic-rich, is deposited in the valleys, and diagenetic metal supply to manganese nodules in the valley area is more active than on the hills. We suggest that tectonic movement ultimately constrains morphology, surface sediment facies, bottom currents and sediment redistribution, bioturbation, thickness of the sedimentary layer, and other conditions, which are all interrelated and control nodule occurrence. The best potential area for mining in the study area is the G-type valley zones with about 3–4 km width and NNW-SSE orientation.  相似文献