一种高精度数据同步测量方法研究     

李玉广  周剑  黄凤楼  张小虎 《测绘科学》2011,36(1):22-23,139

在光学摄像测量中,各种数据的同步采集在事后处理中尤为重要。目前GPS授时同步技术已经很成熟,它具有精度高,操作灵活等优点,可以很好地应用于光学摄像测量中。本文深入研究了GPS OEM板授时原理,在分析了GPS OEM板芯片中RS232时间输出与1pps输出特点的基础上,基于VC开发环境下实现了GPS OEM板与计算机串口的通信,为摄像测量设置一精确的时间起点,再利用CPU时间戳进行高精度计时,这样整个测量系统就有一高精度的时钟,任一数据的产生都被标记上精确的绝对时刻,利用这些时刻信息就间接地实现了摄像测量数据的高精度同步。实验数据表明,该方法的同步精度可以达到毫秒级,可以满足光学摄像测量的同步精度要求。  相似文献   

条形荷载下高饱和土地基的固结与沉降     

沈恺伦  王立忠 《岩土力学》2004,25(4):609-613

以Biot（1941）提出的理想土体的三维固结理论为基础,在水流连续条件中增加了考虑孔隙流体本身的压缩变形,并将这一因素以高饱和度土体的饱和度的变化为表征,写入文中建立的平面应变下的Biot二维固结方程。通过实施Laplace变换和Fourier正余弦变换获得基本方程组,求解得到初始函数表达式;再利用数值反变换得到任意时刻、任意一点的数值解,并侧重分析了高饱和土饱和度的变化对孔隙流体的压缩性能的影响,以及由此而产生的固结全过程的变化,表明了考虑孔隙流体的压缩对分析高饱和度土体的固结行为的意义。该解可以进一步推广到其它类型荷载作用在土体不同位置,以及不同边界条件下多层地基的二维固结分析。  相似文献   

Innovation-based urbanization: Evidence from 270 cities at the prefecture level or above in China   总被引：1，自引：1，他引：0  

Lyu  Lachang  Sun  Feixiang  Huang  Ru 《地理学报(英文版)》2019,29(8):1283-1299

Journal of Geographical Sciences - With the rapid development of knowledge economy, a number of important shifts are emerging in urbanization pattern across the world. Traditional urbanization...  相似文献   

Lipid biogeochemistry of Phormidium and Microcoleus mats     

Joan O. Grimalt  Rutger de Wit  Pilar Teixidor  Joan Albaigs 《Organic Geochemistry》1992,19(4-6)

A study on the predominant sources of organic matter and the main diagenetic processes in two different cyanobacterial mats from evaporite-controlled environments was performed. Fatty acids, hydrocarbons, alcohols, ketones and aldehydes were anlyzed in selected millimetre and submillimetre core sections. The changes in lipid composition were evaluated by comparison with the vertical distributions of the populations observed by optic microscopy and with the lipid patterns of enrichment cultures of species such as cyanobacteria, diatoms, purple bacteria, sulphate-reducers and methanogens obtained from the mats.The cyanobacteria Phormidium valderianum and Microcoleus chthonoplastes are the predominant primary producers, and occur almost as monocultures in the respective top layers. However, these mat-forming organisms only leave minor features in the solvent-extractable lipid sedimentary record. The predominant fatty acid distributions parallel the composition observed in the enrichment cultures of purple bacteria and appear mixed with acids characteristic of heterotrophic eubacteria such as sulphate-reducers. The concentrations of these lipids are, however, 5–10 times lower than the cyanobacterial acids from the top layer. De novo heterotrophic eubacterial synthesis is also observed in cases such as the highly branched isoprenoid eicosenes, the major hydrocarbon in the deep layers (>2 mm) of the Phormidium mat. Other major diagenetic changes involve dehydration and hydrogenation. These two processes take place concurrently under anoxic conditions and have been observed among the sterols and the isoprenoid alcohols. Significant amounts of 5ß(H)-stanols were observed in the more reducing sections where molecular indicators of methanogenic bacteria were also found.  相似文献   

Spatial and temporal distribution of phytoplankton in a highly stratified estuary (Zrmanja, Adriatic Sea)     

Zrinka Buri&#;  Ivona Cetini&#;  Damir Vili&#;i&#;  Katarina Caput Mihali&#;  Marina Cari&#;  & Goran Oluji&#; 《Marine Ecology》2007,28(S1):169-177

  相似文献   

Evaluation of various relationships of reaeration rate coefficient for modeling dissolved oxygen in a river with extreme flow variations in Pakistan     

Husnain Haider  Waris Ali  Sajjad Haydar 《水文研究》2013,27(26):3949-3963

Mathematical relationships have been developed for reaeration rate coefficient (K_a) by various researchers. These relationships have a number of variables such as depth, velocity, width, slope, Froud number, molecular diffusion coefficient, kinematic viscosity and the gas‐transfer Reynolds number. From these variables, 29 relations have been developed and divided into four groups. To evaluate their predictive capability for highly variable flow rivers receiving high pollution loads form large cities, these relationships have been used to model dissolved oxygen (DO) in the River Ravi. Such rivers are either saturated with DO during high flows or anaerobic during critical low‐flow conditions. The evaluation is based on the agreement between model DO values calculated using K_a obtained from the available equations and the measured DO concentrations in the river samples in terms of sum of square of residuals (SSR) and coefficient of determination (R²). It has been found that in general, the group of equations containing depth and velocity as the only two variables affecting K_a performed better than the equations in other groups as reflected by lower SSR and higher R² values. The study results also reveal that the turbulence‐based reaeration rate coefficient equation containing additional variables also resulted in close agreement between DO model results and the measured values. The study results identify the most important parameters affecting the reaeration rate coefficient and the suitability of various K_a relationships as well for rivers with highly variable flows. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

青岛大珠山高分异花岗岩地球化学特征与含矿性分析     

刘瑞杨  周瑶琪  周腾飞  陈彤彤  刘汉青  白冰洋  李孙义 《地质论评》2022,68(5):2022102006-2022102006

青岛大珠山位于莱州湾南西,小珠山南西侧,属于中生代晚燕山期酸性侵入花岗岩体,岩性以中粗粒钾长花岗岩和花岗斑岩为主。前人对小珠山地球化学特征已有研究,但大珠山花岗岩地球化学研究尚处空白阶段。对所取的十件样品进行岩相学、全岩主微量及稀土元素、Li同位素、锆石U- Pb测年、斜长石电子探针原位分析。结果显示：岩相学表明研究区花岗岩含有锂辉石,有明显伟晶岩脉,岩石类型为I—S型花岗岩;样品为高硅花岗岩（SiO2=66. 97%~74. 97%）;全碱含量高(Na2O+K2O=8. 70%~10. 73%),属于过铝质高钾钙碱性系列;Eu负异常明显(δEu=0. 25~0. 56)。计算高分异花岗岩常见指数：铝饱和指数(A/CNK=0. 91~1. 01);分异指数(DI)为87. 07~96. 65;锆饱和温度为836. 3~862. 6℃;锆石Ti温度计反映岩浆结晶温度为698. 5~738. 9℃。年代学表明样品年龄为113. 1±0. 36Ma,为早白垩世崂山期花岗岩。研究区花岗岩具有明显稀土元素四分组效应(TE1,3=1. 04~1. 15)和较高氧逸度,表明研究区花岗伟晶岩具有锂矿的成矿潜力。花岗岩分异过程经历斜长石、锆石、磷灰石等矿物的分离结晶。岩浆沿岛弧和大陆碰撞俯冲带裂缝上涌,形成具有成矿潜力的高分异花岗岩。  相似文献   

回注井与矿井水处理     

张路锁  孙国强  刘庆礼  孙贵生  张纯峰 《中国煤炭地质》2010,(11):48-50

为解决矿井水排放对周边环境和地下水水质的污染,对矿区水文地质资料进行了认真分析,认为梧桐庄矿井位于鼓山东南端的停滞区,属基本封闭的地垒块段,含水层基本处于停滞状态,具备回注储存高矿化度矿井水的地质构造条件。在选定区内建凿大口径回注井组,将经地面水处理厂多级处理后达标的矿井水,通过管网系统分级配送利用、回注储存,用于矿井生产、生活及农田灌溉。该工艺技术解放煤炭资源3 900万t,实现了水资源循环利用,达到了节能减排,保护生态环境的目的。  相似文献   

Generation and Evolution of Ore Fluids for Porphyry Cu-Au Mineralization of the Santo Tomas II (Philex) Deposit, Philippines   总被引：1，自引：0，他引：1  

Akira IMAI 《Resource Geology》2001,51(2):71-96

Abstract: The Santo Tomas II (Philex) deposit is a porphyry Cu‐Au deposit, located in the southern part of the Baguio mineral district, Benguet Province, northern Luzon, Philippines. The Santo Tomas II deposit is associated with an intrusive complex consisting of four rock types that are distinguished based on petrography. They are 1) post‐ore clinopyroxene‐bearing hornblende andesite porphyry, 2) ore‐generating hornblende andesite porphyry, 3) hornblende quartz diorite porphyry and 4) porphyritic hornblende quartz diorite. K‐Ar age of hydrothermal biotitization was estimated to be 1.5±0.4 Ma. A number of intrusive bodies having broadly similar petrography and K‐Ar age occur in the vicinity of the Santo Tomas II deposit, such as at Clifton, Ligay (Binang), Bumolo (Waterhole) and Philex Main Camp areas. The intrusions at the Santo Tomas II deposit and in the vicinity are characterized by high X_Mg (Mg/[Mg+Fe] atomic ratio, about 0.7 or higher) of mafic silicate phenocrysts such as hornblende, and high sulfur contents (> 0.2 wt% as SO₃) in accessory microphenocrystic apatite, suggesting a highly oxidizing condition. Sulfur is accommodated dominantly as oxidized species since the crystallization of phe‐nocrysts. Sub‐dendritic rim of tremolitic amphibole on hornblende phenocryst in the ore‐generating andesite porphyry at the Santo Tomas II deposit suggests interaction of magma and aqueous fluid(s) exsolved due to decompression during intrusion. Dissemination of magnetite is associated with hydrothermal biotitization and is followed by sheeted and stockwork quartz veinlets having silician magnetite and rare titanohematite instead of Cu‐Fe sulfides. The silician magnetite‐rich quartz veinlet was formed at f_O2 near the hematite‐magnetite buffer at nearly magmatic temperature, where sulfur dominantly existed as oxidized species such as SO₂. Chalcopyrite and bornite, which commonly exhibit micrographic texture often accompanying Pd telluride and native gold/Au‐rich electrum, are associated with subsequent anhydrite (‐quartz) veinlets and stringers. Both intermediate solid solution (iss) and bornite solid solution (bnss) are thought to have coprecipitated primarily at above 500°C based on fluid inclusion microthermometry and sulfur isotope thermometry applied for anhydrite and associated chal‐copyrite and bornite. The initial iss is considered to have converted to chalcopyrite partly replacing bnss during cooling. The hypersaline polyphase fluid inclusions abundantly found in the sheeted and stockwork quartz as well as anhydrite veinlets with scarce gaseous inclusions suggest that they have been trapped in the two aqueous fluid immiscible region. The western Luzon arc associated with porphyry Cu mineralization is characterized by oxidized hydrous magmatism and shallow emplacement, and by the source of sulfur enriched in ³⁴S.  相似文献   

Metallurgy at the Crossroads: New Analyses of Copper-based Objects at Tianshanbeilu, Eastern Xinjiang, China     

LIU Cheng  LIU Ruiliang  ZHOU Pengcheng  LU Chun  YANG Zengxin  A. Mark POLLARD  Peter HOMMEL  MA Jian  CUI Jianfeng  Peter BRAY  TONG Jianyi  Jessica RAWSON 《《地质学报》英文版》2020,94(3):594-602

Tianshanbeilu is the largest Bronze Age site in eastern Xinjiang, China. Stretching across the entire second millennium BC, it performed a prominent role in connecting the Hexi corridor, Central China and the steppe. A further insight into the metallurgical tradition and the metal supply network is of vital importance to improve our understanding of its multi-connected nature. This paper offers a new set of chemical and isotopic data on the copper-based objects at Tianshanbeilu, including alloying elements, trace elements (impurities) and lead isotopes. Combining the concentrations of arsenic and antimony reveals that arsenic was introduced to copper partially due to the use of specific minerals tethrahedrite-tennantite. Lead isotopes demonstrate that multiple sources of copper were employed at Tianshanbeilu and a majority of them are characterized by common lead, which appears rather different from those of the Central Plains and the Hexi corridor, but highly consistent with local ores. Surprisingly, one object at Tianshanbeilu contains the well-known highly radiogenic lead. This object undoubtedly marks the westernmost boundary of the distribution of the highly radiogenic lead. We also anticipate that more lead isotopic analyses in NW China will further contribute to the study of the highly radiogenic lead in Central China.  相似文献