Academic literature on the topic 'XRF data'

X-ray diffraction (XRD) and X-ray fluorescence (XRF) are widely used analytical techniques for materials characterization; the information they provide can be considered complementary, as the former is mostly used to obtain crystallographic information and analyze phase content, whereas the latter is sensitive to elemental composition. Many researchers and technologists working in a variety of application fields already use them together in some sort of a “combined” approach, by separately performing XRD and XRF data collection and analysis on the same sample and then comparing the analytical results obtained to integrate and complement the respective analytical information. In this work, we propose a true combined approach to merge both XRD and XRF data acquisition and analysis. Custom analytical X-ray instrumentation has been developed to perform the simultaneous data acquisition, by using a single X-ray source and dedicated detectors to collect the diffracted and fluorescent X-ray photons from the same sample volume. Additionally, a combined XRD/XRF data analysis methodology has been implemented by extending Rietveld based code to incorporate the full pattern fitting of XRF spectra starting from the phases instead of a simple matrix elemental composition. We report two analytical examples from different application fields to better illustrate the capabilities of the proposed approach.

As in other fields of spectroscopy, software for x-ray fluorescent analysis has to assist the user in instrument control, raw data refinement, qualitative interpretation of spectral data, and computations for obtaining quantitative results. From a historical point of view, instrument automation and data evaluation routines tor large numbers of samples have been a most important incentive for the introduction of computers into x-ray analysis.

X-ray diffraction-X-ray fluorescence (XRD-XRF) data sets obtained from surface scans of synthetic samples have been analysed by means of different data clustering algorithms, with the aim to propose a methodology for automatic crystallographic and chemical classification of surfaces. Three data clustering strategies have been evaluated, namely hierarchical, k-means, and density-based clustering; all of them have been applied to the distance matrix calculated from the single XRD and XRF data sets as well as the combined distance matrix. Classification performance is reported for each strategy both in numerical form as the corrected Rand index and as a visual reconstruction of the surface maps. Hierarchical and k-means clustering offered comparable results, depending on both sample complexity and data quality. When applied to XRF data collected on a two-phases test sample, both algorithms allowed to obtain Rand index values above 0.8, whereas XRD data collected on the same sample gave values around 0.5; application to the combined distance matrix improved the correlation to about 0.9. In the case of a more complex multi-phase sample, it has also been found that classification performance strongly depends on both data quality and signal contrast between different regions; again, the adoption of the combined dissimilarity matrix offered improved classification performance.

XRF intensity computations, for polychromatic x-ray sources and multicomponent samples, need a high number of low speed floating-point operations, making them a hard bone for any computer. The evaluations of the Intensity expression require the computation of complex attenuation coefficients. They involve also a spread quantity of atomic data for a high number of elements. And the users need to insert additional information on the experiment, like the excitation-detection geometry or the x-ray tube spectrum, interactively. Personal computers are an optimum target for this kind of application mainly due to the low cost of the computation time and the possibility to display high-resolution graphics. Moreover the increasing power of microprocessors makes it possible to attack hard computations like this on a PC.

AbstractAcquisition of new x—ray fluorescence (XRF) hardware or a data reduction computer can be a particularly frustrating experience for analysts who depend upon programs not supplied by the XRF spectrometer manufacturer. Computerized data collection and reduction pragrams generated for a particular spectrameter/computer system can become virtually useless when a significant part af the spectrometer/computer system is replaced. The problem is compounded in a research environment where many different kinds of samples are encountered and many unique analysis programs developed.The potential magnitude of this problem was recently demonstrated at the Ford Motor Company Scientific Research Laboratory when the thirteen year old computer-contolled XRF analysis system was replaced by a new state-of-the-art spectrometer/computer system.

Abstract A prototype instrument, which provides x-ray powder diffraction and x-ray fluorescence analysis in a compact unit, has been developed to support the needs of NASA for planetary exploration. The instrument uses a 9-watt Fe-anodc x-ray tube and CCD in a fixed geometry for recording powder patterns with a 2θ range of 35°. The fluorescence spectrum for elements below Fe is collected simultaneously with the diffraction data. A shuttered Cd-109 isotopic source with emissions at 22 and 80 keV is used to excite higher energy fluorescence. The low-energy limit for discriminating single photon events was found to be ∼1.5 keV. Al-K could be distinguished from a pure sample, but the spectrum below 6 keV was degraded by the read noise of the CCD, which introduced spectral artifacts. Diffraction peaks from halite had a FWHM of ∼1°(2θ), with major contributions to the width from the use of slit collimation on the source and the low tilt angle of the sample.

Owing to the complex matrix effects, the current approach to quantitative X-ray diffraction (XRD) and X-ray fluorescence (XRF) analyses of mixtures requires calibration lines from standards, and is hence tedious and time consuming. New insights reveal that both the matrix effects and the calibration lines can be eliminated mathematically. Any complex mixture can be transformed into a set of simple binary mixtures. One straightforward formula decodes both XRD and XRF. A single XRD or XRF scan quantifies the chemical compounds or chemical elements in any mixture. The unified and simplified procedure reduces by some 80% the laboratory work associated with current practice. Five sets of experimental data are presented to verify its applications. Statistical evaluation of this new procedure gives a precision of ±5% or better, which is normally expected from XRD and XRF analyses.

AbstractIt will be demonstrated that the Lachance-Traill, and Lucas-Tooth and Price matrix correction algorithms can easily be applied to spreadsheet stored XRF data.The structure of spreadsheet stored data in Quantitative XRF Analysis, the utilization of built-in spreadsheet functions essential for data processing and the utilization of Spreadsheet Graphics for plotting of corrected and uncorrected XRF data will be presented.Development of modern Electronic Spreadsheets has reached the point where they can readily be used for almost any type of laboratory task, including: Data Plotting, Statistical Data Analysis, Report Writing and Publishing, Slide Presentations, etc. This valuable tool can easily be added to older equipment that usually lacks sophisticated XRF software. It can also become an auxiliary tool to modern XRF spectrometers equipped with advanced XRF software.The spreadsheet approach gives the analyst freedom of choice to process data according to personal/analytical preferences circumventing the rigidity of software supplied with the equipment. The spreadsheet approach also possesses educational value since it presents the basic ingredients of Matrix Correction in clear and concise table fashion. Addrtionaliy, the spreadsheet program is an excellent tool for demonstrating and evaluating different matrix correction models commonly used in X-ray Spectroscopy.It will also be shown tliat Spreadsheet Graphics are capable of handling the two-theta scans of XRF or XRD data gathered from older DEC/PDP-11 based Rigaku Equipment. This results in excellent hard copies of the two-theta scans, regardless of the output device.A mathematical background leading to the spreadsheet approach was partially presented in the paper “A mathematical comparison of the Lachance-Traill Matrix correction procedure with statistical multiple linear regression analysis in XRF applications” (41st Annual Denver X-ray Conference, Colorado Springs, 1992).

The Itrax core scanner provides rapid, high resolution, non-destructive sediment core analysis using x-ray fluorescence (XRF) spectrometry and x-radiography. The effect of varying instrument settings are explored. Effects of sample properties on XRF data are tested and the uncertainty in XRF data is considered. Existing methods of quantifying XRF data are evaluated. Comparisons are made with other XRF micro-scanners. Finally, the x-radiographic capability of the Itrax core scanner is compared to x-ray computed tomography. Itrax XRF data is generally optimised by use of a 30kV x-ray tube voltage. Current should be set as high as possible without generation of sum peaks (30mA is often a good value). A chromium anode tube is suitable for use with most samples. Water content has a diluting effect on detected peak areas, but it is shown that the effect can be corrected, removing an obstacle to quantification of Itrax data. Water content can be determined non-destructively from the ratio of incoherent to coherent scatter of characteristic radiation from the x-ray tube anode. Surface slope can change recorded peak areas, but a simple model is developed to correct for this effect. Surface roughness increases variability in data and, if the scale of roughness is similar to the beam size, elemental peak areas may be reduced. The presence of a mixture of grain sizes greatly reduces peak areas for elements in the larger grains. The uncertainty in Itrax data is found to be higher than suggested by the conventional estimate that uncertainty is equal to the square root of the peak area. This information is vital for researchers to decide what significance they should attach to variations in Itrax elemental profiles. Quantification methods for core scanner XRF data are compared and an approach using log-ratio transformations determined to be the best. Additionally, an improved entirely non-destructive, quantification approach is presented in which explicit corrections are made for the diluting effect of water (water content may determined from the ratio of incoherent and coherent scatter of the tube anode characteristic radiation) . Compared to similar instruments, the Itrax core scanner is more tolerant of surface imperfections. Its x-radiographic scanning helps to determine the significance and extent of features revealed in XRF data. Itrax x-radiography provides no match for the level of detail that can be obtained using x-ray computed tomography and is not readily quantified. It does however provide information on features below the sample surface and, in masking small variations, can make the main core features more apparent. Users of the Itrax core scanner are provided with quantification of known effects (water content, surface slope; x-ray tube, current and voltage) and are alerted to issues that were not previously widely known (mixing of grain sizes, size of uncertainty in data). The areas of effective use and limitations of the Itrax core scanner are set out and recommendations made for optimising results. An optimal quantification method is identified. Many of the conclusions may have relevance to other XRF core scanners.

Scanning macro-X-ray fluorescence analysis (MA-XRF) is rapidly being established as a technique for the investigation of historical paintings. The elemental distribution images acquired by this method allow the visualization of hidden paint layers and thus, provide insight into the artist's creative process and the painting's conservation history. As a non-destructive instrument MA-XRF and analyzing software PyMca will be used to identify, also to study painting from private collection in Italy. The use of MA-XRF to tentatively predict pigments has an important advantage, its application provides the undamaged and low cost survey of large areas in the painting. The method was proved powerful and useful, capable of efficiently determining the composition and structure of the investigated object in a total safe approach. Nevertheless, for a more throughout evaluation and a better estimation of the pigment composition, it has been demonstrated that, the use of complementary analytical techniques is required

The placement of an unconformable surface within a stratal succession affects the interpreted thickness of units and sequences in contact with that surface. Unit thickness influences the interpretation of basin subsidence, paleotopography, diagenesis, and depositional style. Accurate placement of an unconformity results in true formational thicknesses for formations associated with that unconformity. True thicknesses aid in producing more precise surface to subsurface correlations, isopach maps, and paleogeographic maps. An unconformity may be difficult to identify in the stratal succession due to similar rocks above and below the unconformity and the presence of multiple candidate surfaces. Using statistical discriminant analysis of XRF data, formations bounding an unconformity can be discriminated by elemental composition which results in delineation of the associated unconformity. This discrimination is possible even for rocks that do not have significant differences in provenance if they have experienced distinct diagenetic histories. Elemental differences can be explained by quantity and type of cement. Three discriminant models were created. These models were tested with samples from three formations of similar facies, appearance, and provenance that are all associated with the same regional unconformity. All data, regardless of location, facies, or tectonic feature were used to create the first model. This model achieved moderate success by correctly classifying 80% of known samples. In a second model, data were grouped by facies trends. Separating the data by facies resulted in 94% of known samples being correctly classified. This model was most useful for delineation of an unconformity and discrimination of formations. A third model based solely on location or local tectonic feature produced the best results statistically. 96% of known samples were classified correctly. This third model does not compare locations to each other, thus making it less robust. This last model contributes by adding detail to interpretations made with the facies trend model.

Since the mid 1980s, Raman and X-ray fluorescence spectroscopy have become instrumental techniques that can be easily and successfully applied to chemical analysis. In this respect, scientific studies of works of art and the materials used in their creation are one of the fields that have received great impulse.
Several reasons for the spectroscopic investigation of antiquities and art objects can be pointed out. One of them is the interest in the materials and techniques in use during a certain period or region. This knowledge may be utilized for roughly dating the art object (retrieving pigments with a known date of invention may indicate that the artifact dates from a more recent period). Another reason is that this analysis is a useful source of information during a restoration or conservation treatment, and signs of a previous restoration, retouching or even forgeries can be found.

At the beginning of this century investigation in cultural heritage became an important research field that posed great scientific interest, requiring unprecedented interdisciplinary knowledge of a wide spectrum of areas such as history, archaeology, physics, chemistry, engineering, chemometrics and many other disciplines. On the other hand, improvements in the instrumental techniques used have been the goal of many important studies. Even more, in this decade the investigation has been focalized on the development of a new generation of instruments which allows the combination of complementary analytical techniques along with the advantage of portable instrumentation. Both improvements permit a robust and non-destructive chemical analysis of works of art which are difficult or impossible to study in a laboratory (highly valuable masterpieces, large paintings, and wall paintings).
Chemometrics methods are the necessary complement to these instrumental improvements. In order to maximize the robustness of these instruments, automatic and robust data processing tools are needed to obtain the maximum possible information from a work of art.
This doctoral thesis presents a framework to perform data-fusion systems for classification analysis of pigments investigated in the field of cultural heritage. These systems were developed and evaluated within a European Community research project, the main objective of which was to develop a portable micro Raman and micro X-ray fluorescence instrument (PRAXIS).

The general aim of this doctoral thesis is to study different strategies for the implementation of Raman-XRF data-fusion systems, in order to improve classification analysis of pigments investigated in the field of cultural heritage. This study takes into account the nature of the different interferences usually encountered in these types of signals and its elimination by developing dedicated algorithms. Moreover, this study evaluates automation in classification analysis by developing inference systems.


In order to reach that global aim these particular objectives are defined:

1) To study the nature of stochastic events and signal interferences present in Raman and XRF spectroscopy in order to enable the implementation of chemometrics techniques for classification. This is done in more detail for Raman data, due to the fact that this technique is mainly used in this field for "fingerprint" analysis. The methodology used is Wavelet transform and the improvements achieved in this area are presented in a paper entitled Noise and background removal in Raman spectra of ancient pigments using wavelet transform.
2) To establish the capabilities of a fuzzy logic system for automatic pigment identification. This issue is presented in a paper entitled Fuzzy logic for identifying pigments studied by Raman spectroscopy.
3) To review the current state-of-art of data-fusion in analytical chemistry and to establish actual data-fusion methodologies onto a Raman-XRF sensor fusion system. The performance of each data-fusion architecture is discussed in a paper entitled Micro Raman and X-ray fluorescence spectroscopy data fusion for the classification of ochre pigments.
4) To improve data-fusion methodologies by dual-domain analysis achieved by Wavelet transform. The achievements are presented in two papers Data fusion and dual-domain classification analysis of pigments studied in works of art and Data fusion in the wavelet domain by means of fuzzy aggregation connectives.
5) To define the necessary parameters and propose a methodology to implement data-fusion strategies in Raman and XRF spectroscopy.

Structure

The thesis has been structured in different chapters, each one containing the following information:

Chapter 1 is a theoretical chapter; the first part gives an overview of the basic concepts and latest advances in the fields of micro-Raman spectroscopy and micro-X ray fluorescence spectrometry. The characteristics of a new instrument which combines both techniques are presented along with the improvements achieved in that area. In the second part, the background of chemometrics techniques used in this work is presented.

Chapter 2 introduces the framework for the study of ancient pigments. It describes the nature of samples analyzed and gives an overview of the different techniques used in the creation of works of art throughout the years. Finally, the instruments used in this doctoral thesis for preliminary and final validation analysis are described.

Chapter 3 deals with the data pre-treatment needed before applying chemometric techniques, both for classification and data-fusion. In that respect, the first part focuses on the principles of Wavelet transform as a tool to eliminate signal interferences. This chapter includes a paper in which the development of an innovative method to eliminate noise and background signals from Raman spectra simultaneously is presented. It has been successfully applied for Raman spectra of ancient pigments.

Chapter 4 presents a preliminary study of automatic analysis of pigments by means of soft computing solutions such as Fuzzy logic. A published paper is presented in which Fuzzy logic is used to perform an automatic system for pigment identification. This study is extended to a fusion model and X-ray fluorescence analysis data is incorporated in the developed identification system. The ability of fuzzy logic to process imprecise information is described in the last part of this chapter.

Chapter 5 deals with three data-fusion architectures and their analysis by means of hard computing solutions as Principal components analysis (PCA) and Partial least squares - discriminant analysis (PLS-DA). The models are implemented for the classification of a set of ancient pigments from Byzantine iconography. Benefits and drawbacks of each method are pointed out.

Chapter 6 incorporates a new innovative strategy for data-fusion. The fusion of data in the wavelet domain is discussed and two approaches are presented for Raman and X-ray fluorescence data-fusion: Mid-level and High level dual domain data-fusion. Both are used and successfully applied for the automatic identification of pigments in classification problems with different levels of difficulty. Two papers are included in which both methods are used for the classification of ancient pigments, which face difficult identification problems. These two methods combine the benefits described in the previous chapters of this thesis with the consequent improvement of classification results. The developed systems are suitable to perform a rapid and automatic classification of ancient pigments.

Chapter 7 presents a review of the state of the art regarding data-fusion. The different steps necessary to achieve a proper data fusion are discussed.

Finally, Chapter 8 presents the conclusions of the thesis and suggests some possible issues for future research.




Fusión de datos en espectroscopias Raman y de fluorescencia de rayos X para la identificación de pigmentos en trabajos de arte
Desde mediados de los años 80s, las espectroscopias Raman y de fluorescencia de rayos X (XRF) se pueden considerar técnicas instrumentales de fácil aplicación en el análisis químico. Uno de los ámbitos de gran aplicación de dichas técnicas se centra en el estudio científico de una obra de arte y de los materiales utilizados en su creación.
Existen varias razones para la investigación de antigüedades y objetos de arte por medio de técnicas espectroscópicas. Una de ellas es el estudio de los materiales y técnicas aplicados durante un cierto período o en una determinada región. Este conocimiento puede ser muy útil para ubicar aproximadamente un objeto de arte en una determinada época o periodo. Otra razón es que este análisis es una importante fuente de información para la restauración o el tratamiento de conservación, y permite encontrar señales de una restauración anterior, de repintado o de falsificaciones.

Desde el comienzo de este siglo, la investigación en el patrimonio cultural se sitúa como un campo de la investigación importante con un gran interés científico. Esta investigación, requiere un importante trabajo multidisciplinario que implica a especialistas en áreas como historia, arqueología, física, química, ingeniería, quimiometría y otras disciplinas. Por otro lado, el objetivo de muchos trabajos científicos y estudios importantes, ha sido el desarrollo y las mejoras en estas técnicas instrumentales de análisis. Más aun, en esta década la investigación está enfocada en el desarrollo de una nueva generación de instrumentos que permiten la combinación de técnicas analíticas complementarias junto con la ventaja de una instrumentación portátil. Ambas mejoras permiten un análisis químico robusto y no destructivo de los objetos de arte, en especial de aquellos en los que resulta difícil o casi imposible de estudiar en un laboratorio. Como por ejemplo obras de arte de gran valor y pertenecientes al patrimonio cultural del país, pinturas de grandes dimensiones y pinturas realizadas en murales.

Los métodos Quimiométricos de análisis son el complemento necesario a estas mejoras instrumentales. Con objeto de aumentar al máximo la robustez de estos instrumentos, es necesario proveerlos de herramientas de procesamiento automáticas y robustas para obtener el máximo de información del objeto bajo estudio.
Esta tesis doctoral, presenta un marco de referencia para realizar fusión de datos para la clasificación e identificación de pigmentos estudiados en el campo de patrimonio cultural. Estos sistemas se desarrollan y evalúan dentro de un proyecto de investigación de la comunidad europea. El objetivo principal de este proyecto ha sido desarrollar un instrumento portátil para realizar espectroscopias Raman y de fluorescencia de rayos-X (PRAXIS).

El objetivo general de esta tesis doctoral es estudiar diferentes estrategias para el desarrollo de sistemas de fusión de datos Raman y XRF para mejorar la clasificación de pigmentos. Este estudio contempla la naturaleza de las distintas interferencias que habitualmente se encuentran en estos tipos de mediciones (espectros) y su eliminación por medio del desarrollo de metodologías adecuadas. También, se evalúa la posibilidad de automatización en el proceso de clasificación.


Para alcanzar este objetivo global, se definen los siguientes objetivos particulares:

1) Estudiar la naturaleza de eventos estocásticos (ruido) e interferencias habitualmente presentes en espectroscopia Raman y XRF, con el fin de facilitar la aplicación de técnicas quimiométricas de clasificación. Este estudio se realiza más profundamente para los espectros obtenidos por espectroscopia Raman, ya que es la técnica principalmente utilizada en este campo para una identificación del tipo "huella digital." La metodología usada es la transformada Wavelet y las mejoras logradas se presentan en un artículo titulado "Ruido y eliminación de señales de fondo en espectros Raman de pigmentos antiguos por medio de la transformada Wavelet".
2) Establecer un sistema de lógica difusa para la identificación automática de pigmentos. Este estudio se presenta en un articulo titulado "Lógica difusa para identificar pigmentos estudiados por espectroscopia Raman".
3) Estudiar la situación actual de aplicaciones y desarrollos de fusión de datos en química analítica y establecer las metodologías de fusión de datos reales en un instrumento Raman-XRF. Los resultados obtenidos en distintos modelos de fusión de datos se discute en un articulo titulado "Fusión de espectros Raman y de fluorescencia de rayos X para la clasificación de pigmentos ocres".
4) Mejorar las metodologías de fusión de datos por medio del análisis en el dominio dual dado por la transformada Wavelet. Los logros obtenidos se presentan en dos artículos "Fusión de espectros y análisis de clasificación en el dominio dual de pigmentos estudiados en obras de arte" y "Fusión de datos en el dominio Wavelet por medio de conectores de agregado difuso".
5) definir los parámetros necesarios y proponer a una metodología llevar a cabo las estrategias de fusión de espectros en espectroscopias Raman y XRF.

Estructura

La tesis ha sido la estructura en capítulos diferentes, donde cada uno contiene la siguiente información:

El capítulo 1 es un capítulo teórico; donde en una primera parte se da una apreciación global de los conceptos básicos y de los últimos adelantos en espectroscopias Raman y de fluorescencia de rayos X. Las características de un nuevo instrumento que combina ambas técnicas se presentan junto con las mejoras logradas en él. En una segunda parte, se describen las técnicas quimiométricas usadas en este trabajo.

El capítulo 2 describe la naturaleza de las muestras estudiadas y de su uso en la creación de obra de arte. Finalmente, se describen instrumentos Raman y XRF usados en esta tesis doctoral.

El capítulo 3 presenta el tratamiento necesario en los datos antes de aplicar las técnicas quimiométricas, ya sea para la clasificación y/o fusión de datos. En ese sentido, se presenta un estudio de la aplicación de la transformada Wavelet como una herramienta para eliminar las interferencias señaladas. Este capítulo incluye un artículo en el que nosotros presentamos el desarrollo de un método innovador para eliminar simultáneamente las señales de ruido y fondo es espectros Raman.

El capítulo 4 presenta un estudio preliminar del análisis automático de pigmentos por medio de la lógica difusa. Se presenta artículo donde la lógica difusa es utilizada para realizar un sistema automático de identificación de pigmentos. Este estudio se extiende a un modelo de fusión y por el cuál la información obtenida por XRF es incorporada en el sistema de identificación desarrollado.

El capítulo 5 presenta tres arquitecturas de fusión de datos y el posterior análisis por medio de técnicas quimiométricas como el análisis de componentes Principal (PCA) y la regresión por mínimos cuadrados parciales para análisis discriminante (PLS-DA). Los modelos se llevan a cabo con el estudio de pigmentos antiguos referidos a la iconografía bizantina. Esta parte acaba señalando los beneficios y desventajas de cada método.

El capítulo 6 presenta una nueva estrategia para la fusión de datos, que es la fusión de datos en el dominio del wavelet. Se discuten los fundamentos y se presentan dos modelos de fusión de datos Raman y XRF en el dominio wavelet: El nivel medio y el nivel alto, ambos se aplican a la identificación automática de pigmentos. Dos artículos son incluidos, donde se describen ambos métodos y se presenta su aplicación para la clasificación de pigmentos antiguos.

El Capítulo 7 presenta un estudio sobre el estado actual en la investigación de fusión de datos y su aplicación en química analítica. Las etapas necesarias para desarrollar métodos apropiados de fusión de análisis.

Finalmente, en el capítulo 8 presenta las conclusiones de la tesis y propone posibles trabajos de investigación futura.

Lithological core logging is a subjective and time consuming endeavour which could possibly be automated, the question is if and to what extent this automation would affect the resulting core logs. This study presents a case from the Zinkgruvan Zn-Pb-Ag mine, Bergslagen, Sweden; in which Classification and Regression Trees and K-means Clustering on the Self Organising Map were applied to X-Ray Flourescence lithogeochemistry data derived from automated core scan technology. These two methods are assessed through comparison to manual core logging. It is found that the X-Ray Fluorescence data are not sufficiently accurate or precise for the purpose of automated full lithological classification since not all elements are successfully quantified. Furthermore, not all lithologies are possible to distinquish with lithogeochemsitry alone furter hindering the success of automated lithological classification. This study concludes that; 1) K-means on the Self Organising Map is the most successful approach, however; this may be influenced by the method of domain validation, 2) the choice of ground truth for learning is important for both supervised learning and the assessment of machine learning accuracy and 3) geology, data resolution and choice of elements are important parameters for machine learning. Both the supervised method of Classification and Regression Trees and the unsupervised method of K-means clustering applied to Self Organising Maps show potential to assist core logging procedures.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
This study aimed the evaluation and application of methodology for multielement analyses by total reflection X-ray fluorescence spectrometry (TXRF) in order to provide analyte concentration measurements with accuracy and precision. Using the energy and intensity of the spectral lines of characteristic X-ray, a series of chemicals were identified and quantified, respectively, with a concentration below part per million to a few parts per billion, especially for transition metals. To ensure statistical reliability and reproducibility, a methodology based on the deposition of fine particles, less than 50 m, representative sample and uniformly spread on a quartz flat reflector, which was extremely clean and positioned at the angular condition of maximum reflectivity of monochromatic X-rays was applied. To ensure uniformity on the support surface and the sample representativeness, a number of replicas of specific quantities of samples, in the form of a fine powder was added in a diluted viscous organic solution containing a well-known concentration of an element choosing as internal standard. An aliquot of the viscous solution containing both the suspended particulate sample and an internal standard was deposited at the center of the quartz reflector and dried, yielding a very thin layer of particulates. First, the instrumental TXRF was previously evaluated for its operation, spectral response and recovery of transition metal concentrations in a test sample supplied by the manufacturer. The reproducibility of the elemental concentration measurements was tested with a combination of the number of experimental replicates (five) and analytical (three) for each type of environmental matrix samples, namely certified reference materials or CRMs. Six types of CRMs were tested: river sediment, tomato leaves, rice, fish muscle, bone and bovine liver. The data were statistically processed data, resulting in a series of average and uncertainty values of the analyte concentrations was compared to certified reference values, reported in the technical reports of CRM. Regarding the multielement character of the TXRF technique, there was a good recovery, about 100%, for most of the certified concentrations of the referenced analytes in the six CRMs within the margin of variability of results found by both the TXRF technique and reports. It was also found that the detection limit depends on the density matrix of the material under study. However, the transition elements were those with the lowest values of detection limits. Having a good recovery of majority analyte concentrations in Buffalo River sediment reference material, the same methodology was applied to sediment material analysis of Bezerra stream that was collected in three locations and for a period of three years. A number of chemicals has been identified through their spectral lines K and L and quantified following the internal standard method. The set of concentration data was statistically processed from the point of view of the normality of the data and an analysis of principal components, revealing a systematic presence of high concentrations of heavy metals such as lead and chromium, comparatively higher those recommended by current environmental legislation (CONAMA 420/2009) as the maximum permissible limits.
Este trabalho teve como objetivo a avaliação e aplicação de metodologia para análise multielementar por meio da espectrometria de fluorescência de raios X por reflexão total (TXRF), a fim de fornecer medidas de concentração de analitos com acurácia e precisão. Usando a energia e a intensidade das linhas espectrais de raios X característicos, uma série de elementos químicos foram identificados e quantificados, respectivamente, com concentração abaixo de parte por milhão até poucas partes por bilhão, principalmente para metais de transição. A fim de garantir a confiabilidade e reprodutibilidade estatística, foi aplicada uma metodologia que se baseia na deposição de particulados finos, menores que 50 m, representativos da amostra e uniformemente distribuídos sobre um refletor plano de quartzo, previamente limpo, na condição angular de máxima refletividade de raios X monocromáticos. Para garantir a uniformidade no suporte e a representatividade da amostra, uma série de réplicas de quantidades específicas de amostras, na forma de um pó fino, foi adicionada em solução orgânica viscosa diluída contendo uma concentração conhecida de um elemento na qualidade de padrão interno. Uma alíquota da solução viscosa contendo ambos o particulado de amostra em suspensão e o padrão interno foi depositada no centro do refletor de quartzo e seca, obtendo-se uma camada fina de particulado. Primeiramente, o instrumental TXRF foi previamente avaliado quanto a operação, resposta espectral e recuperação de concentrações de metais de transição de uma amostra de teste fornecido pelo fabricante. A reprodutibilidade das medidas de concentração elementar foi testada com uma combinação da série de réplicas experimentais (cinco) e analíticas (três) para cada tipo de matriz de amostras ambientais, chamadas de Materiais de Referência Certificados ou MRC. Foram testados seis tipos de MCRs: sedimento de rio, folhas de tomate, arroz, músculo de peixe, osso e fígado bovino. Foram processados estatisticamente a série de dados de concentrações elementares de cada MCR, obtendo-se o valor médio e incerteza da concentração de cada analito de referência o qual foi comparado ao reportado nos laudos técnicos dos MCR. Considerando o caráter multielementar da técnica TXRF, verificou-se uma boa recuperação, em torno de 100%, da maioria das concentrações referenciadas e certificadas dos analitos nos seis MCRs, dentro da margem de variabilidade dos resultados encontrados pela técnica TXRF e reportados pelos laudos. Verificou-se também que o limite de detecção depende da densidade da matriz do material sob estudo. Contudo, os elementos de transição foram os que apresentaram os menores valores de limites de detecção. Tendo a boa recuperação das concentrações de analitos maioritários no material de referência sedimento Buffalo River, foi aplicada a mesma metodologia para análise de material de sedimento do córrego Bezerra-Cascavel que foi coletado em três locais ao longo dele e por um período de três anos. Uma série de elementos químicos foram identificados através de suas linhas espectrais K e L, e quantificados seguindo o método do padrão interno. O conjunto de dados de concentração foi processado estatisticamente do ponto de vista da normalidade dos dados e feita uma análise de componentes principais, revelando uma sistemática presença de altas concentrações de metais pesados, tais como chumbo e cromo, comparativamente maiores daqueles preconizados pela atual legislação ambiental (CONAMA 420/2009) quanto aos limites máximos permissíveis.

During times with global pandemics and climate change, the need for companies to be able to conduct their business without travelling is essential. Upholding social distancing and complying to restrictions on travel both globally and nationally have not only forced everyone to conduct their business from home but to do so regardless of technological maturity. While also doing so for an unforeseeable future. In times of change, resilience is key. Having more durable and resilient teams and workers are essential now, tomorrow, and most likely in the future too. Improving the usability of remote collaboration has never been as important. Disregarding the fact that this has been a forced act of measure from the government, the aftermath of this for many companies will surely include reduced costs for travel, improved efficiency and reduced environmental impact. Undoubtedly, there is incentive from a business perspective, but what are the effects from the user's perspective? Derived from previous literature on presence, video communication, quality of experience (QoE) and interaction, this case study set out to examine the following research questions; What current factors influence the remote meetings of employees in a telecommunication company? In what way can extended reality (XR) technology potentially improve their experience? Extended reality (XR) technology refers to all real-and-virtual combined environments including augmented reality (AR), mixed reality (MR) and virtual reality (VR) and other areas that exist among them.With obtained data from interviews and a series of tests, the results indicate that factors from every category; human, system and context factors influence the QoE. Additionally, in its current state, XR technology does not provide enough, especially in terms of quality, to significantly improve anything for these employees. The XR technology has potential to heighten the experience in respects such as mobility, but for presence and social context it did not gain much attraction.
Under tider med en global pandemi och klimatfo ra ndringar a r behovet att fo retag ska kunna bedriva sin verksamhetutan att resa stort. Att uppra ttha lla social distansering och fo lja restriktioner pa resor ba de globalt och nationellt harinte bara tvingat alla att bedriva sin verksamhet hemifra n utan att go ra det oavsett teknisk mognad. Det go rs ocksa fo ren ofo rutsebar framtid. I tider av fo ra ndring a r det viktigt att vara anpassningsbar. Att ha mer ha llbara ochmotsta ndskraftiga team och arbetare a r viktigt nu, imorgon och troligtvis a ven i framtiden. Att fo rba ttraanva ndbarheten av samarbete pa distans har aldrig varit lika viktigt.Om man bortser fra n det faktum att detta har varit en pa tvingad a tga rd fra n regeringen, sa kommer konsekvensernafo r ma nga fo retag sa kert att inkludera la gre kostnader fo r resor, fo rba ttrad effektivitet och minskad miljo pa verkan.Utan tvekan finns det incitament ur ett affa rsperspektiv, men vilka a r effekterna ur anva ndarnas perspektiv?Uppbyggt fra n tidigare litteratur om na rvaro, videokommunikation, kvalitet av upplevelsen (QoE) och interaktion,syftar denna fallstudie till att underso ka fo ljande forskningsfra gor; Vilka aktuella faktorer pa verkar distansmo ten fo ransta llda i ett telekommunikationsfo retag? Pa vilket sa tt kan XR-teknik (Extended Reality) potentiellt fo rba ttra derasupplevelse? Med Extended reality (XR) -teknologi menas alla reala-och-virtuella kombinerade miljo er inklusiveAugumented Reality (AR), Mixed Reality (MR) och Virtual Reality (VR) och andra omra den som finns mellan dem.Insamlade data fra n intervjuer och en serie tester visar att faktorer fra n varje kategori; ma nskliga, system- ochkontextuella faktorer pa verkar QoE. I sitt nuvarande tillsta nd, ger XR-tekniken inte tillra ckligt, sa rskilt inte na r detga ller kvalitet, fo r att avseva rt fo rba ttra na got fo r de ansta llda. XR-tekniken har potential att fo rba ttra upplevelsen na rdet ga ller exempelvis ro rlighet, men fo r na rvaro och social kontext har den a n sa la nge inte mycket att bidra med.

La sédimentation marine récente dans les fosses de subduction est caractérisée par l'interstratification de sédiments hémipélagiques et de turbidites localement intercalées avec les coulées de débris, qui peuvent résulter de la destabilisation des pentes continentales par de tremblements de terre. La marge d’Equateur est constituée par une forte érosion tectonique qui contribue à la formation d'une fosse profonde remplie d'une suite complexe de faciès sédimentaires. La sédimentation par écoulements gravitaires est omniprésente le long de la marge et les faciès vont de dépôts de transport de masse d'épaisseur métriques latéralement continus à des turbidites d'épaisseur centimétriques isolées intercalées avec des couches d'hémipélagites, de volcanoclastiques et de téphras. Nous présentons l'interprétation de la bathymétrie, des profils sismiques à haute résolution et des données pétrophysiques des carottes sédimentaires. L'objectif de cette étude est de décrire la complexité morphologique à la frontière équatorienne de la plaque de Nazca où un ensemble d'aspérités marines profondes ont subducté à différentes échelles, et ses conséquences sur la distribution latérale des sédiments dans les différents sous-bassins. La marge équatorienne comprend trois segments géomorphologiques: Le segment nord, situé au nord de la crête Carnegie, est caractérisé par une large (5-10 km) et profonde fosse (3800-4000 m), une pente continentale ravinée et une plate-forme (10-40 km de large) avec subsidence active. Le segment central en face de la crête de Carnégie montre une fosse étroite (0-5 km de large) et peu profonde (3100-3700 m), la pente escarpée et ravinée, sans canyons, et plateau continental étroit de 15 à 40 km de large caractérisé par des zones d'affaissement et de soulèvement actifs. Enfin, le segment sud, situé au sud de la crête Carnegie, présente une large (5-10 km) et profonde fosse (4000-4700 m), une pente continentale pauvre en sédiments avec des systèmes de canyons bien définis et une large plate-forme de subsidence (20-50 km). La dynamique sédimentaire le long de la marge est évaluée par l'analyse de 15 carottes sédimentaires dont la description visuelle, les photographies à haute résolution, l'imagerie par rayons X, les données XRF et les propriétés pétrophysiques conduisent à l'identification de 11 faciès sédimentaires caractérisant 7 processus sédimentaires: dépôts de turbidite, hémipélagites, téphras, dépôts de coulées de débris, homogénites, des slumps et des dépôts de carbonate de ooze. Les âges des dépôts sont définis par la datation au radiocarbone des sédiments hémipélagites. Les âges vont de 500 à 48000 ans BP. Les profils sismiques à haute résolution permettent de définir 3 echo-faciès: transparent, stratifiés et chaotiques. Le facies transparent est principalement associé aux dépôts d'homogénites, le facies stratifié est associé aux dépôts interstratifiés turbiditique-hémipélagique et le facies chaotique est associé à des dépôts gravitaires grossiers. Le remplissage de la fosse représente un enregistrement lacunaire mais important de l'histoire de la marge de subduction. De grandes coulées de débris se déplaçant vers l'est dans les deux séquences inférieures du remplissage de la fosse sont initiées le long de la paroi extérieure de la fosse, le long de grandes failles normales dues à la flexion de la plaque océanique subductante. Les sédiments de la séquence supérieure du remplissage qui nappent la fosse sont plus largement fournis par la paroi interne de la fosse mais avec un fort contrôle de la ride de Carnegie. En conséquence, la profondeur, la fréquence, l'épaisseur, la composition et la disposition latérale des dépôts sédimentaires varient grandement entre le nord et le sud. Les grands méga-lits simples, les slumps, les coulées de débris et les homogénites sont situés dans les segments nord et sud. Ils sont déclenchés par de grands escarpements de failles régionales, dans le Nord
Recent deep marine sedimentation in subduction trenches is characterized by the inter-stratification of hemipelagic and turbidite sediments locally interbedded with debris flow, which can result from continental slope shaking triggered by earthquakes. The active margin of Ecuador comprises tectonic erosion that contributes to the formation of a deep trench filled by a complex suite of sedimentary facies. Gravity flow sedimentation is ubiquitous along the margin and facies range from laterally continuous m-thick mass transport deposits to isolated cm-thick turbidites intercalated with hemipelagite, volcanoclastics and tephra. In this study we show interpretation of swath bathymetry, high-resolution seismic profiles and petrophysical data from cores. The objective is to describe the morphologic complexity on the Ecuadorian border of the Nazca plate where a set of deep marine asperities is subducting at different scales, and their consequences on the distribution of sediments in the different sub-basins. Ecuadorian margin comprises three geomorphological segments: The northern segment, northward of the Carnegie Ridge, is characterized by a wide (5-10 km) and deep trench (3800 – 4000 m), a gentler gullied continental slope and a shelf (10-40 km wide) with active subsidence. The central segment facing the Carnegie Ridge, is strongly influenced by the subduction of the Carnegie ridge which induces a narrow (0–5 km wide) and shallow trench (3100 – 3700 m depth), a steep and gullied slope with no canyons and a 15–40 km wide shelf characterized by areas with active subsidence and uplift. Finally, the southern segment, southward of the Carnegie Ridge, presents a wide (5–10 km) and deep (4000–4700 m) trench, a starved continental slope with well-defined canyon systems and a wide subsiding shelf (20–50 km). The sedimentary dynamics along the margin is evaluated by the analysis of 15 cores. Visual description, high-resolution photographs, X-Ray imagery, XRF data and petrophysical properties led to the identification of 11 sedimentary facies that characterize seven sedimentary processes: turbidites, hemipelagites, tephras, debris flows, homogenites, slumps, and ooze carbonate deposits. Age of the deposits is defined by radiocarbon age dating of hemipelagic sediments. Ages range from 500 to 48,000 years BP. High-resolution seismic profiles allow definition of three echo-facies: transparent, layered and chaotic. Transparent echo-facies is mainly associated to homogenite deposits, layered echo-facies is associated to the turbiditic-hemipelagic interbedded deposits and chaotic echo-facies is associated to reworked gravity flow deposits. The trench fill represents a lacunar but important record of the subduction margin history. Large eastward debris flows in the lower two sequences of the trench fill are provided by the trench outer wall as a results of slope failures along normal faults due to the downward bending of the oceanic plate. The sediment of the upper sequence of the trench fill draping the trench floor, are largely provided by the inner trench wall strongly controlled by the Carnegie Ridge. As a result, depth, frequency, thickness, composition and lateral disposition of the deposits vary greatly from those at north and south. The large, simple mega-beds like slump, debris flows and homogenites are located at the northern and southern segments. They were triggered by large regional faults in the North and enhanced by the activity of sets of splay faults in the South overhanging the seafloor at the slope toe. Small-size, fluid rich events were triggered by subduction of isolated seamounts at the edges of the Carnegie Ridge due to frequent but small destabilizations of an inner trench wall preconditioned by the impacts of successive seamounts. Sets of partly volcanoclastic turbidites in central segment might have been triggered by the complex interaction of slope and continental shelf deformation by seamount subduction

This article demonstrates the utility of Bayesian modelling and inference in financial market volatility analysis, using the 2007-2008 credit crisis as a case study. It first describes the applied problem and goal of the Bayesian analysis before introducing the sequential estimation models. It then discusses the simulation-based methodology for inference, including Markov chain Monte Carlo (MCMC) and particle filtering methods for filtering and parameter learning. In the study, Bayesian sequential model choice techniques are used to estimate volatility and volatility dynamics for daily data for the year 2007 for three market indices: the Standard and Poor’s S&P500, the NASDAQ NDX100 and the financial equity index called XLF. Three models of financial time series are estimated: a model with stochastic volatility, a model with stochastic volatility that also incorporates jumps in volatility, and a Garch model.

ABSTRACT As the pursuit of oil and gas in Middle East Jurassic carbonates reservoirs grows, it is increasingly evident that horizontal wellbore placement, or targeting, plays a first-order role in the production capability of a well. Indeed, the percentage of a wellbore "in target" is a common metric used when evaluating the causes for good or poor production from any particular well. The most common process used for geosteering a horizontal wellbore into a chosen target is the correlation of logging-while-drilling (LWD) total gamma-ray (GR) to a vertical pilot-hole GR log or offset wells GR logs. However, limitations inherent to this procedure can reduce the ability to effectively use LWD GR data due to 4 ½" slim hole diameter and mud telemetry issues, the non-descript signal from LWD tools due to high pressure and high temperature and the possibility of lost signal from LWD tools. In addition, the thickness of MRW-F11 targeted reservoir is limited to plus or minus 22 ft and low GR contrast from bed to bed might lead to loss of directional control in the target MRW-F11. To accurately geosteer a well, Geochemical analyses of drilled cuttings are proposed to assist well placement. The analyses performed were elemental data derived from energy-dispersive X-ray fluorescence (ED-XRF) and mineralogical quantitative content acquired from the direct measurement from energy-dispersive X-ray Diffraction (ED-XRD). The Elemental and mineralogy data were acquired from drilling cuttings taken at ten feet intervals, from two offsets wells. The mineral and elemental data were used to build a chemo-stratigraphic profile and zonation of the sedimentary section. Chemo-stratigraphic zones are defined as having multiple elements and keys ratios (where possible) which illustrate distinct changes in chemical and mineralogical composition profiles from one zone to another. These zones were correlated over reasonable distances (at a minimum the length of the horizontal wellbore) and can be readily identifiable in cuttings. Using these criteria chemo-stratigraphic zonation's have been constructed in the Middle Marrat formation going from MRW-F1 toward MRW-F11 layer. Well site ED-XRF and ED-XRD data were used in conjunction with LWD Gamma Ray to geosteer at approximately 22 feet thin zone which resides at the base of an approximately 100 ft thick reservoir carbonate section of the main MRW-F11 reservoir. The LWD GR Signal was 45 ft behind the bit while all XRF and XRD data were at plus or minus 5 feet while sliding at plus or minus 10 ft in rotary mode and with a controlled slow rate of penetration (ROP) of 10 ft/hr. Geochemical rock analyses (GEAR) using XRF & XRD chemical analyses was the unique reference for approximately 500 ft interval to geosteer the well when LWD lost the signal, wiper trip was cancelled which considerably reduced drilling costs. Well site XRF and XRD data was successfully applied to geosteer the well, determine the position of the wellbore in zones of non-descript LWD GR signature, and determine the lateral extent of the reservoir interval.

The development of satellite imaging technology that has spectral capability has the potential to be utilized in hydrocarbon exploration. The presence of hydrocarbons can be detected through spectral recording of hydrocarbon seepage. Over a long period, hydrocarbon seepage will change the chemical structure and mineralogy of the surrounding soil and rocks, so that it will cause spectral anomalies that are key to the existence of active hydrocarbons and petroleum systems. The West Kendeng zone was chosen as a research location because several hydrocarbon seepage sites were found to contain, either oil or gas in the area. Based on hydrocarbon seepage spectral theory, Landsat 8 imagery has a wavelength spectrum capability that is sensitive to the anomalous object of hydrocarbon seepage. Therefore, this research was conducted to determine the distribution of hydrocarbon seepage areas in the West Kendeng zone by using Landsat 8 imagery. In addition to using Landsat 8, to strengthen the research results a surface geological mapping process was also carried out at the seepage location. Then the samples obtained were analyzed by XRD and XRF. XRD analysis was carried out to determine the types of minerals that became an anomaly around the seepage location. In addition, the XRF analysis is carried out to determine the chemical composition of rocks that have undergone alteration. Based on the results of Landsat 8 data calibration, an altered rock which is an anomaly of hydrocarbon seepage is found in the south and southwest of the study site. These results are confirmed by the location of the discovery of several points of seepage of hydrocarbons in the research area. The XRD test results also showed anomalous clay mineral content in the form of halloysite, albite, and augite in the southwest and south of the study site. Besides this anomaly, magnetite and pyrite were also found at that location. While the XRF test results from the sample also showed the presence of Fe2O3 element at 9.21% and CaO at 7.42% in the south and southwest of the study location. This indicates a reaction between hydrocarbons and rocks that affect the acidity conditions around them, so they will form clay minerals, iron oxides, and iron sulfides. Therefore, based on Landsat 8 image analysis, XRD, and XRF, a hydrocarbon seepage distribution area accumulated in the Bancak, Boto, Wonokerto, and Nyemoh areas in the Semarang Regency.

Abstract The article presents the results of identification and quantitative analysis of the phase composition, fine structure parameters of minerals in carbonate and terrigenous rocks by the use of modern X-ray diffraction (XRD) analysis. To make the XRD analysis, we optimized the modes of x-ray pattern shooting by changing the radius of the goniometer, the system of primary and secondary slits, Soller slits, and the system of detecting the low-content minerals. In processing the obtained x-ray patterns, we considered the size and defects of the crystal grains, the crystallographic mode of arrangements, atomic population of the crystal lattice, the Debye-Waller factor and the instrumental line broadening by the use of the Caliotti function for LaB6. So we determined the type and content of minerals, estimated the period of the crystal lattice, the size of the coherent scattering domains and micro-distortion crystal lattice of the mineral. We compared the obtained data on the presence and quantitative content of minerals with the data of X-ray fluorescence (XRF) analysis and scanning electron microscopy (SEM). Based on the obtained data, reference intensity ratio (RIR) coefficients were selected for a number of minerals typically contained in core materials for quantitative phase analysis by the use of the corundum number method.