ZAF, PAP, Φ(ρz), α-FACTOR..: A Comparison of the Relative Accuracies of The Alphabet Soup of Correction Factors for “Non-Optimized” Samples

1996 ◽  
Vol 54 ◽  
pp. 470-471
Author(s):  
John T. Armstrong
Keyword(s):  
Bulk Material ◽  
Analytical Data ◽  
Sample Surface ◽  
Beam Current ◽  
Correction Factors ◽  
Correction Procedure ◽  
Data Set ◽  
Quantitative Analyses ◽  
Relative Errors ◽  
Very High

The ultimate practical test of the utility of a correction procedure for quantitative x-ray microanalysis is how well the analyses of standards of interest conform to their known compositions. Many papers have been published testing various correction algorithms by processing data from sets of quantitative analyses through the corrections and then comparing the resulting error histograms {e.g., Fig. 1). The best correction procedure is usually considered to be the method that results in error histograms with the minimum mean relative error and the smallest standard deviation for the distribution of relative errors. Such evaluations can be misleading for a number of reasons: (1) the correction procedure may have been “adjusted” by adding empirical factors to produce superior results for a particular type of specimen. If the test data either include these data or include samples of similar composition to those employed for the refinement, the results may appear artificially good and may not work nearly as well for other types of specimens. (2) The analytical data used for testing may itself be flawed, either because the samples were not actually the compositions they were thought to be (or the sample surface analyzed was not the same composition as that published for the bulk material); or because the surface or the sample was contaminated, rough or charging; or because the analytical conditions were not well controlled. (Many of the published k-factors used in evaluating correction procedures [e.g., ref. 1] were obtained in the early days of microbeam analysis, using instruments having poor control over high voltage and beam current stability with low spectrometer take-off angles.) (3) The analytical data may contain specimens analyzed under unusual conditions {e.g,, very high or veiy low accelerating potentials) that may have very large corrections dominating the data set that may never be encountered in normal analysis.

scholarly journals Elemental ratio measurements of organic compounds using aerosol mass spectrometry: characterization, improved calibration, and implications

2015 ◽  
Vol 15 (1) ◽  
pp. 253-272 ◽  
Author(s):  
M. R. Canagaratna ◽  
J. L. Jimenez ◽  
J. H. Kroll ◽  
Q. Chen ◽  
S. H. Kessler ◽  
...  
Keyword(s):  
High Resolution ◽  
Vacuum Ultraviolet ◽  
Laboratory Data ◽  
Detailed Examination ◽  
Relative Difference ◽  
Data Set ◽  
Elemental Ratios ◽  
Standard Data ◽  
Aerosol Mass ◽  
Relative Errors

Abstract. Elemental compositions of organic aerosol (OA) particles provide useful constraints on OA sources, chemical evolution, and effects. The Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) is widely used to measure OA elemental composition. This study evaluates AMS measurements of atomic oxygen-to-carbon (O : C), hydrogen-to-carbon (H : C), and organic mass-to-organic carbon (OM : OC) ratios, and of carbon oxidation state (OS C) for a vastly expanded laboratory data set of multifunctional oxidized OA standards. For the expanded standard data set, the method introduced by Aiken et al. (2008), which uses experimentally measured ion intensities at all ions to determine elemental ratios (referred to here as "Aiken-Explicit"), reproduces known O : C and H : C ratio values within 20% (average absolute value of relative errors) and 12%, respectively. The more commonly used method, which uses empirically estimated H2O+ and CO+ ion intensities to avoid gas phase air interferences at these ions (referred to here as "Aiken-Ambient"), reproduces O : C and H : C of multifunctional oxidized species within 28 and 14% of known values. The values from the latter method are systematically biased low, however, with larger biases observed for alcohols and simple diacids. A detailed examination of the H2O+, CO+, and CO2+ fragments in the high-resolution mass spectra of the standard compounds indicates that the Aiken-Ambient method underestimates the CO+ and especially H2O+ produced from many oxidized species. Combined AMS–vacuum ultraviolet (VUV) ionization measurements indicate that these ions are produced by dehydration and decarboxylation on the AMS vaporizer (usually operated at 600 °C). Thermal decomposition is observed to be efficient at vaporizer temperatures down to 200 °C. These results are used together to develop an "Improved-Ambient" elemental analysis method for AMS spectra measured in air. The Improved-Ambient method uses specific ion fragments as markers to correct for molecular functionality-dependent systematic biases and reproduces known O : C (H : C) ratios of individual oxidized standards within 28% (13%) of the known molecular values. The error in Improved-Ambient O : C (H : C) values is smaller for theoretical standard mixtures of the oxidized organic standards, which are more representative of the complex mix of species present in ambient OA. For ambient OA, the Improved-Ambient method produces O : C (H : C) values that are 27% (11%) larger than previously published Aiken-Ambient values; a corresponding increase of 9% is observed for OM : OC values. These results imply that ambient OA has a higher relative oxygen content than previously estimated. The OS C values calculated for ambient OA by the two methods agree well, however (average relative difference of 0.06 OS C units). This indicates that OS C is a more robust metric of oxidation than O : C, likely since OS C is not affected by hydration or dehydration, either in the atmosphere or during analysis.

Mechanical and optical behaviors: strain synergy effects in high temperature phase oxide of lead

2021 ◽  
Author(s):  
Qidong Kang ◽  
Fei Yang ◽  
Xinyu Zhang ◽  
Ziyu Hu
Keyword(s):  
High Temperature ◽  
Absorption Coefficient ◽  
Bulk Material ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
Synergy Effects ◽  
High Absorption Coefficient ◽  
Very High ◽  
High Absorption

Since lead has a very high absorption coefficient μ, that the radiations from within the bulk material do not penetrate the layers. While, the oxygen and water (O2 and H2O)...

Alloy surface composition resulting from fabrication, as determined by s.i.m.s. (secondary ion mass spectrometry)

1980 ◽  
Vol 295 (1413) ◽  
pp. 134-135
Keyword(s):  
Secondary Ion Mass Spectrometry ◽  
Surface Composition ◽  
Ion Beam ◽  
Sample Surface ◽  
Beam Current ◽  
Ion Source ◽  
Beam Current Density ◽  
Dynamic Mode ◽  
Static Mode ◽  
Subsequent Performance

In s.i.m.s. the sample surface is ion bombarded and the emitted secondary ions are mass analysed. When used in the static mode with very low primary ion beam current densities (10 -11 A/mm 2 ), the technique analyses the outermost atomic layers with the following advantages (Benninghoven 1973, I975): the structural—chemical nature of the surface may be deduced from the masses of the ejected ionized clusters of atoms; detection of hydrogen and its compounds is possible; sensitivity is extremely high (10 -6 monolayer) for a number of elements. Composition profiles are obtained by increasing the primary beam current density (dynamic mode) or by combining the technique in the static mode with ion beam machining with a separate, more powerful ion source. The application of static s.i.m.s. in metallurgy has been explored by analysing a variety of alloy surfaces after fabrication procedures in relation to surface quality and subsequent performance. In a copper—silver eutectic alloy braze it was found that the composition of the solid surface depended markedly on its pretreatment. Generally there was a surface enrichment of copper relative to silver in melting processes while sawing and polishing enriched the surface in silver

scholarly journals Re-evaluation of the 1950–1962 total ozone record from Longyearbyen, Svalbard

2006 ◽  
Vol 6 (3) ◽  
pp. 3913-3943 ◽  
Author(s):  
C. Vogler ◽  
S. Brönnimann ◽  
G. Hansen
Keyword(s):  
Total Ozone ◽  
Systematic Bias ◽  
Correction Factors ◽  
Polar Night ◽  
Data Set ◽  
Wide Range ◽  
Wavelength Pair ◽  
Original Measurement ◽  
Normalization Function ◽  
Dobson Spectrophotometer

Abstract. The historical total ozone measurements taken with Dobson Spectrophotometer #8 at Longyearbyen, Svalbard, Norway, in the period 1950–1962 have been re-analyzed and homogenized based on the original measurement logs, using updated relevant parameters. In lack of sufficient calibration information, an empirical quality assessment was performed, based on a climatological comparison with ozone measurements in Tromsø, using TOMS data at both sites in the period 1979–2001, and Dobson data in the period 1950–1962. The assessment revealed that, as in the case of the Tromsø measurements, the C wavelength pair direct-sun measurements are most trustworthy (and most frequent), while the WMO standard reference mode AD direct-sun has a systematic bias relative to this data set. Zenith-blue (ZB) measurements at solar zenith angles (SZA) <80° were homogenized using two different polynomials before and from 1957; also ZB measurements at larger SZAs were homogenized by means of a normalization function derived from days with measurements over a wide range of SZAs. CC' zenith-cloudy measurements, which are particularly frequent during the summer months, were homogenized by applying correction factors for only two different cloud types: high thin clouds and medium/low/thick clouds; a further diversification of corrections reflecting cloud conditions did not prove significant. The combination of all measurements yields a total of 4837 single values, covering 1676 days from September 1950 to September 1962; moon measurements during the polar night add another 137 daily means. The re-evaluated data show a convincing agreement with measurements since 1979 (TOMS, SAOZ, Dobson) as well as with the 1957–1962 data stored at the World Ozone and UV Data Centre (WOUDC).

scholarly journals Modelling head loss along emitting pipes using dimensional analysis

2015 ◽  
Vol 35 (3) ◽  
pp. 442-457 ◽  
Author(s):  
Acácio Perboni ◽  
Jose A. Frizzone ◽  
Antonio P. de Camargo ◽  
Marinaldo F. Pinto
Keyword(s):  
Dimensional Analysis ◽  
Excellent Result ◽  
Head Loss ◽  
Maximum Deviation ◽  
Maximum Relative Error ◽  
Data Set ◽  
Head Losses ◽  
Model Based ◽  
Precision And Accuracy ◽  
Relative Errors

Local head losses must be considered in estimating properly the maximum length of drip irrigation laterals. The aim of this work was to develop a model based on dimensional analysis for calculating head loss along laterals accounting for in-line drippers. Several measurements were performed with 12 models of emitters to obtain the experimental data required for developing and assessing the model. Based on the Camargo & Sentelhas coefficient, the model presented an excellent result in terms of precision and accuracy on estimating head loss. The deviation between estimated and observed values of head loss increased according to the head loss and the maximum deviation reached 0.17 m. The maximum relative error was 33.75% and only 15% of the data set presented relative errors higher than 20%. Neglecting local head losses incurred a higher than estimated maximum lateral length of 19.48% for pressure-compensating drippers and 16.48% for non pressure-compensating drippers.

scholarly journals A European-wide <sup>222</sup>Radon and <sup>222</sup>Radon progeny comparison study

2016 ◽  
Author(s):  
Dominik Schmithüsen ◽  
Scott Chambers ◽  
Bernd Fischer ◽  
Stefan Gilge ◽  
Juha Hatakka ◽  
...  
Keyword(s):  
Transport Model ◽  
Atmospheric Transport ◽  
Ground Level ◽  
Data Sets ◽  
Correction Factors ◽  
Comparison Study ◽  
Data Set ◽  
Parallel Data ◽  
Linear Regressions ◽  
Atmospheric Transport Model

Abstract. A European-wide 222Radon/222Radon progeny comparison study has been conducted in order to determine correction factors that could be applied to existing atmospheric 222Radon data sets for quantitative use of this tracer in atmospheric transport model validation. Two compact and easy-to-transport Heidelberg Radon Monitors (HRM) were moved around to run for at least one month at each of the nine European measurement stations that were included in the comparison. Linear regressions between parallel data sets were calculated, yielding correction factors relative to the HRM ranging from 0.68 to 1.45. A calibration bias between ANSTO (Australian Nuclear Science and Technology Organisation) two-filter radon monitors and the HRM of ANSTO/HRM = 1.11 ± 0.05 was found. For continental stations, which use one-filter systems, preliminary 214Po/222Rn disequilibrium values were estimated to lie between 0.8 at mountain stations (e.g. Schauinsland) and 0.9 at non-mountain sites for sampling heights around 20 to 30 m above ground level. Respective corrections need to be applied to obtain a consistent European 222Radon data set for further applications.

scholarly journals MEASURING THE ENVIRONMENTAL PERFORMANCE OF COUNTRIES BY CODAS AND TOPSIS METHODS: G7 GROUP COUNTRIES EXAMPLE

2021 ◽  
Vol 9 (59) ◽  
Keyword(s):  
Environmental Protection ◽  
Performance Index ◽  
Environmental Performance ◽  
Topsis Method ◽  
Data Set ◽  
Future Studies ◽  
Environmental Performance Index ◽  
Two Factors ◽  
The Usa ◽  
Very High

With the awareness of their environmental performance, countries can provide strategies and policies to improve their environmental performance. Thus, countries can contribute to their own economic development by increasing their environmental performance. Therefore, measuring the environmental performance of countries is of great importance. Environmental performance of countries can be measured by the Environmental Performance Index (EPI). EPI consists of two factors, environmental health and ecosystem vitality. Its factors are environmental protection components, and environmental protection components are environmental protection variables. In this context, the research has two purposes. The first of these,To measure the latest and up-to-date environmental performances of the G7 group countries for 2018, using CODAS and TOPSIS multi-criteria decision-making methods (MCDM) over the values of EPI components. The second is to determine which MCDM method can be used to explain the EPI values of countries the most. According to the findings, the ranking of countries' environmental performance with the CODAS method was determined as England, France, Japan, Germany, Canada, Italy and the USA. According to the TOPSIS method, this ranking was determined as England, France, Germany, Japan, Canada, Italy and the USA. According to another finding, it has been observed that there is a significant, positive and very high relationship between the EPI values of the countries and the values measured by the CODAS and TOPSIS methods. According to this result, it was evaluated that EPI can be explained by both methods. In addition, it has been concluded that the correlation value between TOPSIS values of EPI within the scope of the research is higher than the CODAS method, so it can be explained better with the TOPSIS method compared to the EPI CODAS method. In the literature, in order not to find a study measuring the environmental performance of countries with CODAS and TOPSIS methods, it was evaluated that the study in question contributed to the literature, since the findings obtained as a result of the research became a data set for future studies. Keywords: Environmental Performance, Environmental Performance Index, CODAS, TOPSIS

scholarly journals UTTARAKHAND COVID-19 CASES AND DEATHS: COMPARING THE DEMOGRAPHICS AND SUGGESTIVE STRATEGY TO PREVENT SIMILAR PANDEMICS IN FUTURE

2021 ◽  
Author(s):  
Gaurav Joshi ◽  
Akshara Pande ◽  
Omdeep Gupta ◽  
Anoop Nautiyal ◽  
Sanjay Jasola ◽  
...  
Keyword(s):  
World Bank ◽  
Growth Rates ◽  
Human Life ◽  
Set Covering ◽  
World Bank Group ◽  
Data Set ◽  
Bank Group ◽  
Very High ◽  
Pharmaceutical Interventions ◽  
Analyze Data

Coronavirus disease 19 (Covid-19) is causing a dramatic impact on human life worldwide. As of June 11 2021, later one has attributed more than 174 million confirmed cases and over 3.5 million deaths globally. Nonetheless, a World Bank Group flagship report features Covid-19 induced global crisis as the strongest post-recession since World WarII. Currently, all approved therapeutics or vaccines are strictly allowed for emergency use. Hence, in the absence of pharmaceutical interventions, it is vital to analyze data set covering the growth rates of positive human cases, number of recoveries, other factors, and future strategies to manage the growth of fatal Covid-19 effectively. The Uttarakhand state of India is snuggled in the lap of the Himalayas and occupies more people than Israel, Switzerland, Hong Kong, etc. This study analyzed state Covid-19 data, fetched from an authenticated government repository using Python 3.9 from April 1, 2020, to February 28, 2021. The highest recovery rate was attributed to the hilly district Rudraprayag. The analysis also revealed that a very high doubling rate was seen during the last week of May to the first week of Jun 2020. At last, based on this blueprint, we have suggested 6-points solutions for preventing the next pandemic.

Collecting training data to map forest management at global scale

2021 ◽  
Author(s):  
Myroslava Lesiv ◽  
Dmitry Schepaschenko ◽  
Martina Dürauer ◽  
Marcel Buchhorn ◽  
Ivelina Georgieva ◽  
...  
Keyword(s):  
Forest Management ◽  
High Resolution ◽  
Remotely Sensed ◽  
Global Scale ◽  
Google Earth ◽  
Training Data ◽  
Tree Cover ◽  
Data Set ◽  
The World ◽  
Very High

&lt;p&gt;Spatially explicit information on forest management at a global scale is critical for understanding the current status of forests for sustainable forest management and restoration. Whereas remotely sensed based datasets, developed by applying ML and AI algorithms, can successfully depict tree cover and other land cover types, it has not yet been used to depict untouched forest and different degrees of forest management. We show for the first time that with sufficient training data derived from very high-resolution imagery a differentiation within the tree cover class of various levels of forest management is possible.&lt;/p&gt;&lt;p&gt;In this session, we would like to present our approach for labeling forest related training data by using Geo-Wiki application (https://www.geo-wiki.org/). Moreover, we would like to share a new open global training data set on forest management we collected from a series of Geo-Wiki campaigns. In February 2019, we organized an expert workshop to (1) discuss the variety of forest management practices that take place in different parts of the world; (2) generalize the definitions for the application at global scale; (3) finalize the Geo-Wiki interface for the crowdsourcing campaigns; and (4) build a data set of control points (or the expert data set), which we used later to monitor the quality of the crowdsourced contributions by the volunteers. We involved forest experts from different regions around the world to explore what types of forest management information could be collected from visual interpretation of very high-resolution images from Google Maps and Microsoft Bing, in combination with Sentinel time series and Normalized Difference Vegetation Index (NDVI) profiles derived from Google Earth Engine (GEE). Based on the results of this analysis, we expanded these campaigns by involving a broader group of participants, mainly people recruited from remote sensing, geography and forest research institutes and universities.&lt;/p&gt;&lt;p&gt;In total, we collected forest data for approximately 230 000 locations globally. These data are of sufficient density and quality and therefore could be used in many ML and AI applications for forests at regional and local scale.&amp;#160; We also provide an example of ML application, a remotely sensed based global forest management map at a 100 m resolution (PROBA-V) for the year 2015. It includes such classes as intact forests, forests with signs of human impact, including clear cuts and logging, replanted forest, woody plantations with a rotation period up to 15 years, oil palms and agroforestry. The results of independent statistical validation show that the map&amp;#8217;s overall accuracy is 81%.&lt;/p&gt;

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