局部角度域波传播步进算法研究   总被引：2，自引：2，他引：2       下载免费PDF全文

高静怀  周艳辉  毛剑  陈文超  吴如山  李幼铭 《地球物理学报》2007,50(1):248-259

本文从非均匀介质中波动方程出发，提出了基于一般标架的相空间（局部角度域）波传播的步进算法. 该方法在构造单程波的步进算法时,在选择标架或正交基等方面有更大的自由度. 我们以不随频率及深度变化且具有变尺度特性的Gabor_Daubechies紧标架为例，给出了单程波传输算子的具体形式及相应的波场步进算法；详细讨论了基于Gabor_Daubechies标架的传输算子的高频渐近展开问题，得出了在高频、小传输步长条件下传输算子的近似解析表达式，并给出使用条件. 通过模型算例，比较了精确传输算子与高频近似传输算子用于非均匀介质中波传播的结果，说明在一定条件下由两者得出的波场几乎是相同的.  相似文献   

机载激光雷达对青岛及周边海域的气溶胶探测   总被引：11，自引：1，他引：11       下载免费PDF全文

毛敏娟  张寅超  方海涛  戚福弟  邵石生  胡欢陵  周军 《地球物理学报》2007,50(2):370-376

工作波长为532 nm的机载大气环境探测激光雷达AEDAL（Atmospheric Environment Detecting Airborne Lidar）装载在CMS_3807飞机上，于2005年11月7～11日期间在青岛地区及周边海域上空进行了飞行探测.此次实验的目的有两个：验证我国用于大气环境探测的激光雷达技术已经具备从地基向空基乃至天基发展的条件；获得青岛地区及周边海域边界层结构及大气气溶胶时空分布变化的特点.激光雷达的高时空分辨率为获取飞行路径上的边界层结构及气溶胶时空分布提供了可能.为了研究下垫面对边界层及气溶胶时空分布的影响，预定的飞行路径上包含了丰富的地形变化，有城市、丘陵、海区等.通过给出11月8日及11日的探测结果，不仅得到了不同地区边界层结构及气溶胶的时空分布特点，还可以看到冷锋、地形、地面气象场等因素对它们的影响.  相似文献   

鄂尔多斯盆地中南部三叠系延长组8油层组成岩作用及其对储层物性的控制   总被引：1，自引：0，他引：1  

姜红霞  吴亚生  罗晓容  喻建  毛明陆  杨  陈瑞银 《沉积与特提斯地质》2007,27(1):54-61

鄂尔多斯盆地中南部延长组8油层组主要成岩作用包括压实作用、石英次生加大、自生绿泥石膜生长、次生高岭石化、连晶方解石交代、长石溶蚀。根据铸体薄片,碳氧同位素分析,确定了各种主要成岩产物的空间分布和成因,分析了成岩产物分布与现今总面孔率的关系,从而确定8油层组的物性主要受石英次生加大、连晶方解石、长石溶孔、剩余原生孔隙分布的控制。石英次生加大和连晶方解石发育的地方,储层物性差;具自生绿泥石膜的剩余原生孔隙和长石溶孔发育的地方,储层物性好。  相似文献   

圆形断面管道非满流流速计算表达式   总被引：1，自引：0，他引：1       下载免费PDF全文

茅泽育  赵璇  罗昇 《水科学进展》2007,18(2):170-174

工程实际中,常需要计算某一充满度下管道非满流的流量及流速。目前大多数计算模型均采用水力半径作为反映过流断面形状及几何尺寸的特征参数。针对不同充满度的研究结果表明,这种类型模型的计算结果与真实的流动特性并不相符,尤其当水深接近管顶时。根据水动力学基本原理及试验研究手段,对圆形断面管道无压均匀流流量-充满度非单一性进行了探索,并提出了以流量作为形状特征参数的更为合理且简单实用的水流流速计算表达式。  相似文献   

阿尔金山东段拉配泉地区区域物化探异常分布规律及找矿方向     

赵更新  毛德宝张燕 《地质通报》2007,26(8):1021-1028

在分析阿尔金区域地质和物化探异常资料的基础上,对阿尔金东段的构造特点和不同地层、岩石建造的成矿元素分布分配进行了分析和讨论,重点研究了阿尔金东段区域地球化学异常的分布规律和特点,分析和推断了引起Cu、Pb、Zn、Au、Ag等异常密集区带的地质因素,讨论了地球化学异常和区域成矿问题。认为阿尔金东段成矿潜力较大,并初步探讨了找矿方向。  相似文献   

四川甘洛赤普铅锌矿床流体包裹体特征及成矿机制初步探讨   总被引：6，自引：1，他引：6  

张长青毛景文  余金杰李厚民 《岩石学报》2007,23(10):2541-2552

赤普铅锌矿床位于扬子地台西南缘川滇黔成矿区内,是川滇黔地区重要的铅锌矿床之一.通过野外和显微镜下观察,将成矿期形成的石英划分为Ⅰ、Ⅱ、Ⅲ三个阶段.本次选取了21件样品进行研究,对保存于石英、闪锌矿及硅化白云石中的原生包裹体进行的详细研究,赤普铅锌矿床中包裹体类型相对较为单一,以气液包裹体为主.Ⅰ、Ⅱ、Ⅲ阶段石英中流体包裹体均一温度和盐度范围分别为:230℃～270℃和2.74～19.68wt%(NaCl),150℃～200℃和3.71～16.99wt%(NaCI)和180℃～220℃和0.70～16.15wt%(NaCl)三个区间.主成矿阶段的闪锌矿流体包裹体的均一温度和盐度范围为127℃～210℃和4.34%～22.17%(NaCl).该矿床成矿流体均一温度和盐度范围主要在130℃～200℃和8.5%～17.0%(NaCl)之间,属于低温、中等盐度铅锌矿床.成矿流体为H2O-NaCl-CaCl2体系;成矿过程中成矿流体始终处于相对还原环境.成矿物质来源于上地壳,成矿流体主要来自围岩地层;成矿机制可能为含金属和舍还原硫流体混合成矿.该矿床应归属于密西西比型铅锌矿床.  相似文献   

隧道超前地质灾害预报综述   总被引：2，自引：0，他引：2  

毛正君  倪万魁  付晓刚 《中国地质灾害与防治学报》2007,18(4):79-81,87

隧道超前地质灾害预报在隧道施工中是十分重要的环节。文章对隧道超前地质灾害预报内容、原则、形式、方法、流程方面的研究现状进行了论述。着重对隧道超前地质灾害预报的各种方法进行了分析对比。隧道超前地质灾害预报的方法各有优缺点和局限性,应该取长补短,综合分析,根据实际情况确定应该采取的方法及其组合。在隧道超前地质灾害预报工作中,必须处理好与施工单位的关系。  相似文献   

Study of Aerodynamic Parameters on Different Underling Surfaces     

MAO Yuhao  LIU Shuhu  ZHANG Chenyi  LIU Lichao  LI Jing 《Acta Meteorologica Sinica》2007,21(1):87-97

Aerodynamic parameters including the zero-plane displacement (d), roughness length (20), and friction velocity (u*) on the different underlying surfaces of heavy-grazing site, medium-grazing site, light-grazing site, no-grazing site, dune, inter-dune, grassland, rice paddy site, wheat site, soybean site, and maize site have been computed based on the Monin-Obukhov similarity theory by utilizing the micrometeorologically observed data of dune and vegetation in the semi-arid area at Naiman, Inner Mongolia of China, conducted jointly by the Institute of Desert Research, Chinese Academy of Sciences and the National Institute of Agro-Environmental Sciences of Japan in 1990-1994. And their relationships between wind speed and Richardson number are analyzed. The aerodynamic characteristics of different man-made disturbed grassland ecosystems are also compared. Result shows that the vegetation coverage and the above-ground biomass decrease with the increase in man-made stress of the grassland. The roughness length for different underlying surfaces is closely related to vegetation height, above-ground biomass, and ground surface undulation, and Richardson number Ri is also its influencing factor. The friction velocity varies largely on different underlying surfaces, and it is positively proportional to wind speed and roughness length. The aerodynamic parameters of various times on the same underlying surface are different, too. Above results indicate that grassland and vegetation are of significance in preventing desertification, especially in the arid and semi-arid land ecosystems. And the results of this paper are also important for constructing the land surface physical process as well as regional climate model.  相似文献   

Genesis of the Changba–Lijiagou Giant Pb-Zn Deposit, West Qinling, Central China: Constraints from S-Pb-C-O isotopes     

WEI Ran  WANG Yitian  MAO Jingwen  HU Qiaoqing  QIN Siting  LIU Shengyou  YE Dejin  YUAN Qunhu  DOU Ping 《《地质学报》英文版》2020,94(4):884-900

The extensive Changba-Lijiagou Pb-Zn deposit is located in the north of the Xihe–Chengxian ore cluster in West Qinling. The ore bodies are mainly hosted in the marble, dolomitic marble and biotite-calcite-quartz schist of the Middle Devonian Anjiacha Formation, and are structurally controlled by the fault and anticline. The ore-forming process can be divided into three main stages, based on field geological features and mineral assemblages. The mineral assemblages of hydrothermal stage I are pale-yellow coarse grain, low Fe sphalerite, pyrite with pits, barite and biotite. The mineral assemblages of hydrothermal stage II are black-brown cryptocrystalline, high Fe shalerite, pyrite without pits, marcasite or arsenopyrite replace the pyrite with pits, K-feldspar. The features of hydrothermal stage III are calcite-quartz-sulfide vein cutting the laminated, banded ore body. Forty-two sulfur isotope analyses, twenty-five lead isotope analyses and nineteen carbon and oxygen isotope analyses were determined on sphalerite, pyrite, galena and calcite. The δ34 S values of stage I(20.3 to 29.0‰) are consistent with the δ34 S of sulfate(barite) in the stratum. Combined with geological feature, inclusion characteristics and EPMA data, we propose that TSR has played a key role in the formation of the sulfides in stage I. The δ34 S values of stage II sphalerite and pyrite(15.1 to 23.0‰) are between sulfides in the host rock, magmatic sulfur and the sulfate(barite) in the stratum. This result suggests that multiple S reservoirs were the sources for S2-in stage II. The δ34 S values of stage III(13.1 to 22‰) combined with the structure of the geological and mineral features suggest a magmatic hydrothermal origin of the mineralization. The lead isotope compositions of the sulfides have 206 Pb/204 Pb ranging from 17.9480 to 17.9782, 207 Pb/204 Pb ranging from 15.611 to 15.622, and 208 Pb/204 Pb ranging from 38.1368 to 38.1691 in the three ore-forming stages. The narrow and symmetric distributions of the lead isotope values reflect homogenization of granite and mantle sources before the Pb-Zn mineralization. The δ13 CPDB and δ18 OSMOW values of stage I range from-0.1 to 2.4‰ and from 18.8 to 21.7‰. The values and inclusion data indicate that the source of fluids in stage I was the dissolution of marine carbonate. The δ13 CPDB and δ18 OSMOW values of stage II range from-4 to 1‰ and from 12.3 to 20.3‰, suggesting multiple C-O reservoirs in the Changba deposit and the addition of mantle-source fluid to the system. The values in stage III are-3.1‰ and 19.7‰, respectively. We infer that the process of mineralization involved evaporitic salt and sedimentary organic-bearing units interacting through thermochemical sulfate reduction through the isotopic, mineralogy and inclusion evidences. Subsequently, the geology feature, mineral assemblages, EPMA data and isotopic values support the conclusion that the ore-forming hydrothermal fluids were mixed with magmatic hydrothermal fluids and forming the massive dark sphalerite, then yielding the calcite-quartz-sulfide vein ore type at the last stage. The genesis of this ore deposit was epigenetic rather than the previously-proposed sedimentary-exhalative(SEDEX) type.  相似文献   

INVESTIGATION OF STATUS AND DEMAND ON PUBLIC SERVICE OF EARTHQUAKE DISASTER MITIGATION IN CHINA          下载免费PDF全文

DONG Li-na  LIAN Wei-ping  CHEN Wei-tao  MA Hai-jian 《地震地质》1979,42(3):762-771

In order to make a comprehensive and systematic evaluation of the status and demands of public service of earthquake disaster mitigation, we launched an investigation with Social Opinion Polling Center of National Bureau of Statistics on the current situation of public service of earthquake disaster mitigation and the demands for it in 2018. The investigation was conducted for 18~75-year-old residents for both urban and rural areas in 31 provinces of China mainland using the Computer Assisted Telephone Interview(CATI)method and 20 078 valid samples were received in total. The questionnaire mainly includes two parts: the current situation assessment and the demand survey. The assessment of public service status consists of five indicators: earthquake emergency drill, knowledge publicity of earthquake prevention and disaster reduction, acquisition of earthquake information, reliability of information released by earthquake agencies, and overall satisfaction. The results indicate that only 27.4% of public have participated the earthquake emergency drill, and 73.5% of public have learned some knowledge about earthquake prevention and disaster reduction in different level. It shows that rural residents have a lower level of scientific knowledge of earthquake disaster mitigation although the rural residents have a higher level of satisfaction. Meanwhile, 82.9% of the public are very concerned about earthquake-related information, and the earthquake information acquisition convenience score is 81.51 points(the full score is 100 points). At present, TV is still the most popular way to obtain the earthquake-related information, besides that, network and the new media app such as Wechat and Weibo play a more and more important role. In terms of the reliability of official information published by the earthquake administration, the score is 83.69 points which indicates that the public tend to believe in official departments. Furthermore, the degree of satisfaction evaluation of public service of earthquake disaster mitigation is marked 76.44 points which shows that there is still much room for improvement. The more educated the public, the less satisfied they are with the public service of earthquake prevention and disaster reduction. The results also show that 51.81% of the public are willing to obtain earthquake warning information at their own expense. As for the demand, the most expectative services for the public are post-earthquake rescue and reconstruction, earthquake warning, and house earthquake resilience test. The results of the investigation may provide some reference for the government to provide better services of earthquake disaster mitigation and to make scientific knowledge popularization in a more scientific way.  相似文献