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1
Bigerelle, M., M. Dalla-Costa, and D. Najjar. "Multiscale similarity characterization of abraded surfaces." Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 221, no. 10 (October 1, 2007): 1473–82. http://dx.doi.org/10.1243/09544054jem770.
Анотація:
Many surface properties are related to their topography. The characteristics of an engineering surface can be recorded as a roughness profile characterized by calculation of roughness parameters. The supposed relevant parameters are used to characterize the surface and to tailor similar surfaces with the same characteristics. The aim of this paper is to propose an alternative method based on information theory to avoid roughness parameters calculation in quantifying the similarity of two roughness profiles. The relevance of this method is emphasized using experimental profiles.
2
Nigon, Benoit, Andreas Englert, Christophe Pascal, and Aline Saintot. "Multiscale Characterization of Joint Surface Roughness." Journal of Geophysical Research: Solid Earth 122, no. 12 (December 2017): 9714–28. http://dx.doi.org/10.1002/2017jb014322.
3
Bartkowiak, Tomasz, Johan Berglund, and Christopher A. Brown. "Multiscale Characterizations of Surface Anisotropies." Materials 13, no. 13 (July 7, 2020): 3028. http://dx.doi.org/10.3390/ma13133028.
Анотація:
Anisotropy can influence surface function and can be an indication of processing. These influences and indications include friction, wetting, and microwear. This article studies two methods for multiscale quantification and visualization of anisotropy. One uses multiscale curvature tensor analysis and shows anisotropy in horizontal coordinates i.e., topocentric. The other uses multiple bandpass filters (also known as sliding bandpass filters) applied prior to calculating anisotropy parameters, texture aspect ratios (Str) and texture directions (Std), showing anisotropy in horizontal directions only. Topographies were studied on two milled steel surfaces, one convex with an evident large scale, cylindrical form anisotropy, the other nominally flat with smaller scale anisotropies; a µEDMed surface, an example of an isotropic surface; and an additively manufactured surface with pillar-like features. Curvature tensors contain the two principal curvatures, i.e., maximum and minimum curvatures, which are orthogonal, and their directions, at each location. Principal directions are plotted for each calculated location on each surface, at each scale considered. Histograms in horizontal coordinates show altitude and azimuth angles of principal curvatures, elucidating dominant texture directions at each scale. Str and Std do not show vertical components, i.e., altitudes, of anisotropy. Changes of anisotropy with scale categorically failed to be detected by traditional characterization methods used conventionally. These multiscale methods show clearly in several representations that anisotropy changes with scale on actual surface measurements with markedly different anisotropies.
4
Majumdar, A., and B. Bhushan. "Role of Fractal Geometry in Roughness Characterization and Contact Mechanics of Surfaces." Journal of Tribology 112, no. 2 (April 1, 1990): 205–16. http://dx.doi.org/10.1115/1.2920243.
Анотація:
A proper characterization of the multiscale topography of rough surfaces is very crucial for understanding several tribological phenomena. Although the multiscale nature of rough surfaces warrants a scale-independent characterization, conventional techniques use scale-dependent statistical parameters such as the variances of height, slope and curvature which are shown to be functions of the surface magnification. Roughness measurements on surfaces of magnetic tape, smooth and textured magnetic thin film rigid disks, and machined stainless steel surfaces show that their spectra follow a power law behavior. Profiles of such surfaces are, therefore, statistically self-affine which implies that when repeatedly magnified, increasing details of roughness emerge and appear similar to the original profile. This paper uses fractal geometry to characterize the multiscale self-affine topography by scale-independent parameters such as the fractal dimension. These parameters are obtained from the spectra of surface profiles. It was observed that surface processing techniques which produce deterministic texture on the surface result in non-fractal structure whereas those producing random texture yield fractal surfaces. For the magnetic tape surface, statistical parameters such as the r.m.s. peak height and curvature and the mean slope, which are needed in elastic contact models, are found to be scale-dependent. The imperfect contact between two rough surfaces is composed of a large number of contact spots of different sizes. The fractal representation of surfaces shows that the size-distribution of the multiscale contact spots follows a power law and is characterized by the fractal dimension of the surface. The surface spectra and the spot size-distribution follow power laws over several decades of length scales. Therefore, the fractal approach has the potential to predict the behavior of a surface phenomenon at a particular length scale from the observations at other length scales.
5
Maleki, Iman, Marcin Wolski, Tomasz Woloszynski, Pawel Podsiadlo, and Gwidon Stachowiak. "A Comparison of Multiscale Surface Curvature Characterization Methods for Tribological Surfaces." Tribology Online 14, no. 1 (February 28, 2019): 8–17. http://dx.doi.org/10.2474/trol.14.8.
6
Chen, Chuin-Shan, Shu Kuan, Tzu-Hsuan Chang, Chia-Ching Chou, Shu-Wei Chang, and Long-Sun Huang. "Microcantilever biosensor: sensing platform, surface characterization and multiscale modeling." Smart Structures and Systems 8, no. 1 (July 25, 2011): 17–37. http://dx.doi.org/10.12989/sss.2011.8.1.017.
7
Lemesle, Julie, Frederic Robache, Gaetan Le Goic, Alamin Mansouri, Christopher A. Brown, and Maxence Bigerelle. "Surface Reflectance: An Optical Method for Multiscale Curvature Characterization of Wear on Ceramic–Metal Composites." Materials 13, no. 5 (February 25, 2020): 1024. http://dx.doi.org/10.3390/ma13051024.
Анотація:
Surface gradient characterization by light reflectance (SGCLR) is used for the first time for multiscale curvature calculations and discrimination of worn surfaces on six damaged ceramic–metal composites. Measurements are made using reflectance transformation imaging (RTI). Slope and curvature maps, generated from RTI, are analyzed instead of heights. From multiscale decompositions, bootstrapping, and analysis of variance (ANOVA), a strong correlation (R² = 0.90) is found between the density of furrows of Mehlum curvatures, with a band pass filter at 5.4 µm, present in ceramic grains and their mechanical properties. A strong correlation is found between the mean curvatures of the metal and the ceramics, with a high pass filter at 1286 µm.
8
Bartkowiak, Tomasz, Michał Mendak, Krzysztof Mrozek, and Michał Wieczorowski. "Analysis of Surface Microgeometry Created by Electric Discharge Machining." Materials 13, no. 17 (August 30, 2020): 3830. http://dx.doi.org/10.3390/ma13173830.
Анотація:
The objective of this work is to study the geometric properties of surface topographies of hot-work tool steel created by electric discharge machining (EDM) using motif and multiscale analysis. The richness of these analyses is tested through calculating the strengths of the correlations between discharge energies and resulting surface characterization parameters, focusing on the most representative surface features—craters, and how they change with scale. Surfaces were created by EDM using estimated energies from 150 to 9468 µJ and measured by focus variation microscope. The measured topographies consist of overlapping microcraters, of which the geometry was characterized using three different analysis: conventional with ISO parameters, and motif and multiscale curvature tensor analysis. Motif analysis uses watershed segmentation which allows extraction and geometrically characterization of each crater. Curvature tensor analysis focuses on the characterization of principal curvatures and their function and their evolution with scale. Strong correlations (R2 > 0.9) were observed between craters height, diameter, area and curvature using linear and logarithmic regressions. Conventional areal parameter related to heights dispersion were found to correlate stronger using logarithmic regression. Geometric characterization of process-specific topographic formations is considered to be a natural and intuitive way of analyzing the complexity of studied surfaces. The presented approach allows extraction of information directly relating to the shape and size of topographic features of interest. In the tested conditions, the surface finish is mostly affected and potentially controlled by discharge energy at larger scales which is associated with sizes of fabricated craters.
9
XIAO, Jie, Jia LI, Cristina Piluso, and Yinlun HUANG. "Multiscale Characterization of Automotive Surface Coating Formation for Sustainable Manufacturing." Chinese Journal of Chemical Engineering 16, no. 3 (June 2008): 416–23. http://dx.doi.org/10.1016/s1004-9541(08)60099-3.
10
Yang, J. J., and K. W. Xu. "Characterization of multiscale surface evolution of polycrystalline copper thin films." Journal of Applied Physics 101, no. 10 (May 15, 2007): 104902. http://dx.doi.org/10.1063/1.2732440.
11
Reggente, M., M. Natali, D. Passeri, M. Lucci, I. Davoli, G. Pourroy, P. Masson, et al. "Multiscale mechanical characterization of hybrid Ti/PMMA layered materials." Colloids and Surfaces A: Physicochemical and Engineering Aspects 532 (November 2017): 244–51. http://dx.doi.org/10.1016/j.colsurfa.2017.05.011.
12
Bartkowiak, Tomasz, Karol Grochalski, Bartosz Gapiński, and Michał Wieczorowski. "Discrimination of Surface Topographies Created by Two-Stage Process by Means of Multiscale Analysis." Materials 14, no. 22 (November 20, 2021): 7044. http://dx.doi.org/10.3390/ma14227044.
Анотація:
The fundamental issue in surface metrology is to provide methods that can allow the establishment of correlations between measured topographies and performance or processes, or that can discriminate confidently topographies that are processed or performed differently. This article presents a set of topographies from two-staged processed steel rings, measured with a 3D contact profilometer. Data were captured individually from four different regions, namely the top, bottom, inner, and outer surfaces. The rings were manufactured by drop forging and hot rolling. Final surface texture was achieved by mass finishing with spherical ceramic media or cut wire. In this study, we compared four different multiscale methods: sliding bandpass filtering, three geometric length- and area-scale analyses, and the multiscale curvature tensor approach. In the first method, ISO standard parameters were evaluated as a function of the central wavelength and bandwidth for measured textures. In the second and third method, complexity and relative length and area were utilized. In the last, multiscale curvature tensor statistics were calculated for a range of scales from the original sampling interval to its forty-five times multiplication. These characterization parameters were then utilized to determine how confident we can discriminate (through F-test) topographies between regions of the same specimen and between topographies resulting from processing with various technological parameters. Characterization methods that focus on the geometrical properties of topographic features allowed for discrimination at the finest scales only. Bandpass filtration and basic height parameters Sa and Sq proved to confidently discriminate against all factors at all three considered bandwidths.
13
Bartkowiak, Tomasz. "Novel geometric methods in multiscale analysis: curvature and slope." Mechanik 91, no. 11 (November 12, 2018): 966–69. http://dx.doi.org/10.17814/mechanik.2018.11.171.
Анотація:
The aim of this paper is to demonstrate the use of novel geometric multiscale methods in the characterization of surface topographies with a view to establishing functional relations between formation processes and resulted topography or between topography and its performance during interaction with the environment (e.g. friction, fatigue or gloss reflectance). Geometric properties of rough surfaces change with the scale of observation, i.e., measurement or calculation. In this paper, I focus on two novel method, which analyse slope and curvature in multiple scales. The digital nature of measured surfaces is recognized and is not smoothed to fit a continuous function to the measured heights. Curvature is represented as a second order tensor, which components describe maximal and minimal curvatures and their directions. In order to describe curvature distributions for analyzed regions, statistical parameters, such as: mean and standard deviation, are used. Those measures are utilized to find correlations between them and certain formation or performance parameters. The other method described here bases on slope. In this work, two calculation techniques are presented using orientation normal vectors estimated through covariance matrix method or cross product. As a result of further processing, 3D distributions of direction cosines are obtained, based on which multivariate statistical parameters are calculated (incl. measures of dispersion and higher statistical moments). This paper also presents the sample strong correlations between slope or curvature, for actual measured textures, and manufacturing or performance parameters. This indicates a great potential of those two methods in the development of multiscale characterization of surface topographies.
14
Meng, Yixue. "Analysis of surface temperature characteristics of multiscale fusion based on convolution neural network." MATEC Web of Conferences 173 (2018): 03011. http://dx.doi.org/10.1051/matecconf/201817303011.
Анотація:
Intelligent detection of surface temperature 1, describing macro characteristics of microcosmic combination, promotes the cross fusion of geoscience, thermodynamics, climatology, geological science, and so on. However, there are still two notable problems to be solved. One is the model lacks characterization capability, and the other is that the precision of surface temperature’s monitoring and prediction is low. To solve these problems, we propose an algorithm to predict surface temperature characteristics of multiscale fusion based on convolution neural network. Firstly, after researching the multiscale disturbance characteristics of surface temperature, we draw a conclusion based on analyzing time change, spatial change, casual change. To improve the parameter correlations among surface temperature characteristics, a neural network about compensating and optimizing analysis of surface temperature characteristics is proposed on the fundamental of multivariate surface temperature characterization models. By designing cluster input layer, dynamic hidden layer and visual output layer of neural network, the precise of predict data has been improved by 53.3% on average, and 76.0% on variance compared with remote sensing data. What’s more, the data consumption of this model has promoted by 17.2% in contrast to grey theory on predictive complexity and precision, and 10.8% compared with BP neural network.
15
Bartkowiak, Tomasz, and Christopher A. Brown. "Multiscale 3D Curvature Analysis of Processed Surface Textures of Aluminum Alloy 6061 T6." Materials 12, no. 2 (January 14, 2019): 257. http://dx.doi.org/10.3390/ma12020257.
Анотація:
The objectives of this paper are to demonstrate the viability, and to validate, in part, a multiscale method for calculating curvature tensors on measured surface topographies with two different methods of specifying the scale. The curvature tensors are calculated as functions of scale, i.e., size, and position from a regular, orthogonal array of measured heights. Multiscale characterization of curvature is important because, like slope and area, it changes with the scale of observation, or calculation, on irregular surfaces. Curvatures can be indicative of the topographically dependent behavior of a surface and, in turn, curvatures are influenced by the processing and use of the surface. Curvatures of surface topographies have not been well- characterized yet. Curvature has been used for calculations in contact mechanics and for the evaluation of cutting edges. Manufactured surfaces are studied for further validation of the calculation method because they provide certain expectations for curvatures, which depend on scale and the degree of curvature. To study a range of curvatures on manufactured surfaces, square edges are machined and honed, then rounded progressively by mass finishing; additionally, a set of surfaces was made by turning with different feeds. Topographic measurements are made with a scanning laser confocal microscope. The calculations use vectors, normal to the measured surface, which are calculated first, then the eigenvalue problem is solved for the curvature tensor. Plots of principal curvatures as a function of position and scale are presented. Statistical analyses show expected interactions between curvature and these manufacturing processes.
16
Mezghani, S., L. Sabri, M. El Mansori, and H. Zahouani. "On the optimal choice of wavelet function for multiscale honed surface characterization." Journal of Physics: Conference Series 311 (August 19, 2011): 012025. http://dx.doi.org/10.1088/1742-6596/311/1/012025.
17
D’Alessio, L., G. Pace, and R. Teghil. "Multiscale Analysis and Morphology of TiC Films Deposited by Pulsed Laser Ablation." Advanced Materials Research 717 (July 2013): 177–83. http://dx.doi.org/10.4028/www.scientific.net/amr.717.177.
Анотація:
In this work the microscopic morphology of titanium carbide thin films, obtained by pulsed laser ablation, are studied. A target of TiC has been ablated in vacuum with a laser Twinkle of Light Conversion Ltd. capable to furnish impulses of 250 fs, with a repetition frequency of 10 Hz at the wavelength of 527 nm. The ablated material has been deposited on (111) oriented silicon substrates, maintained at ambient temperature during the film deposition. Digital images of the films have been acquired through scanning electron microscopy. Numerical codes have been developed in Matlab environment, to obtain a three-dimensional reconstruction of the film surfaces starting from the bidimensional images. On such reconstruction a multi-scale analysis has been performed by hilbertian methods, for the characterization of the surface roughness and to study the distribution of the deposited nanoparticles. The results show that the free surface of the film has a characteristics scale invariance that allow the description by multi-fractal techniques. In particular the fractal dimension of the surface has been calculated in nanometric range. The investigation allows to identify some proper morphological indicators to characterize the film geometry and parameterize the tribological properties of the interface. These indicators, if opportunely employed together with classical methods of analysis, furnish a further tool for better understanding the complex nature of the deposits.
18
Liu, Jinping, Jiezhou He, Zhaohui Tang, Pengfei Xu, Wuxia Zhang, and Weihua Gui. "Characterization of Complex Image Spatial Structures Based on Symmetrical Weibull Distribution Model for Texture Pattern Classification." Complexity 2018 (December 2, 2018): 1–23. http://dx.doi.org/10.1155/2018/6163787.
Анотація:
Texture pattern classification has long been an essential issue in computer vision (CV). However, texture is a kind of perceptual concept of human beings in scene observation or content understanding, which cannot be defined or described clearly in CV. Visually, the visual appearance of the complex spatial structure (CSS) of texture pattern (TP) generally depends on the random organization (or layout) of local homogeneous fragments (LHFs) in the imaged surface. Hence, it is essential to investigate the latent statistical distribution (LSD) behavior of LHFs for distinctive CSS feature characterization to achieve good classification performance. This work presents an image statistical modeling-based TP identification (ISM-TPI) method. It firstly makes a theoretical explanation of the Weibull distribution (WD) behavior of the LHFs of the imaged surface in the imaging process based on the sequential fragmentation theory (SFT), which consequently derives a symmetrical WD model (SWDM) to characterize the LSD of the TP’s SS. Multidirectional and multiscale TP features are then characterized by the SWDM parameters based on the oriented differential operators; in other words, texture images are convolved with multiscale and multidirectional Gaussian derivative filters (GDFs), including the steerable isotropic GDFs (SIGDFs) and the oriented anisotropic GDFs (OAGDFs), for the omnidirectional and multiscale SS detail exhibition with low computational complexity. Finally, SWDM-based TP feature parameters, demonstrated to be directly related to the human vision perception system with significant physical perception meaning, are extracted and used to TP classification with a partial least squares-discriminant analysis- (PLS-DA-) based classifier. The effectiveness of the proposed ISM-TPI method is verified by extensive experiments on three texture image databases. The classification results demonstrate the superiority of the proposed methods over several state-of-the-art TP classification methods.
19
Gambardella, Alessandro, Gregorio Marchiori, Melania Maglio, Alessandro Russo, Chiara Rossi, Andrea Visani, and Milena Fini. "Determination of the Spatial Anisotropy of the Surface MicroStructures of Different Implant Materials: An Atomic Force Microscopy Study." Materials 14, no. 17 (August 24, 2021): 4803. http://dx.doi.org/10.3390/ma14174803.
Анотація:
Many biomaterials’ surfaces exhibit directional properties, i.e., possess spatial anisotropy on a range of spatial scales spanning from the domain of the naked eye to the sub-micrometer level. Spatial anisotropy of surface can influence the mechanical, physicochemical, and morphological characteristics of the biomaterial, thus affecting its functional behavior in relation, for example, to the host tissue response in regenerative processes, or to the efficacy of spatially organized surface patterns in avoiding bacterial attachment. Despite the importance of the availability of quantitative data, a comprehensive characterization of anisotropic topographies is generally a hard task due to the proliferation of parameters and inherent formal complications. This fact has led so far to excessive simplification that has often prevented researchers from having comparable results. In an attempt to overcome these issues, in this work a systematic and multiscale approach to spatial anisotropy is adopted, based on the determination of only two statistical parameters of surface, namely the texture aspect ratio Str and the roughness exponent H, extracted from atomic force microscopy images of the surface. The validity on this approach is tested on four commercially available implant materials, namely titanium alloy, polyethylene, polyetheretherketone and polyurethane, characterized by textured surfaces obtained after different machining. It is found that the “two parameters” approach is effective in describing the anisotropy changes on surfaces with complex morphology, providing a simple quantitative route for characterization and design of natural and artificial textured surfaces at spatial scales relevant to a wide range of bio-oriented applications.
20
Wolski, M., P. Podsiadlo, and G. W. Stachowiak. "Applications of the variance orientation transform method to the multiscale characterization of surface roughness and anisotropy." Tribology International 43, no. 11 (November 2010): 2203–15. http://dx.doi.org/10.1016/j.triboint.2010.07.006.
21
Medghalchi, Setareh, Vahid Jamebozorgi, Arjun Bala Krishnan, Smobin Vincent, Steffen Salomon, Alireza Basir Parsa, Janine Pfetzing, et al. "Multiscale Characterization of Microstructure in Near-Surface Regions of a 16MnCr5 Gear Wheel After Cyclic Loading." JOM 70, no. 9 (May 21, 2018): 1758–64. http://dx.doi.org/10.1007/s11837-018-2931-z.
22
WANG, YANG, CAIFANG WU, YANMING ZHU, SHANGBIN CHEN, SHIMIN LIU, and RUI ZHANG. "MORPHOLOGY AND FRACTAL CHARACTERIZATION OF MULTISCALE PORE STRUCTURES FOR ORGANIC-RICH LACUSTRINE SHALE RESERVOIRS." Fractals 26, no. 02 (April 2018): 1840013. http://dx.doi.org/10.1142/s0218348x18400133.
Анотація:
Lacustrine shale gas has received considerable attention and has been playing an important role in unconventional natural gas production in China. In this study, multiple techniques, including total organic carbon (TOC) analysis, X-ray diffraction (XRD) analysis, field emission scanning electron microscopy (FE-SEM), helium pycnometry and low-pressure [Formula: see text] adsorption have been applied to characterize the pore structure of lacustrine shale of Upper Triassic Yanchang Formation from the Ordos Basin. The results show that organic matter (OM) pores are the most important type dominating the pore system, while interparticle (interP) pores, intraparticle (intraP) and microfractures are also usually observed between or within different minerals. The shapes of OM pores are less complex compared with the other two pore types based on the Image-Pro Plus software analysis. In addition, the specific surface area ranges from [Formula: see text] to [Formula: see text] and the pore volume varies between [Formula: see text] and [Formula: see text]. Two fractal dimensions [Formula: see text] and [Formula: see text] were calculated using Frenkel–Halsey–Hill (FHH) method, with [Formula: see text] varying between 2.510 and 2.632, and [Formula: see text] varying between 2.617 and 2.814. Further investigation indicates that the fractal dimensions exhibit positive correlations with TOC contents, whereas there is no definite relationship observed between fractal dimensions and clay minerals. Meanwhile, the fractal dimensions increase with the increase in specific surface area, and is negatively correlated with the pore size.
23
Boventi, Matteo, Michele Mauri, and Roberto Simonutti. "129Xe: A Wide-Ranging NMR Probe for Multiscale Structures." Applied Sciences 12, no. 6 (March 19, 2022): 3152. http://dx.doi.org/10.3390/app12063152.
Анотація:
Porous materials are ubiquitous systems with a large variety of applications from catalysis to polymer science, from soil to life science, from separation to building materials. Many relevant systems of biological or synthetic origin exhibit a hierarchy, defined as spatial organization over several length scales. Their characterization is often elusive, since many techniques can only be employed to probe a single length scale, like the nanometric or the micrometric levels. Moreover, some multiscale systems lack tridimensional order, further reducing the possibilities of investigation. 129Xe nuclear magnetic resonance (NMR) provides a unique and comprehensive description of multiscale porous materials by exploiting the adsorption and diffusion of xenon atoms. NMR parameters like chemical shift, relaxation times, and diffusion coefficient allow the probing of structures from a few angstroms to microns at the same time. Xenon can evaluate the size and shape of a variety of accessible volumes such as pores, layers, and tunnels, and the chemical nature of their surface. The dynamic nature of the probe provides a simultaneous exploration of different scales, informing on complex features such as the relative accessibility of different populations of pores. In this review, the basic principles of this technique will be presented along with some selected applications, focusing on its ability to characterize multiscale materials.
24
Youssef, George, Scott Newacheck, Nha Uyen Huynh, and Carlos Gamez. "Multiscale Characterization of E-Glass/Epoxy Composite Exposed to Extreme Environmental Conditions." Journal of Composites Science 5, no. 3 (March 12, 2021): 80. http://dx.doi.org/10.3390/jcs5030080.
Анотація:
Fiber-reinforced polymer matrix composites continue to attract scientific and industrial interest since they offer superior strength-, stiffness-, and toughness-to-weight ratios. The research herein characterizes two sets of E-Glass/Epoxy composite skins: stressed and unstressed. The stressed samples were previously installed in an underground power distribution vault and were exposed to fire while the unstressed composite skins were newly fabricated and never-deployed samples. The mechanical, morphological, and elemental composition of the samples were methodically studied using a dynamic mechanical analyzer, a scanning electron microscope (SEM), and an x-ray diffractometer, respectively. Sandwich composite panels consisting of E-glass/Epoxy skin and balsa wood core were originally received, and the balsa wood was removed before any further investigations. Skin-only specimens with dimensions of ~12.5 mm wide, ~70 mm long, and ~6 mm thick were tested in a Dynamic Mechanical Analyzer in a dual-cantilever beam configuration at 5 Hz and 10 Hz from room temperature to 210 °C. Micrographic analysis using the SEM indicated a slight change in morphology due to the fire event but confirmed the effectiveness of the fire-retardant agents in quickly suppressing the fire. Accompanying Fourier transform infrared and energy dispersive X-ray spectroscopy studies corroborated the mechanical and morphological results. Finally, X-ray diffraction showed that the fire event consumed the surface level fire-retardant and the structural attributes of the E-Glass/Epoxy remained mainly intact. The results suggest the panels can continue field deployment, even after short fire incident.
25
Bilisik, Kadir, and Mahmuda Akter. "Graphene nanoplatelets/epoxy nanocomposites: A review on functionalization, characterization techniques, properties, and applications." Journal of Reinforced Plastics and Composites 41, no. 3-4 (October 7, 2021): 99–129. http://dx.doi.org/10.1177/07316844211049277.
Анотація:
Graphene nanoplatelets (GNPs) have received immense attention from the global scientific research community in the 21st century due to their two-dimensional planar structure, high surface area, functionalization abilities, and notable thermal-mechanical-electrical properties. When appropriately integrated into polymer matrices, graphene nanosheets improve the mechanical performance of polymer under static and high-strain rate loading. On the other hand, surface modification of GNPs through functionalization enhances dispersibility and interfacial strength of GNPs/polymer composites. Computational methods for GNPs-based nanocomposites considering micromechanical and multiscale modeling were also developed to predict their thermo-mechanical and electrical properties. These nanocomposite materials have been identified as having a wide range of applications in aerospace, automotive, construction, biomedical, energy storage, sensor, and textiles. In this review paper, recent advances of GNPs/epoxy nanocomposites, including their functionalization processes, characterization techniques, production methods, properties, and potential applications, have been comprehensively explained. Furthermore, it attempts to provide a complete framework for researchers by summarizing and evaluating the extensive literature on these nanocomposite materials.
26
Sanosh, Kunjalukkal Padmanabhan, Francesca Gervaso, Alessandro Sannino, and Antonio Licciulli. "Preparation and Characterization of Collagen/Hydroxyapatite Microsphere Composite Scaffold for Bone Regeneration." Key Engineering Materials 587 (November 2013): 239–44. http://dx.doi.org/10.4028/www.scientific.net/kem.587.239.
Анотація:
In the present work Collagen/Hydroxyapatite microsphere (Col/mHA) scaffold with a multiscale porosity was prepared. Col/mHA composite scaffold was prepared by freeze-drying/dehydrothermal crosslinking method. The HA microspheres (mHA) were obtained by spray drying of nanohydroxyapatite slurry prepared by precipitation technique. XRD analysis revealed that the microspheres were composed only of pure HA phase and EDS analysis revealed that Ca/P ratio was 1.69. The obtained microspheres had an average diameter 6 microns, specific surface area of 40 m2/g by BET analysis and BJH analysis shows meso porous structure having an average pore diameter 16nm. SEM analysis shows that the obtained Col/mHA scaffold had a macro porosity ranging from micron to 200 microns with meso porous mHA embedded in the collagen matrix.
27
Wen, Lei, Yaming Wang, Ying Jin, and Dongbai Sun. "Fabrication and Characterization of Multiscale Graded SMAT-MAO Composite Coating Formed on the Surface of 2024 Al Alloy." Journal of Physics: Conference Series 419 (March 28, 2013): 012031. http://dx.doi.org/10.1088/1742-6596/419/1/012031.
28
Brossier, Romain, Stéphane Operto, and Jean Virieux. "Seismic imaging of complex onshore structures by 2D elastic frequency-domain full-waveform inversion." GEOPHYSICS 74, no. 6 (November 2009): WCC105—WCC118. http://dx.doi.org/10.1190/1.3215771.
Анотація:
Quantitative imaging of the elastic properties of the subsurface at depth is essential for civil engineering applications and oil- and gas-reservoir characterization. A realistic synthetic example provides for an assessment of the potential and limits of 2D elastic full-waveform inversion (FWI) of wide-aperture seismic data for recovering high-resolution P- and S-wave velocity models of complex onshore structures. FWI of land data is challenging because of the increased nonlinearity introduced by free-surface effects such as the propagation of surface waves in the heterogeneous near-surface. Moreover, the short wavelengths of the shear wavefield require an accurate S-wave velocity starting model if low frequencies are unavailable in the data. We evaluated different multiscale strategies with the aim of mitigating the nonlinearities. Massively parallel full-waveform inversion was implemented in the frequency domain. The numerical optimization relies on a limited-memory quasi-Newton algorithm thatoutperforms the more classic preconditioned conjugate-gradient algorithm. The forward problem is based upon a discontinuous Galerkin (DG) method on triangular mesh, which allows accurate modeling of free-surface effects. Sequential inversions of increasing frequencies define the most natural level of hierarchy in multiscale imaging. In the case of land data involving surface waves, the regularization introduced by hierarchical frequency inversions is not enough for adequate convergence of the inversion. A second level of hierarchy implemented with complex-valued frequencies is necessary and provides convergence of the inversion toward acceptable P- and S-wave velocity models. Among the possible strategies for sampling frequencies in the inversion, successive inversions of slightly overlapping frequency groups is the most reliable when compared to the more standard sequential inversion of single frequencies. This suggests that simultaneous inversion of multiple frequencies is critical when considering complex wave phenomena.
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Prakasam, Mythili, Ali Chirazi, Grzegorz Pyka, Anna Prokhodtseva, Daniel Lichau, and Alain Largeteau. "Fabrication and Multiscale Structural Properties of Interconnected Porous Biomaterial for Tissue Engineering by Freeze Isostatic Pressure (FIP)." Journal of Functional Biomaterials 9, no. 3 (August 24, 2018): 51. http://dx.doi.org/10.3390/jfb9030051.
Анотація:
Biomaterial for tissue engineering is a topic of huge progress with a recent surge in fabrication and characterization advances. Biomaterials for tissue engineering applications or as scaffolds depend on various parameters such as fabrication technology, porosity, pore size, mechanical strength, and surface available for cell attachment. To serve the function of the scaffold, the porous biomaterial should have enough mechanical strength to aid in tissue engineering. With a new manufacturing technology, we have obtained high strength materials by optimizing a few processing parameters such as pressure, temperature, and dwell time, yielding the monolith with porosity in the range of 80%–93%. The three-dimensional interconnectivity of the porous media through scales for the newly manufactured biomaterial has been investigated using newly developed 3D correlative and multi-modal imaging techniques. Multiscale X-ray tomography, FIB-SEM Slice & View stacking, and high-resolution STEM-EDS electronic tomography observations have been combined allowing quantification of morphological and geometrical spatial distributions of the multiscale porous network through length scales spanning from tens of microns to less than a nanometer. The spatial distribution of the wall thickness has also been investigated and its possible relationship with pore connectivity and size distribution has been studied.
30
Lutfalla, Suzanne, Pierre Barré, Sylvain Bernard, Corentin Le Guillou, Julien Alléon, and Claire Chenu. "Multidecadal persistence of organic matter in soils: multiscale investigations down to the submicron scale." Biogeosciences 16, no. 7 (April 5, 2019): 1401–10. http://dx.doi.org/10.5194/bg-16-1401-2019.
Анотація:
Abstract. Minerals, particularly clay-sized minerals, protect soil organic matter (SOM) from decomposition by microorganisms. Here we report the characterization of SOM and the associated minerals over decades of biodegradation, in a French long-term bare fallow (LTBF) experiment started in 1928. The amounts of carbon (C) and nitrogen (N) in the study area declined over time for six fractions (sand, coarse silt, fine silt, coarse clays, intermediate clays, and fine clays). The C:N ratios of SOM associated with silt fractions remained constant, whereas the ratios significantly decreased in clays, reaching very low values in intermediate and fine clays (C:N < 5) after 8 decades of LTBF conditions. X-ray absorption spectroscopy revealed the following: (i) bulk-scale SOM chemical speciation remained almost constant; (ii) submicron particulate OM was present in coarse clays, even after 79 years of LTBF conditions; and (iii) illite particles became progressively SOM-free with time, whereas mixed-layer illite/smectite and smectites were always associated with OM throughout the bare fallow treatment. In summary, these results suggest that clay-sized minerals preferentially protect N-rich SOM and that smectites and mixed-layer illite/smectite seem to protect associated OM more effectively than pure illites.
31
Pereira, Catarina, Tito Busani, Luis C. Branco, Ineke Joosten, and Irina Crina Anca Sandu. "Nondestructive Characterization and Enzyme Cleaning of Painted Surfaces: Assessment from the Macro to Nano Level." Microscopy and Microanalysis 19, no. 6 (August 14, 2013): 1632–44. http://dx.doi.org/10.1017/s1431927613013196.
Анотація:
AbstractThis work establishes a multiscale and multitechnique nondestructive approach as valid methodology for monitoring surface properties and evaluating the effectiveness of enzymatic removal of varnishes from paintings/polychrome artefacts.Mock-up samples (documented reconstructions of oil, tempera, and gilded layers on canvas and wooden supports) were covered with different proteinaceous varnishes (egg white, animal and fish glue, casein) and then characterized before and after the removal of these coatings with enzyme-based solutions. The varnish was cleaned in several steps (two dry swabs and two wet swabs) with a clearance step for removing the residues from proteinaceous varnish or from enzyme solution.Microscopy [stereomicroscopy (SM), optical microscopy (OM), atomic force microscopy (AFM), and scanning electron microscopy (SEM)] and colorimetric (CIE L*a*b* system) techniques were used for characterization of the reconstruction surfaces at different scales (macro-scale by SM and OM; micro-scale by SEM and nano-scale by AFM). These techniques were also used to monitor the cleaning treatment.Although results presented in this work were obtained for the specific treatment of enzyme removal, the methodology could be extended to other types of materials and cleaning. Further experiments on real works of art are needed for a complete validation of the methodology.
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Kumar, R., J. L. Musuuza, A. F. Van Loon, A. J. Teuling, R. Barthel, J. Ten Broek, J. Mai, L. Samaniego, and S. Attinger. "Multiscale evaluation of the standardized precipitation index as a groundwater drought indicator." Hydrology and Earth System Sciences Discussions 12, no. 8 (August 5, 2015): 7405–36. http://dx.doi.org/10.5194/hessd-12-7405-2015.
Анотація:
Abstract. The lack of comprehensive groundwater observations at regional and global scales has promoted the use of alternative proxies and indices to quantify and predict groundwater droughts. Among them, the Standardized Precipitation Index (SPI) is commonly used to characterize droughts in different compartments of the hydro-meteorological system. In this study, we explore the suitability of the SPI to characterize local and regional scale groundwater droughts using observations at more than 2000 groundwater wells in geologically different areas in Germany and the Netherlands. A multiscale evaluation of the SPI is performed using the station data and their corresponding 0.5° gridded estimates to analyze the local and regional behavior of groundwater droughts, respectively. The standardized anomalies in the groundwater heads (SGI) were correlated against SPIs obtained using different accumulation periods. The accumulation periods to achieve maximum correlation exhibited high spatial variability (ranges 3 to 36 months) at both scales, leading to the conclusion that an a priori selection of the accumulation period (for computing the SPI) would result in inadequate characterization of groundwater droughts. The application of the uniform accumulation periods over the entire domain significantly reduced the correlation between SPI and SGI (&approx; 21–66 %) indicating the limited applicability of SPI as a proxy for groundwater droughts even at long accumulation times. Furthermore, the low scores of the hit rate (0.3–0.6) and high false alarm ratio (0.4–0.7) at the majority of the wells and grid cells demonstrated the low reliability of groundwater drought predictions using the SPI. The findings of this study highlight the pitfalls of using the SPI as a groundwater drought indicator at both local and regional scales, and stress the need for more groundwater observations and accounting for regional hydrogeological characteristics in groundwater drought monitoring.
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Bakulin, Andrey, Ilya Silvestrov, and Roman Pevzner. "Surface seismics with DAS: An emerging alternative to modern point-sensor acquisition." Leading Edge 39, no. 11 (November 2020): 808–18. http://dx.doi.org/10.1190/tle39110808.1.
Анотація:
Land seismic acquisition is moving toward “light and dense” geometries, with point receiver systems believed to be an ultimate configuration of choice. Cableless land nodal systems enable more flexible spatial sampling at the price of eliminating even small arrays. For large surveys in a desert environment, such spacing remains insufficient to address the complex near surface, while recordings with single sensors exhibit a significant reduction in data quality. At the same time, exploration problems increasingly demand smaller uncertainty in all seismic products. While 1 m geophone sampling could have addressed these problems, it remains out of economic reach as point sensor cost plateaus. We examine an emerging alternative technology of distributed acoustic sensing (DAS) that revolutionized borehole geophysics but is still mostly unknown in the seismic world. Fully broadband DAS sensors promise massive channel count and uncompromised inline sampling down to 0.25 m. Their distributed nature offers the unique capability to conduct a continuous recording with multiscale grids of “shallow,” “deep,” and “full-waveform inversion” receivers, all implemented with a single set of fixed cables and only one round of shooting. These distinct features allow us to simultaneously pursue near-surface characterization, imaging of deeper targets, and velocity model evaluation. Specifically, in a desert environment, distributed sensors may offer superior data quality compared to point sensors, whereas DAS capability of “seismic zoom” in the near surface becomes instrumental for near-surface characterization. Finally, simultaneous acquisition of surface seismic and vertical arrays that can be achieved easily with DAS can effectively address the exploration of subtler targets such as low-relief structures. We support these findings with a field case study from a desert environment and synthetic examples. With many distinct advantages, surface seismic with DAS emerges as a compelling alternative to modern point-sensor acquisitions.
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Migliazza, Maria, Maria Teresa Carriero, Andrea Lingua, Emanuele Pontoglio, and Claudio Scavia. "Rock Mass Characterization by UAV and Close-Range Photogrammetry: A Multiscale Approach Applied along the Vallone dell’Elva Road (Italy)." Geosciences 11, no. 11 (October 21, 2021): 436. http://dx.doi.org/10.3390/geosciences11110436.
Анотація:
Geostructural rock mass surveys and the collection of data related to discontinues provide the basis for the characterization of rock masses and the study of their stability conditions. This paper describes a multiscale approach that was carried out using both non-contact techniques and traditional support techniques to survey certain geometrical features of discontinuities, such as their orientation, spacing, and useful persistence. This information is useful in identifying the possible kinematics and stability conditions. These techniques are extremely useful in the case study of the Elva valley road (Northern Italy), in which instability phenomena are spread across 9 km in an overhanging rocky mass. A multiscale approach was applied, obtaining digital surface models (DSMs) at three different scales: large-scale DSM of the entire road, a medium-scale DSM to assess portions of the slope, and a small-scale DSM to assess single discontinuities. The georeferenced point cloud and consequent DSMs of the slopes were obtained using an unmanned aerial vehicle (UAV) and terrestrial photogrammetric technique, allowing topographic and rapid traditional geostructural surveys. This technique allowed us to take measurements along the entire road, obtaining geometrical data for the discontinuities that are statistically representative of the rock mass and useful in defining the possible kinematic mechanisms and volumes of potentially detachable blocks. The main purpose of this study was to analyse how the geostructural features of a rock mass can affect the stability slope conditions at different scales in order to identify road sectors susceptible to different potential failure mechanisms using only kinematic analysis.
35
Campo, L., F. Castelli, D. Entekhabi, and F. Caparrini. "Land-atmosphere interactions in an high resolution atmospheric simulation coupled with a surface data assimilation scheme." Natural Hazards and Earth System Sciences 9, no. 5 (September 30, 2009): 1613–24. http://dx.doi.org/10.5194/nhess-9-1613-2009.
Анотація:
Abstract. A valid tool for the retrieving of the turbulent fluxes that characterize the surface energy budget is constituted by the remote sensing of land surface states. In this study sequences of satellite-derived observations (from SEVIRI sensors aboard the Meteosat Second Generation) of Land Surface Temperature have been used as input in a data assimilation scheme in order to retrieve parameters that describe energy balance at the ground surface in the Tuscany region, in central Italy, during summer 2005. A parsimonious 1-D multiscale variational assimilation procedure has been followed, that requires also near surface meteorological observations. A simplified model of the surface energy balance that includes such assimilation scheme has been coupled with the limited area atmospheric model RAMS, in order to improve in the latter the accuracy of the energy budget at the surface. The coupling has been realized replacing the assimilation scheme products, in terms of surface turbulent fluxes and temperature and humidity states during the meteorological simulation. Comparisons between meteorological model results with and without coupling with the assimilation scheme are discussed, both in terms of reconstruction of surface variables and of vertical characterization of the lower atmosphere. In particular, the effects of the coupling on the moisture feedback between surface and atmosphere are considered and estimates of the precipitation recycling ratio are provided. The results of the coupling experiment showed improvements in the reconstruction of the surface states by the atmospheric model and considerable influence on the atmospheric dynamics.
36
Baboo, Joseph Paul, Shumaila Babar, Dhaval Kale, Constantina Lekakou, and Giuliano M. Laudone. "Designing a Graphene Coating-Based Supercapacitor with Lithium Ion Electrolyte: An Experimental and Computational Study via Multiscale Modeling." Nanomaterials 11, no. 11 (October 29, 2021): 2899. http://dx.doi.org/10.3390/nano11112899.
Анотація:
Graphene electrodes are investigated for electrochemical double layer capacitors (EDLCs) with lithium ion electrolyte, the focus being the effect of the pore size distribution (PSD) of electrode with respect to the solvated and desolvated electrolyte ions. Two graphene electrode coatings are examined: a low specific surface area (SSA) xGNP-750 coating and a high SSA coating based on a-MWGO (activated microwave expanded graphene oxide). The study comprises an experimental and a computer modeling part. The experimental part includes fabrication, material characterization and electrochemical testing of an EDLC with xGNP-750 coating electrodes and electrolyte 1M LiPF6 in EC:DMC. The computational part includes simulations of the galvanostatic charge-discharge of each EDLC type, based on a continuum ion transport model taking into account the PSD of electrodes, as well as molecular modeling to determine the parameters of the solvated and desolvated electrolyte ions and their adsorption energies with each type of electrode pore surface material. Predictions, in agreement with the experimental data, yield a specific electrode capacitance of 110 F g−1 for xGNP-750 coating electrodes in electrolyte 1M LiPF6 in EC:DMC, which is three times higher than that of the high SSA a-MWGO coating electrodes in the same lithium ion electrolyte.
37
Kruk, Adam, Aleksander Gil, Sebastian Lech, Grzegorz Cempura, Alina Agüero, and Aleksandra Czyrska-Filemonowicz. "Multiscale Characterization of an Oxide Scale Formed on the Creep-Resistant ATI 718Plus Superalloy during High-Temperature Oxidation." Materials 14, no. 21 (October 23, 2021): 6327. http://dx.doi.org/10.3390/ma14216327.
Анотація:
The ATI 718Plus® is a creep-resistant nickel-based superalloy exhibiting high strength and excellent oxidation resistance in high temperatures. The present study is focused on multiscale 2D and 3D characterization (morphological and chemical) of the scale and the layer beneath formed on the ATI 718Plus superalloy during oxidation at 850 °C up to 4000 h in dry and wet air. The oxidized samples were characterized using various microscopic methods (SEM, TEM and STEM), energy-dispersive X-ray spectroscopy and electron diffraction. The 3D visualization of the microstructural features was achieved by means of FIB-SEM tomography. When oxidized in dry air, the ATI 718Plus develops a protective, dense Cr2O3 scale with a dual-layered structure. The outer Cr2O3 layer is composed of coarser grains with a columnar shape, while the inner one features fine, equiaxed grains. The Cr2O3 scale formed in wet air is single-layered and features very fine grains. The article discusses the difference between the structure, chemistry and three-dimensional phase distribution of the oxide scales and near-surface areas developed in the two environments. Electron microscopy/spectroscopy findings combined with the three-dimensional reconstruction of the microstructure provide original insight into the role of the oxidation environment on the structure of the ATI 718Plus at the nanoscale.
38
Thompson, Karsten E., Clinton S. Willson, Christopher D. White, Stephanie Nyman, Janok P. Bhattacharya, and Allen H. Reed. "Application of a New Grain-Based Reconstruction Algorithm to Microtomography Images for Quantitative Characterization and Flow Modeling." SPE Journal 13, no. 02 (June 1, 2008): 164–76. http://dx.doi.org/10.2118/95887-pa.
Анотація:
Summary X-ray computed microtomography (XMT) is used for high-resolution, nondestructive imaging and has been applied successfully to geologic media. Despite the potential of XMT to aid in formation evaluation, currently it is used mostly as a research tool. One factor preventing more widespread application of XMT technology is limited accessibility to microtomography beamlines. Another factor is that computational tools for quantitative image analysis have not kept pace with the imaging technology itself. In this paper, we present a new grain-based algorithm used for network generation. The algorithm differs from other approaches because it uses the granular structure of the material as a template for creating the pore network rather than operating on the voxel set directly. With this algorithm, several advantages emerge: the algorithm is significantly faster computationally, less dependent on image resolution, and the network structure is tied to the fundamental granular structure of the material. In this paper, we present extensive validation of the algorithm using computer-generated packings. These analyses provide guidance on issues such as accuracy and voxel resolution. The algorithm is applied to two sandstone samples taken from different facies of the Frontier Formation in Wyoming, USA, and imaged using synchrotron XMT. Morphologic and flow-modeling results are presented. Introduction Subsurface transport processes such as oil and gas production are multiscale processes. The pore scale governs many physical and chemical interactions and is the appropriate characteristic scale for the fundamental governing equations. The continuum scale is used for most core or laboratory scale measurements (e.g., Darcy velocity, phase saturation, and bulk capillary pressure). The field scale is the relevant scale for production and reservoir simulation. Multiscale modeling strategies aim to address these complexities by integrating the various length scales. While pore-scale modeling is an essential component of multiscale modeling, quantitative methods are not as well-developed as their continuum-scale counterparts. Hence, pore-scale modeling represents a weak link in current multiscale techniques. The most fundamental approach for pore-scale modeling is direct solution of the equations of motion (along with other relevant conservation equations), which can be performed using a number of numerical techniques. The finite-element method is the most general approach in terms of the range of fluid and solid mechanics problems that can be addressed. Finite-difference and finite-volume methods are more widely used in the computational fluid dynamics community. The boundary element method is very well suited for low-Reynolds number flow of Newtonian fluids (including multiphase flows). Finally, the lattice-Boltzmann method has been favored in the porous-media community because it easily adapts to the complex geometries found in natural materials. A less rigorous approach is network modeling, which gives an approximate solution to the governing equations. It requires discretization of the pore space into pores and pore throats, and transport is modeled by imposing conservation equations at the pore scale. Network modeling involves two levels of approximation. The first is the representation of the complex, continuous void space as discrete pores and throats. The second is the approximation to the fluid mechanics when solving the governing equations within the networks. The positive tradeoff for these significant simplifications is the ability to model transport over orders-of-magnitude larger characteristic scales than is possible with direct solutions of the equations of motion. Consequently, the two approaches (rigorous modeling of the conservation equations vs. network modeling) have complementary roles in the overall context of multiscale modeling. Direct methods will remain essential for studying first-principles behavior and subpore-scale processes such as diffusion boundary layers during surface reactions, while network modeling will provide the best avenue for capturing larger characteristic scales (which is necessary for modeling the pore-to-continuum-scale transition). This research addresses one of the significant hurdles for quantitative network modeling: the use of high-resolution imaging of real materials for quantitative flow modeling. We focus in particular on XMT to obtain 3D pore-scale images, and present a new technique for direct mapping of the XMT data onto networks for quantitative modeling. This direct mapping (in contrast to the generation of statistically equivalent networks) ensures that subtle spatial correlations present in the original material are retained in the network structure.
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Rébiscoul, Diane, Emilien Burger, Florence Bruguier, Nicole Godon, Jean-Louis Chouchan, Jean-Pierre Mestre, Pierre Frugier, Jean-Eric Lartigue, and Stephane Gin. "Glass-Iron-Clay interactions in a radioactive waste geological disposal: a multiscale approach." MRS Proceedings 1518 (2013): 185–90. http://dx.doi.org/10.1557/opl.2013.67.
Анотація:
ABSTRACTIn France, nuclear glass canisters arising from spent fuel reprocessing are expected to be disposed in a deep geological repository using a multi-barrier concept (glass/canister/steel overpack and claystone). In this context, glass - iron or corrosion products interactions were investigated in a clayey environment to better understand the mechanisms and driving forces controlling the glass alteration. Integrated experiments involving glass - metallic iron or magnetite - clay stacks were run at laboratory scale in anoxic conditions for two years. The interfaces were characterized by a multiscale approach using SEM, TEM, EDX and STXM at the SLS Synchrotron. Characterization of glass alteration patterns on cross sections revealed various morphologies or microstructures and an increase of the glass alteration with the proximity between the glass and the source of iron (metallic iron or magnetite) due to the consumption of the silica coming from the glass alteration. In case of magnetite, the silica consumption is mainly driven by a sorption of silica onto the magnetite. For experiments containing metallic iron, the silica consumption seems to be strongly driven by silicates precipitation including Fe and Fe/Mg when the Fe is not enough available. Moreover, in addition to Fe-silicates observed at the surface of the gel layers, iron is incorporated within the gel probably as nanosized precipitates of Fe-silicates which could affect its physical and chemical properties. Those results highlighted the impact of the distance between glass and iron source and the nature of the iron source which drive the process consuming the silica coming from the glass alteration.
40
Merson, Evgeniy, Pavel Myagkikh, Vitaliy Poluyanov, Maxim Dorogov, Dmitri Merson, and Alexei Vinogradov. "The fundamental difference between cleavage and hydrogen-assisted quasi-cleavage in ferritic materials revealed by multiscale quantitative fractographic and side surface characterization." Materials Science and Engineering: A 824 (September 2021): 141826. http://dx.doi.org/10.1016/j.msea.2021.141826.
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Itahashi, Syuichi, Rohit Mathur, Christian Hogrefe, and Yang Zhang. "Modeling stratospheric intrusion and trans-Pacific transport on tropospheric ozone using hemispheric CMAQ during April 2010 – Part 1: Model evaluation and air mass characterization for stratosphere–troposphere transport." Atmospheric Chemistry and Physics 20, no. 6 (March 23, 2020): 3373–96. http://dx.doi.org/10.5194/acp-20-3373-2020.
Анотація:
Abstract. Stratospheric intrusion and trans-Pacific transport have been recognized as a potential source of tropospheric ozone over the US. The state-of-the-science Community Multiscale Air Quality (CMAQ) modeling system has recently been extended for hemispheric-scale modeling applications (referred to as H-CMAQ). In this study, H-CMAQ is applied to study the stratospheric intrusion and trans-Pacific transport during April 2010. The results will be presented in two companion papers. In this Part 1 paper, model evaluation for tropospheric ozone (O3) is presented. Observations at the surface, by ozonesondes and airplane, and by satellite across the Northern Hemisphere are used to evaluate the model performance for O3. H-CMAQ is able to capture surface and boundary layer (defined as surface to 750 hPa) O3 with a normalized mean bias (NMB) of −10 %; however, a systematic underestimation with an NMB up to −30 % is found in the free troposphere (defined as 750–250 hPa). In addition, a new air mass characterization method is developed to distinguish influences of stratosphere–troposphere transport (STT) from the effects of photochemistry on O3 levels. This method is developed based on the ratio of O3 and an inert tracer indicating stratospheric O3 to examine the importance of photochemistry, and sequential intrusion from upper layer. During April 2010, on a monthly average basis, the relationship between surface O3 mixing ratios and estimated stratospheric air masses in the troposphere show a slight negative slope, indicating that high surface O3 values are primarily affected by other factors (i.e., emissions), whereas this relationship shows a slight positive slope at elevated sites, indicating that STT has a possible impact at elevated sites. STT shows large day-to-day variations, and STT impacts can either originate from the same air mass over the entire US with an eastward movement found during early April, or stem from different air masses at different locations indicated during late April. Based on this newly established air mass characterization technique, this study can contribute to understanding the role of STT and also the implied importance of emissions leading to high surface O3. Further research focused on emissions is discussed in a subsequent paper (Part 2).
42
Mo, Pin-Qiang. "Internal rolling method for particle shape evaluation and reconstruction." PLOS ONE 15, no. 11 (November 12, 2020): e0242162. http://dx.doi.org/10.1371/journal.pone.0242162.
Анотація:
A concise and robust method for 2D particle shape evaluation and reconstruction is proposed using the concept of the internal rolling of covering discs within the outline of a particle. By downscaling the covering disc size for capturing multiscale features, the calculation of the Euclidean distance can effectively yield three indices for sphericity, roundness and roughness. The geometric-based evaluations of particle morphology are dimensionless and precisely distinguishable between shapes after calibration and validation against constructed particles and natural sands. A sphericity-roundness diagram is provided to visualize the particle shape characterization, and a probabilistic density surface in the sphericity-roundness diagram is then proposed to statistically represent the distributions of the particle shapes. The concept of internal rolling is also utilized for particle shape reconstruction using a limited number of balls to replicate the indices of sphericity, roundness and roundness characteristic curve. The probabilistic density surface is duplicated for statistical particle shape reconstruction, which provides an effective approach for numerical investigations of the relationships between particle shapes and mechanical behavior. The effect of image quality on 2D shape evaluation is also examined by using a minimum area per particle, and the proposed method is intuitively extendable to 3D measurements using rolling covering spheres.
43
Otte, Tanya L. "The Impact of Nudging in the Meteorological Model for Retrospective Air Quality Simulations. Part II: Evaluating Collocated Meteorological and Air Quality Observations." Journal of Applied Meteorology and Climatology 47, no. 7 (July 1, 2008): 1868–87. http://dx.doi.org/10.1175/2007jamc1791.1.
Анотація:
Abstract For air quality modeling, it is important that the meteorological fields that are derived from meteorological models reflect the best characterization of the atmosphere. It is well known that the accuracy and overall representation of the modeled meteorological fields can be improved for retrospective simulations by creating dynamic analyses in which Newtonian relaxation, or “nudging,” is used throughout the simulation period. This article, the second of two parts, provides additional insight into the value of using nudging-based data assimilation for dynamic analysis in the meteorological fields for air quality modeling. Meteorological simulations are generated by the fifth-generation Pennsylvania State University–National Center for Atmospheric Research Mesoscale Model (MM5) using both the traditional dynamic analysis approach and forecasts for a summertime period. The resultant meteorological fields are then used for emissions processing and air quality simulations using the Community Multiscale Air Quality Modeling System (CMAQ). The predictions of surface and near-surface meteorological fields and ozone are compared with a small network of collocated meteorological and air quality observations. Comparisons of 2-m temperature, 10-m wind speed, and surface shortwave radiation show a significant degradation over time when nudging is not used, whereas the dynamic analyses maintain consistent statistical scores over time for those fields. Using nudging in MM5 to generate dynamic analyses, on average, leads to a CMAQ simulation of hourly ozone with smaller error. Domainwide error patterns in specific meteorological fields do not directly or systematically translate into error patterns in ozone prediction at these sites, regardless of whether nudging is used in MM5, but large broad-scale errors in shortwave radiation prediction by MM5 directly affect ozone prediction by CMAQ at specific sites.
44
Zhang, Yichi, Yangyao Ding, and Panagiotis D. Christofides. "Integrating Feedback Control and Run-to-Run Control in Multi-Wafer Thermal Atomic Layer Deposition of Thin Films." Processes 8, no. 1 (December 21, 2019): 18. http://dx.doi.org/10.3390/pr8010018.
Анотація:
There is currently a lack of understanding of the deposition profile in a batch atomic layer deposition (ALD) process. Also, no on-line control scheme has been proposed to resolve the prevalent disturbances. Motivated by this, we develop a computational fluid dynamics (CFD) model and an integrated online run-to-run and feedback control scheme. Specifically, we analyze a furnace reactor for a SiO2 thin-film ALD with BTBAS and ozone as precursors. Initially, a high-fidelity 2D axisymmetric multiscale CFD model is developed using ANSYS Fluent for the gas-phase characterization and the surface thin-film deposition, based on a kinetic Monte-Carlo (kMC) model database. To deal with the disturbance during reactor operation, a proportional integral (PI) control scheme is adopted, which manipulates the inlet precursor concentration to drive the precursor partial pressure to the set-point, ensuring the complete substrate coverage. Additionally, the CFD model is utilized to investigate a wide range of operating conditions, and a regression model is developed to describe the relationship between the half-cycle time and the feed flow rate. A run-to-run (R2R) control scheme using an exponentially weighted moving average (EWMA) strategy is developed to regulate the half-cycle time for the furnace ALD process between batches.
45
Shenoy, Samantha, Keilyn Ing, Richard P. Barber, Edward C. Rooks, and Janice S. Edgerly. "A Multiscale Characterization of Two Tropical Embiopteran Species: Nano- and Microscale Features of Silk, Silk-Spinning Behavior, and Environmental Correlates of their Distributions." Environmental Entomology 49, no. 5 (July 22, 2020): 1242–51. http://dx.doi.org/10.1093/ee/nvaa073.
Анотація:
Abstract Embioptera display the unique ability to spin silk with their front feet to create protective domiciles. Their body form is remarkably uniform throughout the order, perhaps because they all live within the tight confines of silken tubes. This study contributes to an understanding of the ecology of Embioptera, an order that is rarely studied in the field. We conducted a census to quantify the habitats of two species with overlapping distributions on the tropical island of Trinidad in a search for characteristics that might explain their distinct ecologies. One species, Antipaluria urichi (Saussure) (Embioptera: Clothodidae), lives in larger colonies with more expansive silk in habitats throughout the island, especially in the rainforest of the Northern Range Mountains. The other, Pararhagadochir trinitatis (Saussure) (Embioptera: Scelembiidae), was found only in lowland locations. We quantified silk-spinning behavior and productivity of the two species and found that A. urichi spins thicker silk sheets per individual and emphasizes spin-steps that function to create a domicile that is more expansive than that produced by P. trinitatis. Their silks also interact differently when exposed to water: the smaller-diameter silk fibers of P. trinitatis form more continuous films on the surface of the domicile after being wetted and dried than that seen in A. urichi silk. This tendency gives P. trinitatis silk a shiny appearance in the field compared to the more cloth-like silk of A. urichi. How these silks function in the field and if the differences are partially responsible for the distinct distributions of the two species remain to be determined.
46
Otte, Tanya L. "The Impact of Nudging in the Meteorological Model for Retrospective Air Quality Simulations. Part I: Evaluation against National Observation Networks." Journal of Applied Meteorology and Climatology 47, no. 7 (July 1, 2008): 1853–67. http://dx.doi.org/10.1175/2007jamc1790.1.
Анотація:
Abstract It is common practice to use Newtonian relaxation, or nudging, throughout meteorological model simulations to create “dynamic analyses” that provide the characterization of the meteorological conditions for retrospective air quality model simulations. Given the impact that meteorological conditions have on air quality simulations, it has been assumed that the resultant air quality simulations would be more skillful by using dynamic analyses rather than meteorological forecasts to characterize the meteorological conditions, and that the statistical trends in the meteorological model fields are also reflected in the air quality model. This article, which is the first of two parts, demonstrates the impact of nudging in the meteorological model on retrospective air quality model simulations. Here, meteorological simulations are generated by the fifth-generation Pennsylvania State University–National Center for Atmospheric Research Mesoscale Model (MM5) using both the traditional dynamic analysis approach and using forecasts for a summertime period. The resultant fields are then used to characterize the meteorological conditions for emissions processing and air quality simulations using the Community Multiscale Air Quality (CMAQ) Modeling System. As expected, on average, the near-surface meteorological fields show a significant degradation over time in the forecasts (when nudging is not used), while the dynamic analyses maintain nearly constant statistical scores in time. The use of nudged MM5 fields in CMAQ generally results in better skill scores for daily maximum 1-h ozone mixing ratio simulations. On average, the skill of the daily maximum 1-h ozone simulation deteriorates significantly over time when nonnudged MM5 fields are used in CMAQ. The daily maximum 1-h ozone mixing ratio also degrades over time in the CMAQ simulation that uses MM5 dynamic analyses, although to a much lesser degree, despite no aggregate loss of skill over time in the dynamic analyses themselves. These results affirm the advantage of using nudging in MM5 to create the meteorological characterization for CMAQ for retrospective simulations, and it is shown that MM5-based dynamic analyses are robust at the surface throughout 5.5-day simulations.
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Nawroth, Janna C., Hanliang Guo, Eric Koch, Elizabeth A. C. Heath-Heckman, John C. Hermanson, Edward G. Ruby, John O. Dabiri, Eva Kanso, and Margaret McFall-Ngai. "Motile cilia create fluid-mechanical microhabitats for the active recruitment of the host microbiome." Proceedings of the National Academy of Sciences 114, no. 36 (August 23, 2017): 9510–16. http://dx.doi.org/10.1073/pnas.1706926114.
Анотація:
We show that mucociliary membranes of animal epithelia can create fluid-mechanical microenvironments for the active recruitment of the specific microbiome of the host. In terrestrial vertebrates, these tissues are typically colonized by complex consortia and are inaccessible to observation. Such tissues can be directly examined in aquatic animals, providing valuable opportunities for the analysis of mucociliary activity in relation to bacteria recruitment. Using the squid–vibrio model system, we provide a characterization of the initial engagement of microbial symbionts along ciliated tissues. Specifically, we developed an empirical and theoretical framework to conduct a census of ciliated cell types, create structural maps, and resolve the spatiotemporal flow dynamics. Our multiscale analyses revealed two distinct, highly organized populations of cilia on the host tissues. An array of long cilia (∼25 μm) with metachronal beat creates a flow that focuses bacteria-sized particles, at the exclusion of larger particles, into sheltered zones; there, a field of randomly beating short cilia (∼10 μm) mixes the local fluid environment, which contains host biochemical signals known to prime symbionts for colonization. This cilia-mediated process represents a previously unrecognized mechanism for symbiont recruitment. Each mucociliary surface that recruits a microbiome such as the case described here is likely to have system-specific features. However, all mucociliary surfaces are subject to the same physical and biological constraints that are imposed by the fluid environment and the evolutionary conserved structure of cilia. As such, our study promises to provide insight into universal mechanisms that drive the recruitment of symbiotic partners.
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Singh, Sagar, Ilya Tsvankin, and Ehsan Zabihi Naeini. "Full-waveform inversion with borehole constraints for elastic VTI media." GEOPHYSICS 85, no. 6 (November 1, 2020): R553—R563. http://dx.doi.org/10.1190/geo2019-0816.1.
Анотація:
The nonlinearity of full-waveform inversion (FWI) and parameter trade-offs can prevent convergence toward the actual model, especially for elastic anisotropic media. The problems with parameter updating become particularly severe if ultra-low-frequency seismic data are unavailable, and the initial model is not sufficiently accurate. We introduce a robust way to constrain the inversion workflow using borehole information obtained from well logs. These constraints are included in the form of rock-physics relationships for different geologic facies (e.g., shale, sand, salt, and limestone). We develop a multiscale FWI algorithm for transversely isotropic media with a vertical symmetry axis (VTI media) that incorporates facies information through a regularization term in the objective function. That term is updated during the inversion by using the models obtained at the previous inversion stage. To account for lateral heterogeneity between sparse borehole locations, we use an image-guided smoothing algorithm. Numerical testing for structurally complex anisotropic media demonstrates that the facies-based constraints may ensure the convergence of the objective function towards the global minimum in the absence of ultra-low-frequency data and for simple (even 1D) initial models. We test the algorithm on clean data and on surface records contaminated by Gaussian noise. The algorithm also produces a high-resolution facies model, which should be instrumental in reservoir characterization.
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SONG, WENHUI, JUN YAO, YANG LI, HAI SUN, DONGYING WANG, and XIA YAN. "GAS–WATER RELATIVE PERMEABILITIES FRACTAL MODEL IN DUAL-WETTABILITY MULTISCALE SHALE POROUS MEDIA DURING INJECTED WATER SPONTANEOUS IMBIBITION AND FLOW BACK PROCESS." Fractals 28, no. 07 (November 2020): 2050103. http://dx.doi.org/10.1142/s0218348x20501030.
Анотація:
The multiphase flow behavior in shale porous media is known to be affected by multiscale pore size, dual surface wettability, and nanoscale transport mechanisms. However, it has not been fully understood so far. In this study, fractal model of gas–water relative permeabilities (RP) in dual-wettability shale porous media for both injected water spontaneous imbibition and the flow back process are proposed using fractal geometry. The shale pore structure is described as tortuous with different pore sizes and morphologies including slit pore, equilateral triangle, circular pore and square pore. The proportion of each pore morphology can be obtained from SEM/FIB-SEM pore structure characterization results. Injected water spontaneous imbibition after hydraulic fracturing is modeled as the capillary force dominated process and injected water flow back is modeled as a non-wetting gas phase drainage process in inorganic matter. The organic pores are deemed to be not accessible by injected water. The boundary slip of water and free gas flow in the inorganic matrix are considered while both free gas flow and adsorbed gas flow are modeled in organic matter. The proposed gas–water RP fractal model is verified via comparisons with the available experimental data and is discussed in detail. Study results reveal that gas phase RP increases with increasing pore fractal dimensions and tortuosity fractal dimensions, whereas it decreases with increasing Total Organic Carbon (TOC) volumes. Water phase RP decreases with increasing of pore fractal dimensions and tortuosity fractal dimensions, whereas it increases with increasing TOC volumes.
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Saulquin, Bertrand, Ronan Fablet, Gregoire Mercier, Herve Demarcq, Antoine Mangin, and Odile Hembise Fanton d'Andon. "Multiscale Event-Based Mining in Geophysical Time Series: Characterization and Distribution of Significant Time-Scales in the Sea Surface Temperature Anomalies Relatively to ENSO Periods from 1985 to 2009." IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing 7, no. 8 (August 2014): 3543–52. http://dx.doi.org/10.1109/jstars.2014.2329921.