scholarly journals Quantification Analysis of Geometric Characteristics of Micro Crack Network On Fault Rock Surface

2022 ◽  
Author(s):  
Haitao Yu ◽  
Zhibin Liu ◽  
Yun Zhang ◽  
Tingyi Luo ◽  
Yasen Tang
Keyword(s):  
Geometric Characteristic ◽  
Crack Density ◽  
Polarized Light ◽  
Sample Surface ◽  
Rock Surface ◽  
Sem Images ◽  
Fault Rock ◽  
Crack Network ◽  
Geometric Characteristics ◽  
Rock Samples

Abstract Fault is a common water conduit in coal mine, and the cracks of fault rock will greatly affect its permeability. In this study, three fault samples obtained in the mining area in Southwest Shandong of China was tested and observed by SEM, XRD and plane-polarized light microscope. The geometric characteristics, including crack density, fractal dimension and crack connectivity, of the crack network on the sample surface were calculated. Combined with the mineral content obtained by XRD, the nonuniformity coefficient of mineral composition in rock is defined. The results show that the crack geometric characteristics of the three samples are quite different and the above geometric parameters of crack network on three fault rock samples are correlated. The optical photomicrographs and SEM images show that the crack network is developed most in the fault rock samples with the least clay content. The study suggests that the nonuniformity coefficient of rock samples is positively correlated with the geometric characteristic of crack network. The difference in the crack network of fault rock samples is related to the coefficient of friction of clay.

scholarly journals Influence of pretreatment on the properties of α-Fe2O3 and the effect on photocatalytic degradation of methylene blue under visible light

2020 ◽  
Vol 82 (11) ◽  
pp. 2415-2424
Author(s):  
S. Mokhtari ◽  
N. Dokhan ◽  
S. Omeiri ◽  
B. Berkane ◽  
M. Trari
Keyword(s):  
Methylene Blue ◽  
Average Crystallite Size ◽  
Sample Surface ◽  
X Ray Diffraction ◽  
Sem Images ◽  
X Ray ◽  
Lattice Constants ◽  
Electrochemical Pretreatment ◽  
Crystal Properties ◽  
Rhombohedral Symmetry

Abstract The hematite (α-Fe2O3) nanostructures were synthesized by thermal oxidation of metal at 500 °C under atmospheric pressure. We studied the effect of the electrochemical pretreatment of the substrate before calcinations and its impact on the morphology, crystalline structure, lattice microstructural, and optical properties of α-Fe2O3. Uniform nanosheets were observed on the sample surface after calcination; their dimension and morphology were accentuated by the pretreatment, as confirmed by the SEM images. The characteristics of the nanostructures, analyzed by X-ray diffraction (XRD), revealed a rhombohedral symmetry with the space group R-3c and lattice constants: a = 0.5034 nm and c = 1.375 nm. The average crystallite size and strain, determined from the Williamson-Hall (W-H) plot, showed substantial variations after the substrate pretreatment. The Raman spectroscopy confirmed the changes in the crystal properties of the hematite submitted to pretreatment. The diffuse reflectance allowed to evaluate the optical gap which lies between 1.2 and 1.97 eV, induced by the electrochemical processing. The photocatalytic activity of α-Fe2O3 films was assessed by the degradation of methylene blue (MB) under LED light; 15% enhancement of the degradation for the pretreated specimens was noticed.

The role of freezing-thaw cycling in rock samples topography evolution and rock cliff retreat

2021 ◽  
Author(s):  
Li Fei ◽  
Marc-Henri Derron ◽  
Tiggi Choanji ◽  
Michel Jaboyedoff ◽  
Chunwei Sun ◽  
...  
Keyword(s):  
Freezing Point ◽  
Meteorological Data ◽  
Test Chamber ◽  
Monitoring Program ◽  
Dynamic Environment ◽  
Rock Properties ◽  
Rock Surface ◽  
Physical Weathering ◽  
Rock Samples

<p>Freezing-thaw weathering is recognized as one of the most significant factors in the fatigue of rock mass in areas where the temperature periodically fluctuates around the freezing point. <br>A one-year monthly SfM monitoring program from December 19, 2019, to January 7, 2021, was done to detect rockfall activity on a rockslide cliff composed of marl-sandstone at La Cornalle, Switzerland. More than one hundred rockfall events were detected during this period with the volumes varied from 0.005m<sup>3</sup> to 4.85m<sup>3</sup>. <br>We texture all the rockfalls on the 3D SfM model. It is shown that most of them are mainly located in three areas:  the top of the cliff, the foot of the cliff, and the medium-left part of the cliff. The common feature of these three parts is that the layers are more or less overhanging with dense fractures around them. At the same time, the meteorological data collected by a weather station on site is correlated with the rockfall events to figure out the relationship between each other. Actually, about 30% of total rockfall volume fell during winter on this site. The triggering factor of rockfall during winter is related to freezing-thaw cycling. This kind of weathering can be understood as an interplay between rock properties and its dynamic environment.<br>In order to make clear the role of freezing-thaw played on the rockfall generation, an on-site 24h monitoring measurement program that consists of two crack meters, one rock thermal sensor, and thermal camera monitoring is installed in January 2021. Those datasets will help to understand how the crack grows with the changing temperature. In addition, freezing-thaw cycling laboratory experiments for the rock samples taken from different areas of the cliff will be done with an environmental test chamber. The topography of the rock samples before and after the experiments will be acquired by a 3D handheld scanner. This work will benefit to reveal the rock surface evolution during the freezing-thaw cycling in a dynamic environment with varied humidity and number of cycles. <br>In conclusion, the combination of on-site measurements and laboratory freezing-thaw experiments will provide a good basis for a better understanding of the rockfall triggering mechanism led by physical weathering.</p>

scholarly journals Performance of Laser Fluorescence for Residual Caries Detection in Primary Teeth

2008 ◽  
Vol 02 (03) ◽  
pp. 176-184 ◽  
Author(s):  
Taskin Gurbuz ◽  
Yucel Yilmaz ◽  
Fatih Sengul
Keyword(s):  
Light Microscopy ◽  
Gold Standard ◽  
Primary Teeth ◽  
Polarized Light ◽  
Laser Fluorescence ◽  
Caries Detection ◽  
Sem Images ◽  
Significant Difference ◽  
Residual Caries ◽  
Cavity Floor

ABSTRACTObjectives: The aim of this study was to evaluate the performance of a visual-tactile examination and a laser fluorescence device for detecting residual dentinal caries after carious dentin removal with bur excavation, hand excavation and chemomechanical excavation (Carisolv™].Methods: Thirty extracted coronal caries primary second molars were used. The caries infected dentin has been removed. A blinded examiner checked all cavities for residual caries using a visualtactile examination and laser fluorescence. Then the teeth were sectioned through the prepared cavities andthe two halves of each tooth were processed for light microscopy and Scanning Electron Microscopy (SEM). The presence or absence of residual caries was verified using polarized light microscopy as the gold standard. The cavity floor dentin after removing carious dentin was examined using SEM.Results: In among all groups a significant difference is determined between visual-tactile examination and laser fluorescence (P<.05). There was an agreement between laser fluorescence or visual-tactile examination and histological gold standard (P>.05). In addition, SEM images of the surfaces with the caries removed have shown that a vast majority of the tubule openings is observed to be open in the samples of the Carisolv group in opposition to the other groups.Conclusions: The laser fluorescence system could be effective in checking the removal by other methods, such as bur or Carisolv and avoid excessive removal of the sound dentin. (Eur J Dent 2008;2:176-184)

scholarly journals Effect of Precursor Concentration on Structural Optical and Electrical Properties of NiO Thin Films Prepared by Spray Pyrolysis

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Rafia Barir ◽  
Boubaker Benhaoua ◽  
Soufiane Benhamida ◽  
Achour Rahal ◽  
Toufik Sahraoui ◽  
...  
Keyword(s):  
Thin Films ◽  
Electrical Properties ◽  
Spray Pyrolysis ◽  
Sample Surface ◽  
Precursor Concentration ◽  
Spray Pyrolysis Method ◽  
Nitrate Hexahydrate ◽  
Optical And Electrical Properties ◽  
Sem Images ◽  
Nano Structure

Undoped nickel oxide (NiO) thin films were deposited on 500°C heated glass substrates using spray pyrolysis method at (0.015–0.1 M) range of precursor. The latter was obtained by decomposition of nickel nitrate hexahydrate in double distilled water. Effect of precursor concentration on structural, optical, and electrical properties of NiO thin films was investigated. X-ray diffraction (XRD) shows the formation of NiO under cubic structure with single diffraction peak along (111) plane at 2θ=37.24°. When precursor concentration reaches 0.1 M, an increment in NiO crystallite size over 37.04 nm was obtained indicating the product nano structure. SEM images reveal that beyond 0.04 M as precursor concentration the substrate becomes completely covered with NiO and thin films exhibit formation of nano agglomerations at the top of the sample surface. Ni-O bonds vibrations modes in the product of films were confirmed by FT-IR analysis. Transparency of the films ranged from 57 to 88% and band gap energy of the films decreases from 3.68 to 3.60 eV with increasing precursor concentration. Electrical properties of the elaborated NiO thin films were correlated to the precursor concentration.

scholarly journals Evaluating Geometric Characteristics of Planar Surfaces using Improved Particle Swarm Optimization

2017 ◽  
Vol 17 (4) ◽  
pp. 187-196 ◽  
Author(s):  
Vimal Kumar Pathak ◽  
Sagar Kumar ◽  
Chitresh Nayak ◽  
NRNV Gowripathi Rao
Keyword(s):  
Particle Swarm Optimization ◽  
Geometric Characteristic ◽  
Particle Swarm ◽  
Surface Characteristics ◽  
Planar Surface ◽  
Swarm Optimization ◽  
Geometric Characteristics ◽  
Form And Function ◽  
Modified Particle Swarm Optimization ◽  
Planar Surfaces

AbstractThis paper presents a modified particle swarm optimization (MPSO) algorithm for the evaluation of geometric characteristics defining form and function of planar surfaces. The geometric features of planar surfaces are decomposed into four components; namely straightness, flatness, perpendicularity, and parallelism. A non-linear minimum zone objective function is formulated mathematically for each planar surface geometric characteristic. Finally, the result of the proposed method is compared with previous work on the same problem and with other nature inspired algorithms. The results demonstrate that the proposed MPSO algorithm is more efficient and accurate in comparison to other algorithms and is well suited for effective and accurate evaluation of planar surface characteristics.

scholarly journals Wheelset/rail geometric characteristics and contact forces assessment with regard to angle of attack

2019 ◽  
Vol 254 ◽  
pp. 01014 ◽  
Author(s):  
Tomáš Lack ◽  
Juraj Gerlici ◽  
Pavol Šťastniak
Keyword(s):  
Gamma Function ◽  
Geometric Characteristic ◽  
Angle Of Attack ◽  
Contact Forces ◽  
Geometric Characteristics ◽  
Contact Points ◽  
Current State ◽  
Geometric Relation ◽  
Equivalent Conicity

The geometric relation between a wheelset and a rail is assessed with the help of geometric characteristics. Geometric characteristics are: equivalent conicity function, delta r function placement of contact points of a wheelset and a rail, tangent gamma function and effective conicity. It turned out that these characteristics are at present the most important not only for the judgment of ride characteristics of a vehicle on the rail but also for the wearing of wheel treads and rail heads, i.e., for the assessment of the track and vehicles in order to find out the current state and for the assessment of changes of the wheels and rails profile shapes in order to improve the current state too. The process of geometric characteristic assessment of a wheelset and rail with regard to angle of attack, as well as contact forces are analysed in the article.

Machining of a Rock Surface Shaver with a Piezoelectric Actuator forIn situAnalysis in Lunar and Planetary Exploration

2016 ◽  
Vol 10 (4) ◽  
pp. 533-539 ◽  
Author(s):  
Katsushi Furutani ◽  
◽  
Eiji Kagami ◽  
Keyword(s):  
Surface Roughness ◽  
Piezoelectric Actuator ◽  
Thrust Force ◽  
Sample Surface ◽  
Rock Surface ◽  
Composition Analysis ◽  
Machining Performance ◽  
Asteroid Exploration ◽  
Offset Voltage

Future lunar, planetary, and asteroid exploration will strongly demandin situanalysis of rock samples to obtain data related to various aspects. For precise composition analysis, a sample surface should be smoothed. In this paper, a surface shaver with a piezoelectric actuator is proposed and its machining performance in air is investigated. Shaving teeth are mounted at the ends of a pair of lever mechanisms. The device is pressed through four springs onto the workpiece with a linear actuator. When a sinusoidal voltage of 50 Vp-pand an offset voltage of 25 V were applied, the resonance frequency was 556 Hz and the unloaded amplitude of the shaving teeth was 0.77 mmp-p. Basalt workpieces were machined for 10 min in air. Increasing the thrust force reduced the surface roughness, although the amount removed diminished with a further increase in the thrust force. The surface roughness varied widely not only due to the amount removed but also due to containing the pores.

scholarly journals Rock Sample Surface Preparation Influences Thermal Infrared Spectra

2018 ◽  
Author(s):  
Evelien Rost ◽  
Christoph Hecker ◽  
Martin C. Schodlok ◽  
Freek D. van der Meer
Keyword(s):  
Surface Roughness ◽  
Rock Sample ◽  
Surface Preparation ◽  
Thermal Infrared ◽  
Sample Surface ◽  
Spectral Shape ◽  
Spectral Signature ◽  
Rock Surface ◽  
Spectral Signatures ◽  
Spectral Contrast

High-resolution laboratory-based thermal infrared spectroscopy is an up-and-coming tool in the field of geological remote sensing. Its spatial resolution allows for detailed analyses at centimeter to sub-millimeter scale. However, this increase in resolution creates challenges with sample characteristics such as grain size, surface roughness and porosity that can influence the spectral signature. This research explores the effect of rock sample surface preparation on the TIR spectral signatures. We applied three surface preparation methods (split, saw and polish) to determine how the resulting differences in surface roughness affects both the spectral shape as well as the spectral contrast. The selected samples are a pure quartz sandstone, a quartz sandstone containing a small percentage of kaolinite, and an intermediate-grained gabbro. To avoid instrument or measurement type biases we conducted measurements on three TIR instruments, resulting in directional hemispherical reflectance spectra, emissivity spectra and bi-directional reflectance images. Surface imaging and analyses were performed with scanning electron microscopy and profilometer measurements. We demonstrate that surface preparation affects the TIR spectral signatures influencing both the spectral contrast as well as the spectral shape. The results show that polished surfaces predominantly display a high spectral contrast while the sawed and split surfaces display up to 25% lower reflectance values. Furthermore, the sawed and split surfaces display spectral signature shape differences at specific wavelengths, which we link to mineral transmission features, surface orientation effects and multiple reflections in fine-grained minerals. Hence, the influence of rock surface preparation should be taken in consideration to avoid an inaccurate geological interpretation.

scholarly journals Measurement of Heat Transfer from Anodic Oxide Film on Aluminum in High Knudsen Number Flows

Micromachines ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 234 ◽  
Author(s):  
Hiroki Yamaguchi ◽  
Kenji Kito
Keyword(s):  
Heat Transfer ◽  
Oxide Films ◽  
Sample Surface ◽  
Anodic Oxide ◽  
Heat Fluxes ◽  
Molecular Flow ◽  
Sem Images ◽  
Anodic Oxide Films ◽  
Energy Accommodation ◽  
Accommodation Coefficients

The heat transfer in vacuum depends on the gas–surface interaction. In this study, the heat flux from anodic oxide films on aluminum with different anodizing times through a gas confined between two surfaces with different temperatures was studied. We prepared a non-treated surface, a surface with a normal anodizing time of 30 min, and a surface with 90 min, where the formed film would partially dissolve by long time exposure to the solution. The formation of the films was checked by electrical resistance. Scanning electron microscope (SEM) images were obtained for the three sample surfaces. Even though it was difficult to observe the hexagonal cylindrical cell structures on anodic oxide films, the 30 min sample surface was shown to be rough, and it was relatively smooth and powdery for the 90 min sample surface. The heat fluxes from three sample surfaces were measured from the free-molecular to near free-molecular flow regimes, and analyzed to obtain the energy accommodation coefficients. The heat fluxes were well fitted by the fitting curves. The energy accommodation coefficients for both helium and argon increased by anodizing an aluminum sample surface, while they decreased with increasing the anodizing time up to 90 min indicating the dissolution of the film.

Examination of the Surface of a Maldi-Ftms Probe Tip using SEM and Determination of Detection Limits for Poly(Ethylene Glycol)

1998 ◽  
Vol 4 (S2) ◽  
pp. 496-497
Author(s):  
Sylvia H. Wood ◽  
Salvador J. Pastor ◽  
Charles L. Wilkins
Keyword(s):  
Mass Spectrometry ◽  
Sample Preparation ◽  
Structural Information ◽  
Detection Limits ◽  
Sample Surface ◽  
Sem Images ◽  
Molecular Weight Distributions ◽  
Sample Spot ◽  
Sample Characterization ◽  
Poly Ethylene

Exploratory synthetic strategies may yield limited quantities of sample. Characterization of such limited-quantity samples is facilitated by the use of sensitive analytical methods and smart sample preparation. Polymers may be analyzed by mass spectrometry for molecular weight distributions, structural information (such as endgroups), and impurities. However, polymer research using mass spectrometry has not focused on detection limits; in some work the amount of polymer used is not even mentioned. Studies to determine detection limits of polymers and studies that characterize sample preparation techniques can provide valuable information.Examination of the sample surface on a probe tip, generated by the use of an aerospray technique for sample deposition, was accomplished by scanning electron microscopy (SEM). Aerospraying the polymer and matrix solutions allowed signal averaging of mass spectra from up to 400 shots on the same sample spot. SEM images showed the surface of the probe to have a fairly uniform coating of the sample and matrix.

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