采样过程和模数转换对记录的影响及“真实地面运动”获取——地震学上用的数字信号处理的基本原理和实例(讲座3)     

陈祥熊  江燕 《地震地磁观测与研究》1998,(2)

通过采样过程和模数转换对记录影响的分析,讨论了数字地震仪记录的动态范围,以及如何使用谱分析方法去除仪器对最终记录的影响,以便获取“真实地面运动”的近似。  相似文献   

Analysis of Astex-Stratocumulus Observational Data Using a Mass-Flux Approach     

A. T. J. De Laat  Peter G. Duynkerke 《Boundary-Layer Meteorology》1998,86(1):63-87

A mass-flux approach is applied to observational data obtained in a convective boundary layer topped with stratocumulus clouds. The observational data were obtained from aircraft measurements during the Atlantic Stratocumulus Transition Experiment (ASTEX). A conditional sampling method is used to calculate average updraft and downdraft values. The vertical fluxes calculated with the mass-flux approach are found to be proportional to the real (measured) fluxes, with a proportionality factor being about 0.6. This value is predicted by theory for two variables having a joint Gaussian distribution function; proportionality factor = 2^-1 0.637. The horizontal fractional entrainment and detrainment rates calculated from the data ( 1–2 × 10^-2 m^-1) are an order of magnitude higher than the rates obtained by large eddy simulations for cumulus convection ( 2–3 × 10^-3 m^-1) and two orders of magnitude higher than those used in modelling cumulus convection with a mass-flux scheme in an operational weather forecast model ( 3 × 10^-4 m^-1). A numerical mass-flux model for the thermodynamics was developed and showed that results are in good agreement when compared with measured profiles of the liquid water content.  相似文献   

Efficiency verification of a horizontal flow barrier via flowmeter tests and multilevel sampling     

M. Mastrocicco  C. Sbarbati  N. Colombani  M. Petitta 《水文研究》2013,27(17):2414-2421

The remediation strategy for an industrial site located in a coastal area involves a pump and treat system and a horizontal flow barrier (HFB) penetrating the main aquifer. To validate the groundwater flow conceptual model and to verify the efficiency of the remediation systems, we carried out piezometric measurements, slug tests, pumping tests, flowmeter tests and multilevel sampling. Flowmeter tests are used to infer vertical groundwater flow directions, and base exchange index is used to infer horizontal flow directions at a metric scale. The selected wells are located both upstream and downstream of the HFB. The installation of the HFB produced constraints to the groundwater flow. A stagnant zone of contaminated freshwater floating over the salt wedge in the upper portion of the aquifer is detected downstream of the HFB. This study confirms that the adopted remediation system is efficiently working in the area upstream of the HFB and even downstream in the bottom part of the aquifer. At the same time, it has also confirmed that hot spots are still present in stagnant zones located downstream of the HFB in the upper part of the aquifer, requiring a different approach to accomplish remediation targets. The integrated approach for flow quantification used in this study allows to discriminate the direction and the magnitude of groundwater fluxes near an HFB in a coastal aquifer. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Combined use of spot samples and continuous integrated sampling in a study of storm runoff from a lowland catchment in the south of England     

A. Gkritzalis‐Papadopoulos  M. R. Palmer  M. C. Mowlem 《水文研究》2012,26(2):297-307

We have used two different sampling techniques to study the geochemical response of a small lowland rural catchment to episodic storm runoff. The first method involves traditional daily spot sampling and has been used to develop a standard end‐member mixing analysis (EMMA) of the relative contributions of ground water flow and surface runoff to the total stream flow. The second method utilizes a continuous sampling device, powered by an osmotic pump, to produce an integrated 24‐h sample of the stream flow. When combined with the EMMA results from the spot samples, analyses of the integrated samples reveal the presence of a third component that makes a significant contribution to the dissolved NO₃, Ca and K export from the catchment during the rising limb of the hydrographic profile of a storm event following a prolonged dry period. The storm occurred in the middle of the night, so that the response of the stream chemistry was not captured by the daily samples. We hypothesize that this third component is derived from the flushing of stored soil water that contains the geochemical signature of decaying vegetation. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Composite suspended sediment particles in river systems: their incidence,dynamics and physical characteristics     

J. C. Woodward  D. E. Walling 《水文研究》2007,21(26):3601-3614

Most of the existing data on the effective particle size characteristics of fluvial suspended sediment derive from instantaneous sampling methods that may not be representative of the overall suspended sediment loads. This presents difficulties when there is a need to incorporate effective particle size data into numerical models of floodplain sedimentation and sediment‐associated contaminant transfer. We have used a field‐based water elutriation apparatus (WEA) to assemble a large (36 flood) database on the time‐integrated nature of the effective and absolute particle size characteristics of suspended sediment in four subcatchments of the River Exe basin of southwest England. These catchments encompass a wide range of terrains and fluvial environments that are broadly representative of much of the UK and temperate, low relief northwest Europe. The WEA provides important data on the physical characteristics of composite particles that are not attainable using other methods. This dataset has allowed, for the first time, detailed interbasin comparisons of the time‐integrated particle size characteristics of suspended sediment and reliable estimates of the contribution of five effective size classes to the mean annual suspended sediment load of the study catchments. The suspended sediment load of each river is dominated by composite rather than primary particles, with, for example, almost 60% (by mass) of the sediment load of the River Exe at Thorverton transported as composite particles > 16 µm in size. All the effective size classes contain significant clay components. A key outcome of this study is the recognition that each catchment has a distinctive time‐integrated effective particle size signature. In addition, the time‐integrated effective particle size characteristics of the suspended loads in each of the catchments display much greater spatial variability than the equivalent absolute particle size distributions. This indicates that the processes producing composite particles vary significantly between these catchments, and this has important implications for our understanding of the dynamics of suspended sediment properties. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Water source characterization through spatiotemporal patterns of major,minor and trace element stream concentrations in a complex,mesoscale German catchment     

Holger L. Fröhlich  Lutz Breuer  Hans‐Georg Frede  Johan A. Huisman  Kellie B. Vaché 《水文研究》2008,22(12):2028-2043

The link between spatiotemporal patterns of stream water chemistry and catchment characteristics for the mesoscale Dill catchment (692 km²) in Germany is explored to assess the catchment scale controls on water quality and to characterize water sources. In order to record the spatiotemporal pattern, ‘snapshot sampling’ was applied during low, mean and high flow, including 73 nested sites throughout the catchment. Water samples were analysed for the elements Li, B, Na, Mg, Al, K, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Rb, Sr, Mo, Ba, Pb and U using inductively‐coupled‐plasma mass spectrometry, and for electric conductivity and pH. Principle component analysis and hierarchical cluster analysis were used to find typical element associations and to group water samples according to their hydrochemical fingerprints. This revealed regional hydrochemical patterns of water quality which were subsequently related to catchment attributes to draw conclusions about the controls on stream chemistry. It was found that various lithologic signals and anthropogenic point source inputs controlled the base flow hydrochemistry. During increased flows, stream waters were diluted causing additional hydrochemical variability in response to heterogeneous precipitation inputs and differences in aquifer storage capacities. The hydrochemical patterns further displayed in‐stream mixing of waters. This implied, that stream waters could be apportioned to the identified water sources throughout the catchment. The basin‐wide hydrochemical variability has the potential to outrange the tracer signatures typically inferred in studies at the hillslope scale and is able to strongly influence the complexity of the catchment output. Both have to be considered for further catchment scale tracer and modelling work. Despite the likelihood of non‐conservative behaviour, the minor and trace elements enhanced the rather qualitative discrimination of the various groundwater types, as the major cations were strongly masked by point source inputs. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

体视化关键技术   总被引：1，自引：0，他引：1  

田玲  诸昌钤  罗艳 《成都信息工程学院学报》2007,22(1):50-54

体视化技术有着广泛的应用前景。对体视化的几种关键技术进行了分类综述，介绍了体数据的表示和分类，面绘制、体绘制和混合绘制各类典型算法的原理和特点。体数据的表示方式涉及到表示精度、存储量和处理时间之间的矛盾，要根据实际问题的具体特点和要求加以选择。体数据的分类是整个可视化算法中的一个关键步骤。只有对体数据进行准确的分类，才能经过处理得出合理的图像。近年来为加快绘制速度和提高图像质量提出了许多改进的体视化算法，并对部分改进算法进行了介绍。  相似文献   

短蛸(Octopus ocellatus)酪氨酸蛋白激酶基因的克隆及其mRNA在细菌刺激后的表达规律     

张冉冉  韦秀梅  杨建敏  王卫军  刘相全  冯艳微 《海洋与湖沼》2015,46(1):173-180

从前期构建的短蛸(Octopus ocellatus)c DNA文库中克隆获得了一个短蛸酪氨酸蛋白激酶(Oo Btk)基因的c DNA全长,其c DNA全长1191 bp,包括5’非编码区(UTR)259 bp,3’UTR 227 bp,开放阅读框(ORF)705 bp,编码234个氨基酸,预测理论等电点为8.50,分子量为27.7 k Da。运用实时荧光定量PCR法分析了在健康短蛸的不同组织以及鳗弧菌和藤黄微球菌刺激后血细胞中Oo Btk的表达规律,结果表明:Oo Btk在肌肉、外套膜、鳃、鳃心、系统心脏、肝胰脏、肾囊、胃、性腺和血细胞等各检测组织中均有表达,其中在肝胰脏的表达量最高;短蛸经鳗弧菌和藤黄微球菌刺激后,Oo Btk在血细胞中的表达量呈现出了明显的被诱导表达趋势,在鳗弧菌和藤黄微球菌刺激后6 h表达即增强,并分别在鳗弧菌刺激后48 h和藤黄微球菌刺激后12 h达到最高。Oo Btk参与短蛸对于鳗弧菌和藤黄微球菌刺激的应答过程。  相似文献   

深海原位取芯钻机作业机理分析及实验研究     

杨磊  丁忠军  李德威  李宝钢  杨雷  任玉刚  刘庆亮  刘敬喜 《海洋技术学报》2015,34(1):32-37

针对深海运载器海底岩芯原位取样作业需求,对基于水下运载器的深海原位取芯钻机在深海低温、高压、底层流速多变等特点条件下的作业机理及受力进行分析,并选取硬质合金钻头和PDC钻头进行了取芯钻头的轴向力、切向力和切削功率的数学力学对比计算,确定了单环四齿周向均布的金刚石复合片(PDC)钻头设计方案。在理论分析基础上,针对深海钴结壳设计了台架试验,开展钻进试验研究。通过理论计算和实验研究,探寻了一种基于深海运载器的钴结壳小型钻机设计方法,确定了钻机功率、转速、钻进正向压力和取芯率等基本参数选取范围,对开展海底岩芯原位取样作业具有重要的指导意义。  相似文献   

页岩气资源调查评价中的采样测试工作     

李昭容  梁晓玲  王志文 《国土资源导刊(湖南)》2015,(1):90-95

页岩气是一种新的能源矿产,具有巨大的勘查开发潜力,现已成为全球油气勘探的一个新领域。采样测试作为一种勘查手段,在页岩气气藏岩性、成因来源、赋存形式、成藏特征、成藏条件、含气量等方面的研究中起着极其重要的作用,在页岩气的勘查开发中具有极其重要的意义。在页岩气资源评价等勘查中,正确采集测试样品、合理选定测试项目和测试方法、有效运用采样测试这一勘查手段,是页岩气资源调查评价中一项十分重要的工作。  相似文献