长大隧道洞内自由测站边角交会网平面控制测量     

邹浜  刘成龙  王鹏  马洪磊  杨雪峰 《测绘科学》2014,39(10)

为了减小长大隧道洞内控制网中的横向贯通误差,文章提出一种隧道洞内平面控制测量新方法——自由测站边角交会网.文中介绍了自由测站边角交会网的网型特点、外业观测方法和内业数据处理方珐,并提出了自由测站边角交会网的附合路线闭合差和横向贯通误差计算等方法.通过对洞内横向贯通中误差进行估算并结合仿真测量实验,验证了自由测站边角交会网应用于隧道洞内平面控制中的可行性,实验表明,自由测站边角交会网在削减横向贯通误差等方面,要优于传统的导线网.  相似文献   

Evaluation of shear wave velocity profile using SPT based uphole method     

Eun-Seok Bang  Dong-Soo Kim   《Soil Dynamics and Earthquake Engineering》2007,27(8):741-758

The uphole method is a field seismic test which uses receivers on the ground surface and an underground source. A modified form of the uphole method is introduced in order to obtain efficiently the shear wave velocity (V_S) profile of a site. This method is called the standard penetration test (SPT)-uphole method because it uses the impact energy of the split spoon sampler in the SPT test as a source. Since the SPT-uphole method can be performed simultaneously with the SPT test it is economical and not labor intensive compared to the original uphole methods which use small explosives or a mechanical source. Field testing and interpretation procedures for the proposed method are described. To obtain reliable travel time information of the shear wave, the first peak point of the shear wave using two component geophones is recommended. Through a numerical study using the finite element method (FEM), the procedure of the proposed method was verified. Finally, the SPT-uphole method was performed at several sites, and the field applicability of the proposed method was verified by comparing the V_S profiles determined by the SPT-uphole method with the profiles determined by the downhole, the spectral analysis of surfaces waves (SASW) method and from the SPT-N values.  相似文献   

黄河源区生态环境恶化的现状及其原因   总被引：6，自引：0，他引：6       下载免费PDF全文

郑本兴  唐邦兴  李成治 《盐湖研究》2001,9(1):47-52

黄河是中华民族的母亲河 ,黄河流域是世界上著名的四大文明古国的发祥地之一。远古时代黄河流域气候湿润、水源丰富、土地肥沃。轩猿黄帝和他的沿黄部落就在这里开始创造中华文明。而今黄河下游常年发生断流 ,中游水土流失严重 ,河源区生态环境恶化 ,已引起我国政府和民众的关注。目前 ,防治黄河源区生态环境进一步恶化的研究工作必须加大力度 ,在财力、人力方面应给予更大的支持 ,及早编制该区治理生态环境的规划 ,加强环境保护措施  相似文献   

铜陵狮子山矿田花树坡铜矿床地质特征及矿床成因浅析   总被引：1，自引：0，他引：1  

陈帮国 《矿产与地质》2001,15(4):243-246

铜陵花树坡铜矿床生体赋存于二叠系下统栖霞组硅质层内，次要矿体赋存于孤峰组内，受层位控制，矿体围岩具有热接触变质、接触交换变质特点，受断裂构造，、岩浆岩控制明显。褶皱殂成的虚脱空间及褶皱的叠加、层间剥离等多种因纱的复合，导致了矿体的形成，成矿温度为中－高温，该矿床为层控式矽卡岩型矿床。  相似文献   

中国近海天然气水合物的研究进展   总被引：40，自引：1，他引：40  

吴必豪  张光学  祝有海  卢振权  陈邦彦 《地学前缘》2003,10(1):177-189

南海、东海具有形成天然气水合物的良好动力学环境和丰富的烃类气体来源。根据卫星对海面增温异常的观测、底水气体地球化学、标志矿物和流体组成的研究表明 ,南海、东海海底存在强烈的烃流体活动和排气作用 ;南海南北陆坡区海底气体主要由CH4组成 ,前者多为微生物成因气 ,后者多为热解气 ;冲绳海槽热液沉积区的气体 ,主要为CO2 (86 % ) ,其次为CH4、H2 、H2 S(14 % ) ,分别来自岩浆流体及陆源有机质的降解 ,也属热解成因气。地震地球物理的研究主要集中于南海东北部、北部、南部陆坡区和冲绳海槽中南部 ,测线长度还很有限 ,虽然都有BSR标志的发现 ,但质量比较好 ,研究程度也比较高的还只有南海东北部主动陆缘和北部被动陆缘的一些海域。通过沉积物烃含量和热释光的研究 ,南海、东海共获得 6个地球化学异常区。在综合对比物化探、地热等项资料的基础上初步认为 :笔架南 (Ⅰ )、台西南—东沙 (Ⅱ )异常区是寻找水合物的最佳远景区 ;琼东南—西沙海槽(Ⅲ )、中建南—中业北 (Ⅳ )和冲绳海槽南部异常区是寻找水合物和常规油气藏的有利地区 ,但Ⅳ区更有利于寻找油气 ,其余 2区更有利于寻找水合物 ;南沙海域的研究程度总体上比较低 ,但在其中的南沙海槽 ,物化探异常标志均优 ,甲烷含量较其它地区高 2个数量级  相似文献   

松辽盆地庆安地区白垩纪沉积体系和目的层地球化学特征及与铀矿化的关系   总被引：2，自引：2，他引：2  

王敢  金明  滕润球  章邦桐 《铀矿地质》2003,19(2):73-80

本在分析松辽盆地所处大地构造背景和构造演化特征的前提下，着重研究了松辽盆地庆安地区白垩系的沉积特点、沉积体系特点和泉头组目的层地球化学特征，初步论述该地区砂岩型铀矿成矿特点及与白垩纪地层的关系，并提出了该地区可能产出的铀矿床类型。  相似文献   

用改进的荧光标记技术测定具沟急游虫的摄食速率   总被引：14，自引：0，他引：14  

洪华生  柯林  黄邦钦  林学举 《海洋与湖沼》2001,32(3):260-266

于1997年10月在厦门西海域采集纤毛虫常见种－具沟急游虫，采用改进的荧光标记法的实验室条件下进行纤毛虫的摄食速度研究，结果表明，改进的荧光标记法具有操作简便，节省昂贵的荧光梁料，固定液浓度易掌握等优点，用该方法在常温下（22℃）测得纤毛虫对细菌和微藻的摄食速率分别为4.224pgC/(cell.h)和5.0pgC/(cell.h)，将此实验结果外推至自然海区，可得台湾海峡南部夏季纤毛虫对细菌，微藻的同化率分别为0.0176mgC/(m^3.d)和0.0201mgC/(m^3.d),北部冬季分别是0.0238mgC/(m^3.d)和0.0272mgC/(m^3.d).在实验条件下，温度较低时（14－26℃）对纤毛虫的摄食速度影响较大，但在较高温度（26－34℃）时差异不明显。  相似文献   

锍镍试金富集-等离子体质谱法测定煌斑岩中铂族元素   总被引：8，自引：4，他引：4  

石贵勇  孙晓明  张燕  韦慧晓  刘邦 《岩矿测试》2008,27(4):241-244

试金配料中适量加入铁粉,控制硫化铁在锍扣中的含量在20%~40%,获得的锍扣直接用水浸泡粉化后加盐酸分解,分解结束后趁热过滤,沉淀用1mL王水溶解,定容后上机测定,Cs作内标。改进后的方法空白水平进一步降低,检出限得到显著改善,分析流程简化。采用改进后的锍镍试金富集-等离子体质谱法测定了云南哀牢山金矿带煌斑岩和国家一级标准物质GBW 07288(GPt-1)、GBW 07290(GPt-3)中的铂族元素(PGEs)含量,方法检出限为0.001~0.01ng/g,精密度(RSD,n=5)为7.49%~16.6%。  相似文献   

A Bayesian hierarchical spatio-temporal model for significant wave height in the North Atlantic   总被引：1，自引：1，他引：0  

Erik Vanem  Arne Bang Huseby  Bent Natvig 《Stochastic Environmental Research and Risk Assessment (SERRA)》2012,26(5):609-632

Bad weather and rough seas continue to be a major cause for ship losses and is thus a significant contributor to the risk to maritime transportation. This stresses the importance of taking severe sea state conditions adequately into account in ship design and operation. Hence, there is a need for appropriate stochastic models describing the variability of sea states, taking into account long-term trends related to climate change. Various stochastic models of significant wave height are reported in the literature, but most are based on point measurements without considering spatial variations. As far as the authors are aware, no model of significant wave height to date exploits the flexible framework of Bayesian hierarchical space-time models. This framework allows modelling of complex dependence structures in space and time and incorporation of physical features and prior knowledge, yet at the same time remains intuitive and easily interpreted. This paper presents a Bayesian hierarchical space-time model for significant wave height. The model has been fitted by significant wave height data for an area in the North Atlantic ocean. The different components of the model will be outlined, and the results from applying the model to monthly and daily data will be discussed. Different model alternatives have been tried and long-term trends in the data have been identified for all model alternatives. Overall, these trends are in reasonable agreement and also agree fairly well with previous studies. Furthermore, a discussion of possible extensions to the model, e.g. incorporating regression terms with relevant meteorological data will be presented.  相似文献   

Performance of a nowcast/forecast system for Prince William Sound,Alaska     

Christopher N.K. Mooers  Xinglong WuInkweon Bang 《Continental Shelf Research》2009

A coastal ocean extended Prince William Sound nowcast/forecast system (EPWS/NFS) has been running semi-automatically for an extended domain of Prince William Sound (PWS), Alaska for 2 years. To determine the performance of this modeling system, an assessment is conducted. EPWS/NFS and PWS/NFS (viz., its predecessor) nowcasts are compared with observed time series of sea surface temperature (SST) and coastal sea level (CSL) at a few stations, and to velocity profiles from a moored ADCP. With the extension of the model domain to include the continental shelf outside PWS and forced by an operational global ocean model (Global-Navy Coastal Ocean Model (Global-NCOM)) and a 2D tidal model at the open boundary, EPWS/NFS has achieved significant improvement over PWS/NFS, which covered only PWS per se, for most of the predicted variables in this study. In both magnitude and phase, EPWS/NFS accurately predicts the coastal tide fluctuations, as well as M2 tidal currents in Central Sound, although significant errors in coastal tides exist during some spring and neap tide cycles. Other than for the tidal motions, EPWS/NFS generally produces less energetic CSL and velocity variations than those observed. In comparison, although PWS/NFS well predicts the coastal tides, it suffers from the absence of low-frequency CSL variations, as well as misprediction of M2 tidal currents in Central Sound. For 40 h low-passed PWS/NFS and EPWS/NFS velocities, significant phase error occurs during the model–date comparison period, while EPWS/NFS nowcasts generally produce less root-mean-square-error (rmse) and smaller correlations with the observations than PWS/NFS does. Both observations and EPWS/NFS have similar vertical profiles of baroclinic velocity standard deviations, but some substantial discrepancies occur in the velocity direction. Also, in the Central Sound, EPWS/NFS predicts well the SST seasonal cycle and a major cooling event during the summer 2005. However, for periods shorter than 1 week, both PWS/NFS and EPWS/NFS SST underestimated the observed fluctuations by an order of magnitude.  相似文献