A microwave digestion technique for the extraction of fossil diatoms from coastal lake and swamp sediments     

J.F. Parr  K.H. Taffs  C.M. Lane 《Journal of Paleolimnology》2004,31(3):383-390

This study provides an introduction to a microwave digestion technique for the extraction of fossil diatoms from sediments. The microwave technique is compared with the standard diatom extraction technique of Battarbee (Diatom analysis. In: Berglund B.E. (ed.), Handbook of Holocene Palaeoecology and Palaeohydrology. John Wiley and Sons) that uses a combination of dilute hydrochloric acid and hydrogen peroxide and the advantages and disadvantages of their use are discussed. The results suggest that the microwave technique is fast, inexpensive and most importantly produces replicable fossil diatom assemblage data. Small samples sizes are used (0.3 g) for the microwave method thus lower quantities of chemicals are required (6 ml), which significantly decreases the cost of sample processing. Our results show that the microwave digestion technique is a viable alternative that will produce similar results within a shorter period of time.  相似文献   

多用途地籍信息系统的设计与研究(二)——建立多用途地籍信息系统的基本考虑     

崔卫平 《测绘学院学报》1990,(2)

本文结合北美国家多用途地籍测量的经验,讨论了规划多用途地籍信息系统中必须考虑的几个技术问题:系统用户、用户对数据和信息产品的要求、空间信息分类与编码、系统收集数据的来源与方法,供正在着手或准备建立多用途地籍信息系统的设计人员参考。  相似文献   

Characterization of Saale River Sediments by IR Spectroscopy Charakterisierung von Saale-Sedimenten durch Infrarotspektroskopie     

H. Hobert  U. Schulz  J. Einax 《洁净——土壤、空气、水》1994,22(2):76-84

The main constituents of sediment samples of the river Saale were analysed by IR spectroscopy. The composition of the sediments is determined mainly by the geological conditions (increase of carbonates, decrease of clays along the stream). Anthropogenic influences on the main components were not recognized. IR spectroscopy connected with multivariate data treatment is a suitable method to determine the main components of sediments and soils presupposed that the particle size distribution of the samples is similar. A quantitative chemical analysis in terms of individual substances or substance groups is possible if a set of reference spectra can be compiled.  相似文献   

基于供需成因分析和供需水量平衡的旱情评价方法研究   总被引：2，自引：0，他引：2  

曹升乐  王旭峰 《水文》2006,26(2):6-8

以水资源的供需差值为旱情综合评价的基础,提出了两种旱情综合评价方法,即供需成因分析评价方法和供需水量平衡评价方法,应用山东省的实际资料对评价方法进行了检验,评价结果与实际相符。  相似文献   

土坡稳定性计算极限平衡方法综述     

章熙海  杨余旺  王晓青 《华南地震》2006,26(2):28-35

介绍了土坡稳定性分析的几类方法,着重就极限平衡理论的七种方法进行评述,指出了它们的主要假设条件、计算途径以及假定条件可能存在的不合理之处,并对影响土坡稳定性的地震力计算方法也作了介绍。  相似文献   

The European VLBI Network activity in geodesy: crustal deformation in Europe     

P. Tomasi  M. J. Rioja  P. Sarti 《New Astronomy Reviews》1999,43(8-10)

The European VLBI Network has been performing a regular series of geodetic observations (EUROPE) whose main aim is to detect and monitor deformations in the European part of the Eurasian plate with high accuracy. The interaction between the African and Eurasian plates drives the tectonic motions detected in the Southern part of Europe that, with the spreading of the Middle Atlantic ridge and other local geophysical (e.g., post-glacial rebound) and geological phenomena, determine the overall crustal deformation of the region. We present the latest results obtained from the analysis of the EUROPE campaigns of observations; for certain stations, we have integrated other data acquired during different campaigns that involved at least three antennae of the network. In particular, for Ny Aalesund, we had to increase further the amount of data by using 144 experiments providing a more continuous and redundant data span to ensure a stronger statistical solution and a network with better spatial distribution. We present the velocities estimated for the antennas in the European geodetic network, along with an interpretation within their local geophysical frame.  相似文献   

江苏省农村民居抗震措施与加固方法研究   总被引：5，自引：4，他引：1  

洪海春  杨伟林  黄伟生  高志兵  宋峰 《震灾防御技术》2009,4(2):223-232

本文通过对常熟市、扬州市、姜堰市和邳州市部分村镇的农村民居抗震措施基本情况进行调查和分析,阐述了江苏省农村民居结构类型、集中住宅区建设、抗震性能的典型问题等,提出了江苏省农村民居经济、合理、有效的加固方法和改善抗震性能的具体措施。  相似文献   

漂移扫描CCD用于地球同步轨道卫星观测的初步结果   总被引：1，自引：0，他引：1  

毛银盾  唐正宏  陶隽  于涌 《天文学报》2007,48(4):475-487

对于地球同步轨道卫星,目前国内主要采用两种观测手段,即小光电望远镜短曝光观测和天文望远镜跟踪恒星(或卫星)观测.事实上,这两种手段都各自存在不足,尤其对于暗弱目标问题更加显著.利用CCD漂移扫描模式和凝视模式相结合观测地球同步轨道卫星具有明显的优势,小口径望远镜(口径约25cm)就能够获得高质量的目标和恒星圆星像与高精度的定位结果.本文重点阐述了获得高精度地球同步轨道卫星光学位置与星等的原理、方法及步骤;最后,利用实测资料的数据处理结果,分析了所获得的地球同步轨道卫星的内部精度及其误差源.  相似文献   

GRMHD/RMHD simulations & stability of magnetized spine-sheath relativistic jets     

Philip Hardee  Yosuke Mizuno  Ken-Ichi Nishikawa 《Astrophysics and Space Science》2007,311(1-3):281-286

A new general relativistic magnetohydrodynamics (GRMHD) code “RAISHIN” used to simulate jet generation by rotating and non-rotating black holes with a geometrically thin Keplarian accretion disk finds that the jet develops a spine-sheath structure in the rotating black hole case. Spine-sheath structure and strong magnetic fields significantly modify the Kelvin-Helmholtz (KH) velocity shear driven instability. The RAISHIN code has been used in its relativistic magnetohydrodynamic (RMHD) configuration to study the effects of strong magnetic fields and weakly relativistic sheath motion, c/2, on the KH instability associated with a relativistic, γ=2.5, jet spine-sheath interaction. In the simulations sound speeds up to and Alfvén wave speeds up to ∼0.56c are considered. Numerical simulation results are compared to theoretical predictions from a new normal mode analysis of the RMHD equations. Increased stability of a weakly magnetized system resulting from c/2 sheath speeds and stabilization of a strongly magnetized system resulting from c/2 sheath speeds is found.  相似文献   

Maximum Entropy Regularization Method of Ionospheric Occultation     

Zhao-Lin Liu  Xue-Jun Sun  Yang Fu  Peng Yu 《Chinese Astronomy and Astrophysics》2010

With the increasing of applications of Global Positioning System (GPS), the research on the factors affecting the radio signals is becoming more and more important. One of the most significant effects on ionosphere monitoring is the ionospheric radio occultation (IRO), and the IRO data is now serving as one of the most important monitoring sources for the ionospheric measurements. Meanwhile the inversion of the occultation data is a popular topic. The traditional Abel inversion process through compensated total electron content (TEC) is a linear inversion method, thus it would transfer the measurement errors directly to the inversion results. In order to improve the occultation results, we introduce in this paper two nonlinear methods, namely the regularization method and the maximum entropy regularization method. Through designed simulative experiments, we verify and compare these three methods, and conclude that the maximum entropy regularization method can reduce significantly the influence of measurement errors.  相似文献