Ablation Characteristic of Ilmenite using UV Nanosecond and Femtosecond Lasers: Implications for Non‐Matrix‐Matched Quantification          下载免费PDF全文

Zhen Li  Zhaochu Hu  Detlef Günther  Keqing Zong  Yongsheng Liu  Tao Luo  Wen Zhang  Shan Gao  Shenghong Hu 《Geostandards and Geoanalytical Research》2016,40(4):477-491

Ilmenite (FeTiO₃) is a common accessory mineral and has been used as a powerful petrogenetic indicator in many geological settings. Elemental fractionation and matrix effects in ilmenite (CRN63E‐K) and silicate glass (NIST SRM 610) were investigated using 193 nm ArF excimer nanosecond (ns) laser and 257 nm femtosecond (fs) laser ablation systems coupled to an inductively coupled plasma‐mass spectrometer. The concentration‐normalised ⁵⁷Fe and ⁴⁹Ti responses in ilmenite were higher than those in NIST SRM 610 by a factor of 1.8 using fs‐LA. Compared with the 193 nm excimer laser, smaller elemental fractionation was observed using the 257 nm fs laser. When using 193 nm excimer laser ablation, the selected range of the laser energy density had a significant effect on the elemental fractionation in ilmenite. Scanning electron microscopy images of ablation craters and the morphologies of the deposited aerosol materials showed more melting effects and an enlarged particle deposition area around the ablation site of the ns‐LA‐generated crater when compared with those using fs‐LA. The ejected material around the ns crater predominantly consisted of large droplets of resolidified molten material; however, the ejected material around the fs crater consisted of agglomerates of fine particles with ‘rough' shapes. These observations are a result of the different ablation mechanisms for ns‐ and fs‐LAs. Non‐matrix‐matched calibration was applied for the analysis of ilmenite samples using NIST SRM 610 as a reference material for both 193 nm excimer LA‐ICP‐MS and fs‐LA‐ICP‐MS. Similar analytical results for most elements in ilmenite samples were obtained using both 193 nm excimer LA‐ICP‐MS at a high laser energy density of 12.7 J cm^?2 and fs‐LA‐ICP‐MS.  相似文献   

Automated Extraction of a Five‐Year LA‐ICP‐MS Trace Element Data Set of Ten Common Glass and Carbonate Reference Materials: Long‐Term Data Quality,Optimisation and Laser Cell Homogeneity          下载免费PDF全文

David Evans  Wolfgang Müller 《Geostandards and Geoanalytical Research》2018,42(2):159-188

LA‐ICP‐MS is increasingly applied to obtain quantitative multi‐element data with minimal sample preparation, usually achieved by calibration using reference materials (RMs). However, some ubiquitous RMs, for example the NIST SRM 61× series glasses, suffer from reported value uncertainties for certain elements. Moreover, no long‐term data set of analyses conducted over a range of ablation and tuning conditions exists. Thus, there has been little rigorous examination of the extent to which offsets between measured and reported values are the result of error in these values rather than analytically induced fractionation. We present new software (‘LA‐MINE’), capable of extracting LA‐ICP‐MS data with no user input, and apply this to our system, yielding over 5 years of data (~ 5700 analyses of ten glass and carbonate RMs). We examine the relative importance of systematic analytical bias and possible error in reported values through a mass‐specific breakdown of fourteen of the most commonly determined elements. Furthermore, these data, obtained under a wide range of different ablation conditions, enable specific recommendations of how data quality may be improved, for example the role of diatomic gas, the effect of differential inter‐glass fractionation factors and choice of transport tubing material. Finally, these data demonstrate that the two‐volume Laurin ablation cell is characterised by no discernible spatial heterogeneity in measured trace element ratios.  相似文献   

Calibration of cyclic constitutive models by oscillating functions     

Muyiwa Ebenezer Alalade  Binod Kafle  Frank Wuttke  Tom Lahmer 《Geomechanics and Geoengineering》2018,13(2):146-157

Most structures are subjected to more cyclic loads during their life time than static loads. These cyclic action could be a result of either natural or man-made activities and may lead to soil failure. In order to understand the response of the foundation and its interaction with these complex cyclic loadings, various researchers have over the years developed different constitutive models. Although a lot of research is being carried out on these relatively new models, little or no details exist in literature about the model-based identification of the cyclic constitutive parameters which to a large extent govern the quality of the model output. This could be attributed to the difficulties and complexities of the inverse modeling of such complex phenomena. A variety of optimisation strategies are available for the solution of the sum of least-squares problems as usually done in the field of model calibration. However, for the back analysis (calibration) of the soil response to oscillatory load functions, this article gives insight into the model calibration challenges and also puts forward a method for the inverse modeling of cyclic loaded foundation response such that high-quality solutions are obtained with minimum computational effort.  相似文献   

Probabilistic calibration of a coupled hydro-mechanical slope stability model with integration of multiple observations     

Lulu Zhang  Fang Wu  Yafei Zheng  Lihong Chen  Jie Zhang  Xu Li 《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2018,12(3):169-182

Multiple types of responses, such as displacements, ground water level, pore water pressures, water contents, etc., are usually measured in comprehensive monitoring programmes for rainfall-induced landslide prevention. In this study, a probabilistic calibration method for coupled hydro-mechanical modelling of slope stability is presented with integration of multiple types of measurements. A numerical example of a soil slope under rainfall infiltration is illustrated to compare the effects of single and multiple types of responses on parameter estimation and model calibration. The results show that the soil parameters can be estimated with less uncertainty and total uncertainty bounds are narrower with multiple types of responses than with a single type of response. Model calibration based on multiple types of responses can compromise different responses and hence the means and standard deviations of model error are the smallest. A feasible correlation coefficient between soil modulus and permeability can be obtained from model calibration with multiple types of responses and single type of response as long as the responses include displacement data.  相似文献   

现代海底块状硫化物矿床储量估算方法探讨     

张柏松 《地质与勘探》2018,54(4):723-734

海底块状硫化物矿床具有巨大的经济价值和良好的开发前景。但是由于勘探难度和技术手段的限制,在全球已经发现的600多个海底热液喷口和硫化物矿床中,不到5%的矿床进行了详细的勘探,进行资源量计算的矿床更是屈指可数。选择适当的方法估算储量对于深海资源开发意义重大。本文系统总结了前人估算海底硫化物储量的方法,并以勘探程度相对较高、数据资料相对丰富的Atlantis-II-Deep矿床和Solwara 1矿床为例,评析了前人采用不同储量计算方法得到的结果和各种方法计算的准确性;针对有一定钻孔数据的TAG硫化物堆丘,采用距离反比法重新计算了储量,并和块段法估算的结果进行对比。得到以下结论:(1)海底硫化物矿体形态是制约储量估算方法适用性的一个重要因素;(2)传统几何法可以在极低勘探条件下估算海底硫化物储量量级;(3)对于海底硫化物储量估算,地质统计学的精度高于传统几何法;(4)较高勘探条件下距离反比法可以与地质统计学相互对照、验证;(5)在一定钻孔数量的条件下,可以应用距离反比法进行海底硫化物储量估算。  相似文献   

A geometric-based approach for road matching on multi-scale datasets using a genetic algorithm   总被引：1，自引：0，他引：1  

Alireza Chehreghan 《制图学和地理信息科学》2018,45(3):255-269

Object matching is used in various applications including conflation, data quality assessment, updating, and multi-scale analysis. The objective of matching is to identify objects referring to the same entity. This article aims to present an optimization-based linear object-matching approach in multi-scale, multi-source datasets. By taking into account geometric criteria, the proposed approach uses real coded genetic algorithm (RCGA) and sensitivity analysis to identify corresponding objects. Moreover, in this approach, any initial dependency on empirical parameters such as buffer distance, threshold of spatial similarity degree, and weights of criteria is eliminated and, instead, the optimal values for these parameters are calculated for each dataset. Volunteered geographical information (VGI) and authoritative data with different scales and sources were used to assess the efficiency of the proposed approach. According to the results, in addition to an efficient performance in various datasets, the proposed approach was able to appropriately identify the corresponding objects in these datasets by achieving higher F-Score.  相似文献   

气象卫星接收天线标校技术及应用     

张作君  王健  张小雪  吕明佳  杨蕾 《气象科技》2019,47(3):380-385

在过去的几十年中,我国气象事业的不断发展,中国风云气象卫星完成了从试验应用型向业务服务性的不断转型,因此对于卫星信号接收天线的可靠性和指向精度要求越来越高。目前用于接收风云系列极轨气象卫星下行信号的天线主要有12m和4.2m天线,其具有动态特性高、波束宽度窄等特点,因此需要在天线安装和运行期间对天线的轴系误差进行精确的标定和校准。本文在传统标校方法的基础上,提出了利用太阳进行的误差标校技术,进一步降低了标校环节的复杂程度,提高了标校精度。  相似文献   

WOFOST模型对河南省冬小麦模拟的适用性分析     

张弘  刘伟昌  李树岩 《气象与环境科学》2019,42(1):34-40

为进一步研究WOFOST模型在河南省冬麦区的适用性,以河南省30个农业气象观测站1991—2014年冬小麦观测资料、历史气象资料和土壤资料为依据,对WOFOST模型进行逐站调参和验证,分别建立了30个站的冬小麦模型参数。其中1991—2010年为模型调参年份,2011—2014年为模型验证年份。各站开花期和成熟期调参模拟的归一化均方根误差NRMSE分别小于5%和3%,验证误差分别为3.7%和2.9%。除潢川和固始外,模型对其余各站产量模拟的归一化均方根误差NRMSE全省各站均小于20.0%,验证误差全省平均为15.2%,大部分站点观测值和模拟值相关系数r通过了显著检验。利用调参后的模型模拟2011—2014年冬小麦生长动态变化可知,模拟地上部总干物重与实测单株干物重、模拟LAI与单株叶面积有较一致的变化趋势,拟合度较高。因此,WOFOST模型对河南省冬小麦主要发育阶段、产量及干物质积累模拟能力较强,具有良好的应用前景。  相似文献   

Spatial modelling of reference evapotranspiration using adjusted Blaney-Criddle equation in an arid environment     

Hossein Tabari  B. Shifteh Some'e 《水文科学杂志》2013,58(2):408-420

Abstract

The Blaney-Criddle (BC) temperature-based equation is used in areas where the complete weather data to estimate reference evapotranspiration (ET₀) by the Penman-Monteith FAO-56 (PMF-56) standard model is complex. In this study, the BC equation was first tested and calibrated against the ET₀ values computed by the PMF-56 method using data from 17 weather stations in arid regions of Iran. Then, geographical information systems (GIS)-based spatially-distributed maps of ET₀ were prepared by means of geographic/topographic factors derived from a digital elevation model (DEM) for all months, separately. The results indicate that the original BC equation overestimated PMF-56 ET₀ by 4% at the study sites. The BC equation produced closer ET₀ estimates to the PMF-56 method after it was calibrated. The error rate of <3% for the spatial modelling approach suggests that the developed ET₀ maps are reliable.

Editor D. Koutsoyiannis; Associate editor D. Yang

Citation Tabari, H., Hosseinzadeh Talaee, P., and Shifteh Some'e, B., 2013. Spatial modelling of reference evapotranspiration using adjusted Blaney-Criddle equation in an arid environment. Hydrological Sciences Journal, 58 (2), 408–420.  相似文献   

同步辐射标定平面镜反射率不确定度分析方法研究   总被引：1，自引：0，他引：1  

陈伯伦  杨正华  曹柱荣  董建军  侯立飞  崔延莉  江少恩  易荣清  李三伟  刘慎业  杨家敏 《海洋学报》2010,32(10):7078-7085

为了提高多通道软X射线能谱仪的测量精度,2009年在北京同步辐射(BSRF)软X束线源上对多种材料的掠入射平面镜的反射率进行了标定.在标定实验的基础上,对光源的单色性、高次谐波以及源强稳定性、探测器响应一致性和数据采集统计误差等多项不确定因素进行了评估,给出了反射率的修正方法和相应的不确定度分析结果.  相似文献