Rietveld refinement with wavelet compressed data sets

1999 ◽  
Vol 214 (8) ◽  
Author(s):  
L'. Smrčok
Keyword(s):  
Rietveld Method ◽  
Significant Loss ◽  
Quantitative Phase Analysis ◽  
Discrete Wavelet ◽  
Data Sets ◽  
Rare Sugar ◽  
Rietveld Refinements ◽  
Speed Up ◽  
Time Savings ◽  
Compressed Data

AbstractCrystal structures of highly ordered triclinic kaolinite, cubic hexamethylentetramine and a part of the structure of monoclinic rare sugar were refined by Rietveld method using wavelet compressed sets of intensities. Compression of intensities sets was accomplished by a discrete wavelet transform (DWT). It was found that accuracy of refined positional parameters did not change significantly even if the compression ratio reached 8:1. Similarly, quantitative phase analysis done by Rietveld method provided very close estimates of phase composition for compression ratios 2:1 and 4:1.Application of DWT compressed data led to time savings approaching 50–60% without significant loss of information. This procedure may accelerate molecular modelling based on powder data, or speed up introductory steps of Rietveld refinements with extensive data/parameters sets.

A New Method for Characterizing Replacement Rate Variation in Molecular Sequences: Application of the Fourier and Wavelet Models to Drosophila and Mammalian Proteins

Genetics ◽  
2000 ◽  
Vol 154 (1) ◽  
pp. 381-395
Author(s):  
Pavel Morozov ◽  
Tatyana Sitnikova ◽  
Gary Churchill ◽  
Francisco José Ayala ◽  
Andrey Rzhetsky
Keyword(s):  
Wavelet Transforms ◽  
Parametric Bootstrap ◽  
Real Data ◽  
New Method ◽  
Rate Variation ◽  
Discrete Wavelet ◽  
Data Sets ◽  
Ratio Test ◽  
Replacement Rate ◽  
New Models

Abstract We propose models for describing replacement rate variation in genes and proteins, in which the profile of relative replacement rates along the length of a given sequence is defined as a function of the site number. We consider here two types of functions, one derived from the cosine Fourier series, and the other from discrete wavelet transforms. The number of parameters used for characterizing the substitution rates along the sequences can be flexibly changed and in their most parameter-rich versions, both Fourier and wavelet models become equivalent to the unrestricted-rates model, in which each site of a sequence alignment evolves at a unique rate. When applied to a few real data sets, the new models appeared to fit data better than the discrete gamma model when compared with the Akaike information criterion and the likelihood-ratio test, although the parametric bootstrap version of the Cox test performed for one of the data sets indicated that the difference in likelihoods between the two models is not significant. The new models are applicable to testing biological hypotheses such as the statistical identity of rate variation profiles among homologous protein families. These models are also useful for determining regions in genes and proteins that evolve significantly faster or slower than the sequence average. We illustrate the application of the new method by analyzing human immunoglobulin and Drosophilid alcohol dehydrogenase sequences.

Conductivity Characterizationof Iron Oxide Doped 8 mol% Yttria Stabilized Zirconia

2018 ◽  
Vol 280 ◽  
pp. 58-64
Author(s):  
Tinesha Selvaraj ◽  
Johar Banjuraizah ◽  
S.F. Khor ◽  
M.N. Mohd Zainol
Keyword(s):  
Solid Oxide Fuel Cells ◽  
Solid Electrolytes ◽  
Electrode Materials ◽  
Rietveld Method ◽  
Quantitative Phase Analysis ◽  
X Ray Diffraction ◽  
Solid Electrode ◽  
Short Sample ◽  
X Ray ◽  
Rietveld Quantitative Phase Analysis

A facile strategy was proposed to incorporate the dopant Fe into 8YSZ-based material, which can be potentially applied as solid electrode materials for Solid Oxide Fuel Cells (SOFC). In this study, 8YSZ powder was investigated in terms of densification, conductivity and thecrystal structure as a solid electrolytes. Therefore, varying mol% of Fe included 1, 2, and 3 were prepared for investigation. The crystalline structure of the pristine and Fe doped samples were characterized by X-ray diffraction (XRD) and the phase contents were evaluated by using the Rietveld method. Rietveld quantitative phase analysis demonstrates that the monoclinic-ZrO2phase increases (12.8 wt% to 39.7 wt%) as the concentration of Fe increases, while the amount of tetragonal-ZrO2phase drop (40.4 wt% to 11.9 wt%) dramatically. Sintering activity was applied to improve incorporation of the 8YSZ powder and the dopant Fe where the relative density increases from 77% to 92%. Sample YSZ-2Fe has been fitted with CPE equivalent circuit and achieved 6.251 x 10-6S/cm at 300 °C in air. However, it was found that conductivity levels decreased as the mol% of Fe increased. In short, sample YSZ-2Fe ceramic demonstrated good results in terms of densification (92.09%), cubic ZrO2phase (22 wt%) and conductivity 6.251 x 10-6S/cm.

Recent Developments in Gradient Plasticity—Part II: Plastic Heterogeneity and Wavelets

2002 ◽  
Vol 124 (3) ◽  
pp. 358-364 ◽  
Author(s):  
Avraam A. Konstantinidis ◽  
Elias C. Aifantis
Keyword(s):  
Spatial Distribution ◽  
Wavelet Analysis ◽  
Gradient Theory ◽  
Discrete Wavelet ◽  
Experimental Measurements ◽  
Data Sets ◽  
Gradient Plasticity ◽  
Slip Step ◽  
Recent Developments ◽  
Heterogeneous Deformation

Wavelet analysis is used for describing heterogeneous deformation in different scales. Slip step height experimental measurements of monocrystalline alloy specimens subjected to compression are considered. The experimental data are subjected to discrete wavelet transform and the spatial distribution of deformation in different scales (resolutions) is calculated. At the finer scale the wavelet analyzed data are identical to the experimental measurements, while at the coarser scale the profile predicted by the wavelet analysis resembles the shear band solution profile provided by gradient theory in agreement with experimental observations. The different data sets provided by wavelet analysis are used to train a neural network in order to predict the spatial distribution of strain at resolutions higher than those possible by the available experimental probes. In addition, applications of wavelet analysis to interpret size effect data in torsion and bending at the micron scale are examined by deriving scale-dependent constitutive equations which are used for this purpose.

scholarly journals Structural Properties Analysis of Mg-β-TCP by X-ray Powder Diffraction with the Rietveld Refinement

2020 ◽  
Vol 9 (4) ◽  
pp. 1562-1568
Keyword(s):  
Powder Diffraction ◽  
Rietveld Method ◽  
Quantitative Phase Analysis ◽  
Structural Refinement ◽  
Osteoporosis Therapy ◽  
X Ray ◽  
Cell Parameters ◽  
Biomineralization Process ◽  
Resultant Powder ◽  
Rapid Reaction

The incorporation of magnesium in the synthetic apatite has been associated with the biomineralization process and osteoporosis therapy in humans and animals. β-tricalcium phosphate (β-TCP) is one of the most common bioceramics widely applied in bone cement and implants. In this work, Ca-deficient apatite (CDA) with a theoretical 0.08 Mg/(Ca+Mg) ratio was synthesized by the rapid reaction between Ca(OH)2, MgCl2.6H2O and H3PO4 at 40°C and the resultant powder calcined at 650 °C for 10h. X-ray powder diffraction analysis (XRD), in combination with the Rietveld method (Fullprof-suite), was employed for quantitative phase analysis and structural refinement. The results of XRD indicate that magnesium can substitute for calcium into a β-TCP structure inducing a reduction of the cell parameters and the compound crystallizes in the rhombohedral R3c structure, with the following unit cell constants: a = b = 10.3560 Å, c = 37.1718 Å, and cell volume V = 3452.44. The analysis indicated that the substitution of Mg2+ on the M(4) and M(5) sites were, approximately, 2.61 and 6.97 mol%, corresponding to the Ca2.72(MgIV0.07, MgV0.21)(PO4)2 stoichiometric formula and 0.09 Mg/(Ca+Mg) ratio.

Flexible MapReduce Workflows for Cloud Data Analytics

2013 ◽  
Vol 5 (4) ◽  
pp. 48-64 ◽  
Author(s):  
Carlos Goncalves ◽  
Luis Assuncao ◽  
Jose C. Cunha
Keyword(s):  
Text Mining ◽  
Data Analytics ◽  
Large Data ◽  
Large Data Sets ◽  
Data Sets ◽  
Tuple Space ◽  
Cloud Data ◽  
Intermediate Data ◽  
Speed Up ◽  
Mapreduce Model

Data analytics applications handle large data sets subject to multiple processing phases, some of which can execute in parallel on clusters, grids or clouds. Such applications can benefit from using MapReduce model, only requiring the end-user to define the application algorithms for input data processing and the map and reduce functions, but this poses a need to install/configure specific frameworks such as Apache Hadoop or Elastic MapReduce in Amazon Cloud. In order to provide more flexibility in defining and adjusting the application configurations, as well as in the specification of the composition of the application phases and their orchestration, the authors describe an approach for supporting MapReduce stages as sub-workflows in the AWARD framework (Autonomic Workflow Activities Reconfigurable and Dynamic). The authors discuss how a text mining application is represented as a complex workflow with multiple phases, where individual workflow nodes support MapReduce computations. Access to intermediate data produced during the MapReduce computations is supported by a data sharing abstraction. The authors describe two implementations of this abstraction, one based on a shared tuple space and another based on an in-memory distributed key/value store. The authors describe the implementation of the framework, a set of developed tools, and our experimentation with the execution of the text mining algorithm over multiple Amazon EC2 (Elastic Compute Cloud) instances, and report on the speed-up and size-up results obtained up to 20 EC2 instances and for different corpus sizes, up to 97 million words.

scholarly journals Quantitative Phase Analysis of Skarn Rocks by the Rietveld Method Using X-ray Powder Diffraction Data

Minerals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 894
Author(s):  
Yana Tzvetanova ◽  
Ognyan Petrov ◽  
Thomas Kerestedjian ◽  
Mihail Tarassov
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Rietveld Method ◽  
Rietveld Analysis ◽  
Quantitative Phase Analysis ◽  
Chemical Compositions ◽  
Powder Diffraction Data ◽  
X Ray ◽  
Fine Grained ◽  
Variable Chemical

The Rietveld method using X-ray powder diffraction data was applied to selected skarn samples for quantitative determination of the present minerals. The specimens include garnet, clinopyroxene–garnet, plagioclase–clinopyroxene–wollastonite–garnet, plagioclase–clinopyroxene–wollastonite, plagioclase–clinopyroxene–wollastonite–epidote, and plagioclase–clinopyroxene skarns. The rocks are coarse- to fine-grained and characterized by an uneven distribution of the constituent minerals. The traditional methods for quantitative analysis (point-counting and norm calculations) are not applicable for such inhomogeneous samples containing minerals with highly variable chemical compositions. Up to eight individual mineral phases have been measured in each sample. To obtain the mineral quantities in the skarn rocks preliminary optical microscopy and chemical investigation by electron probe microanalysis (EPMA) were performed for the identification of some starting components for the Rietveld analysis and to make comparison with the Rietveld X-ray powder diffraction results. All of the refinements are acceptable, as can be judged by the standard indices of agreement and by the visual fits of the observed and calculated diffraction profiles. A good correlation between the refined mineral compositions and the data of the EPMA measurements was achieved.

Rietveld Quantitative Phase Analysis of Non-Stoichiometric Cordierite Synthesised from Mainly Talc and Kaolin: Effect of Sintering Temperature

2010 ◽  
Vol 173 ◽  
pp. 190-195
Author(s):  
Johar Banjuraizah ◽  
Mohamad Hasmaliza ◽  
Zainal Arifin Ahmad
Keyword(s):  
Sintering Temperature ◽  
Raw Materials ◽  
Rietveld Method ◽  
Quantitative Phase Analysis ◽  
Secondary Phases ◽  
Grinding Media ◽  
Heat Treated ◽  
Higher Temperature ◽  
New Phase ◽  
Rietveld Quantitative Phase Analysis

Indialite or α-cordierite was synthesized by glass crystallization method using mainly talc and kaolin and with small amount of MgO, Al2O3, SiO2 to compensate the chemical formulation of non-stoihiometric compositions of cordierite. (3MgO.1.5Al2O3.5SiO2). B2O3, P2O5 and CaO was also added to decrease the melting and sintering temperature of cordierite. The glasses were pelletized and sintered from 850oC up to 1050oC. Phase compositions of both heat treated glass was quantified by X-ray powder diffraction data by the Rietveld method using TOPAS Ver 3 software. Result shows that about 60wt% of α cordierite has successfully crystallized at 850oC. Beside secondary phases (forsterite) which come from initial raw materials, phases from grinding media were also presents in the sample. The contamination was considered high since it has reacted with existence phases to form a new phase at higher temperature. Without any contamination from grinding it was expected to obtain more than 90wt% α cordierite using the same composition.

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