Equivalent Diameter Distribution Research Articles

Size distributions of cellulose nanocrystals in dispersions using the centrifugal sedimentation method

Nanocellulose is a remarkable biomaterial. It is a plastic alternative with significance from the viewpoint of carbon offset and neutrality. To efficiently develop nanocellulose-based functional materials, it is imperative to evaluate their dispersion states. In this study, the sedimentation equivalent diameter distributions of cellulose nanocrystals (CNC) are analyzed by centrifugal sedimentation. The diameter distribution is well correlated with that estimated from the widths and the lengths of the CNCs obtained by transmission electron microscopy. Hence, centrifugal sedimentation has the potential to assess the dispersion states of nanocellulose on the nanometer scale and should contribute to basic research and applications.

Study on the distribution and connectivity of organic matter pores in Longmaxi shale based on 2D and 3D FIB‐SEM

AbstractKnowledge of shale pore structure characteristics is crucial to understand gas storage and seepage mechanisms. Organic matter (OM) pores are considered the most important pore type in shale, and one of the currently significant research questions focuses on the spatial distribution and connectivity of OM pores. To answer this question, typical OM‐rich siliceous shale samples from the Lower Silurian Longmaxi Formation were comprehensively investigated using focused ion beam scanning electron microscopy. A three‐dimensional model of the OM‐rich region of interest was segmented and reconstructed based on numerous two‐dimensional slices. The types of OM were found to control the development of organic pores, and OM pores including honeycomb‐shaped pores, spongy‐shaped pores, and slit‐like irregular pores are mainly formed in the pyrobitumen. The pore structure parameters of the OM‐rich ROI revealed that the pore size distribution of honeycomb‐shaped OM pores formed in the pyrobitumen was mainly distributed in the range of 10–50 and 80–100 nm, while the throat equivalent diameter distribution demonstrated a unimodal curve with the main peak located at approximately 30 nm. Pore connectivity analysis further indicated that pyrobitumen also contained several isolated nano‐pores, and pores with diameters smaller than 40 nm were poorly connected. Furthermore, permeability simulation revealed clear discrepancies in different directions owing to the heterogeneity of the OM pores. These findings provide experimental evidence for the assessment of shale gas resources and their development potential.

Multistep Super Resolution Double-U-net (SRDUN) for enhancing the resolution of Berea sandstone images

Digital Rock Physics (DRP) has opened a new avenue through the microscale world of rocks leading to more detailed inferences. However, High Resolution (HR) images are problematic from several aspects such as low field of view, huge memory and long time and high cost of image acquisition. Recent advances in Machine Learning (ML) and especially Convolutional Neural Networks (CNN) highly improved the ability of producing HR images from their Low Resolution (LR) counterparts known as Super Resolution (SR) images. In this procedure, the scale-difference between LR and HR images is a key parameter, while a high scale-difference leads to unreliable results regardless of the method. To overcome such a problem, we aim to both propose a multiscale procedure and introduce an efficient network namely Super Resolution Double-U-net (SRDUN). To this end, unlike conventional studies where LR images are synthetically produced from HR images, we capture these images from a Berea sandstone individually in five different scales (16.263, 12.922, 9.499, 5.775 and 3.501 μm for samples with a side of 10, 8, 6, 4 and 2-mm). Then, the SRDUN is introduced, where a first U-net is used to store feature maps of HR images and are imported in a second U-net as informative skip connections. Results show SRDUN could perform more accurate than common networks for small scale-differences. However, when it comes to high scale-differences it becomes more complicated. We propose a multistep procedure, where several mid-step SRDUNs are used to fill the gap of information. Results of this procedure reveal that the multistep procedure could perform much better than the direct approach. These results are then demonstrated by some computations of reservoir parameters such as porosity, pore equivalent diameter distribution, morphometric properties and permeability. Porosity and permeability computations showed that the error of computed values from SR images is increased by increasing scale-difference, however, the multistep procedure leads to more reliable results. The multistep procedure could preserve better the pore size distribution, however, in morphometric properties, the direct approach performs better since the multistep procedure suffers from a smoothing effect.

Mathematical simulation of two-phase flow and slag entrainment during steel bloom continuous casting

A three-dimensional computational model, coupled with the Large Eddy Simulation (LES) model and Volume of Fluid (VOF) multiphase model, was established to investigate the two-phase flow and slag entrainment during steel bloom continuous casting. The influence of the in-mold electromagnetic stirring (M-EMS), casting speed, and submerged entry nozzle (SEN) immersion depth on the flow pattern and slag entrainment were evaluated. The number, size, velocity, and spatial distribution of slag droplets were counted and the location, velocity and probability of the slag entrainment on the meniscus were exported in real time through a user defined function. The result shows that the slag entrainment mainly occurred around the 1/4 width of the mold. The equivalent diameter of most slag droplets was 2–6 mm under the current casting condition. A formula for the equivalent diameter distribution of slag droplets was proposed according to the statistical result.

Detection of framboidal pyrite size distributions using convolutional neural networks

Pyrite (FeS2) framboids, spheroidal groups of discrete equant pyrite microcrysts, are found in sediments of all geological ages. The size of a pyrite framboid is established during early diagenesis and preserved through time. Framboid size distributions are hence useful for the evaluation of depositional conditions. In this work, we present machine learning approaches to characterize the size distributions of pyrite framboids to understand the intensity and duration of anoxia and euxinia during the Middle Devonian of the Appalachian foreland basin by analyzing framboid size distributions of the Marcellus Shale from Lycoming County, Pennsylvania. Importantly, we overcome the time-consuming and laborious nature of current manual tracing methods to enable the processing of high volumes of micrograph data. Specifically, we implement convolutional neural networks (CNNs) to characterize framboids from 14 samples across depths in the Marcellus Shale. We show that CNNs enable the precise and fast measurement of framboid size distributions from scanning electron micrographs. CNN architectures including Inception, ResNet, Inception-Resnet, and Mask R-CNN were trained and tested on a total of ~6,800 framboids from 128 grayscale and 32 colored scanning electron micrographs. Kolmogorov-Smirnov tests on the framboidal equivalent diameter distributions measured from CNNs and manual tracing show that the CNN algorithms detected framboids with up to 99% precision. Importantly, once trained, the CNNs were ~100 times faster than current manual tracing. A straightforward extension of this work includes the application of CNNs to characterize pores, fractures, organic matter, and/or mineral grains in geological materials.

Digital Image Processing Method for Characterization of Fractures, Fragments, and Particles of Soil/Rock-Like Materials

Natural soil and rock materials and the associated artificial materials have cracks, fractures, or contacts and possibly produce rock fragments or particles during geological, environmental, and stress conditions. Based on color gradient distribution, a digital image processing method was proposed to automatically recognize the outlines of fractures, fragments, and particles. Then, the fracture network, block size distribution, and particle size distribution were quantitatively characterized by calculating the fractal dimension and equivalent diameter distribution curve. The proposed approach includes the following steps: production of an image matrix; calculation of the gradient magnitude matrix; recognition of the outlines of fractures, fragments, or particles; and characterization of the distribution of fractures, fragments, or particles. Case studies show that the fractal dimensions of cracks in the dry mud layer, ceramic panel, and natural rock mass are 1.4332, 1.3642, and 1.5991, respectively. The equivalent diameters of fragments of red sandstone, granite, and marble produced in quasi-static compression failures are mainly distributed in the ranges of 20–40 mm, 25–65 mm, and 10–35 mm, respectively. The fractal dimension of contacts between mineral particles and the distribution of the equivalent diameters of particles in rock are 1.6381 and 0.8–3.6 mm, respectively. The proposed approach provides a computerized method to characterize quantitatively and automatically the structure characteristics of soil/rock or soil/rock-like materials. By this approach, the remote sensing for characterization can be achieved.

Application of packed bed reactor theory and Bayesian inference to upweller culture of juvenile oysters

The use of upweller culture units in bivalve nurseries is widely practiced as a technique that enhances the ability to rear large quantities in a semi-controlled environment. However, guidance has varied for optimal flow rates, and thus there is a need to develop a more mechanistic assessment. The application of packed bed reactor theory, including axial diffusion models, would improve optimization of these culture methods. The following paper presents a series of controlled experiments to determine the hydrodynamic properties of a packed bed of oysters. The data gained from these experiments was used to develop mechanistic models calibrated through Bayesian inference. Specifically, the Ergun equation and the axial diffusion model were used to predict the experimental data. The Ergun equation was able to predict the hydrodynamic equivalent diameter distribution of oyster shells (μ = 3.18 mm, σ = 0.74 mm). This oyster shell diameter and void ratio distribution gained through the Ergun equation were used in the relationship of axial diffusion and superficial velocity. The mean axial diffusion coefficient in the oyster bed was estimated 1.65 × 104 m2/s at 0.01 m/s and 7.26 × 104 m2/s at 0.08 m/s. The use of Bayesian inference allows for greater understanding of the credibility of individual parameter distributions (i.e., rates and physical attributes) within these mechanistic formulations. This work establishes a baseline methodology to systematically evaluate and optimize bivalve upweller culture systems.

Light scattering matrix for soot aerosol: Comparisons between experimental measurements and numerical simulations

Fractal aggregate model has shown significant superiority in simulating integral optical properties (like optical cross sections etc.) of soot aerosol. In this study, angular distributions of scattering matrices for soot samples were measured at 532 nm wavelength. Experiments were conducted over scattering angles from 5° to 175° using an improved and validated apparatus. Soot particles emitted from burning of toluene and n-heptane were collected and re-aerosolized for matrix measurements. Electrical mobility diameter distributions of soot aggregates were measured and converted to volume equivalent diameter distributions according to various conversion factors. Size distributions of soot monomers and fractal parameters were obtained through statistical analyses of transmission electron microscope (TEM) images. Fractal aggregate models were generated by a tunable particle-cluster algorithm, using measured size distributions of aggregates and statistically obtained morphological parameters. Multiple sphere T-matrix (MSTM) method was employed for the calculation of individual particles, and bulk scattering matrices were integrated from particles with same morphology parameters. Results indicated that measured scattering matrices for these two soot samples show similar angular behaviors. Compared with fresh soot particles, the collection and re-aerosolization treatments lead to larger mobility diameters and more compact particle structures. Fractal parameter, conversion factor, refractive index and polydisperse monomer all have various effects on different matrix elements. Inter-comparisons between simulations and measurements focus more on the performance of ideal fractal model consisting of point-contact monomers in simulating measured scattering matrices, and there is no doubt that ideal fractal aggregates cannot simultaneously reproduce measured angular distributions of all matrix elements.

Scalable Freeze-Tape-Casting Fabrication and Pore Structure Analysis of 3D LLZO Solid-State Electrolytes.

Nonflammable solid-state electrolytes can potentially address the reliability and energy density limitations of lithium-ion batteries. Garnet-structured oxides such as Li7La3Zr2O12 (LLZO) are some of the most promising candidates for solid-state devices. Here, three-dimensional (3D) solid-state LLZO frameworks with low tortuosity pore channels are proposed as scaffolds, into which active materials and other components can be infiltrated to make composite electrodes for solid-state batteries. To make the scaffolds, we employed aqueous freeze tape casting (FTC), a scalable and environmentally friendly method to produce porous LLZO structures. Using synchrotron radiation hard X-ray microcomputed tomography, we confirmed that LLZO films with porosities of up to 75% were successfully fabricated from slurries with a relatively wide concentration range. The acicular pore size and shape at different depths of scaffolds were quantified by fitting the pore shapes with ellipses, determining the long and short axes and their ratios, and investigating the equivalent diameter distribution. The results show that relatively homogeneous pore sizes and shapes were sustained over a long range along the thickness of the scaffold. Additionally, these pores had low tortuosity and the wall thickness distributions were found to be highly homogeneous. These are desirable characteristics for 3D solid electrolytes for composite electrodes, in terms of both the ease of active material infiltration and also minimization of Li diffusion distances in electrodes. The advantages of the FTC scaffolds are demonstrated by the improved conductivity of LLZO scaffolds infiltrated with poly(ethylene oxide)/lithium bis(trifluoromethanesulfonyl)imide (PEO/LITFSI) compared to those of PEO/LiTFSI films alone or composites containing LLZO particles.

How Soil Pore Distribution Could Help in Soil Quality Studies as an Appropriate Indicator

The present study is aimed at examining the impacts of land use and slope gradient on pore space distribution as well as some soil physicochemical properties. Three land uses were considered in this research: natural forest lands, degraded forest lands, and cultivated lands as dry farming. The study area was divided into four slope classes. Furthermore, two types of soil surface (0–10 cm) sampling were performed: a) soil samples for physicochemical analysis and b) intact samples for thin section preparation and image analysis to extract pore equivalent diameter distribution. Pore diameters were divided into three classes, including macropores, mesopores, and micropores. One hundred and eight soil surface samples were collected from the study area. The results revealed that macropores and mesopores are predominant in the natural forest soils, while micropores are dominant in the cultivated soils. Moreover, the highest contents of soil organic matter (SOM) and cation exchangeable capacity and the lowest value of bulk density are observed in the natural forest soils. Regression analysis revealed a positive regression between SOM and macropores and mesopores and a negative regression between organic matter and micropores. These results indicated the importance of SOM in the formation of macropores and mesopores. It appears that plowing cultivated lands has led to the exposure and decay of SOM. In addition, agricultural machinery traffic affects soil compaction, both resulting in the formation of micropores. Overall, soil pore distribution has the essential sensitivity to detect changes in soil quality due to land use changes or other operations.

Detection of laser-induced bulk damage in optical crystals by swept-source optical coherence tomography

An approach to characterize laser-induced bulk damage in optical crystal materials was demonstrated. With a homemade swept-source optical coherence tomography (SS-OCT) system, we obtained three-dimensional images of the bulk damage produced by laser pulses with wavelength of 351 nm, pulse width of 5 ns, beam diameter of 5.5 mm and fluences from 4.56 J/cm2 to 9.95 J/cm2 in Potassium Dihydrogen Phosphate (KDP) crystal. Algorithms based on three-dimensional OCT images were specially designed to count and locate bulk damage pinpoints in KDP crystal, obtaining their equivalent diameter distribution and pinpoint density caused by different fluences. It is demonstrated that the characteristics of bulk damage detected by SS-OCT are similar to those obtained by available approaches. The rapid three-dimensional imaging by SS-OCT provides a new approach of detecting laser-induced bulk damage.

Modelling and characterization of ductile fracture surface in Al-Si alloys by means of Voronoi tessellation

In this study, a new approach to model the system of dimples on the fracture surface of Al-Si alloys using the weighted Voronoi tessellation is proposed. The tessellation model is applied to metallographic images of the eutectic phase to simulate a fracture surface appearance (as projected on a fractograph) that would potentially exhibit this structure if it had been fractured under uniaxial tensile loading. It enables the determination of geometrical features of virtual fracture surface projections, such as the dimple density, the area and equivalent diameter distributions, and topographic features, such as the dimple depth, the surface area and the roughness, by means of geometrical approximations, empirical and analytical relations. A brief review of the fractographic observations on different Al-Si alloys is made to demonstrate preconditions and motivation for using mosaic methods and in particular their weighted version. The simulation results are confirmed by experimental measurements indicating the credibility and usefulness of the model. The routine for generating the weighted Voronoi diagram is implemented as a Java plugin for the Fiji interface and is easy to execute.

High-resolution computed microtomography for the characterization of a diffusion tensor imaging phantom

This paper addresses the issue of the quantitative characterization of the structure of the calibration model (phantom) for b-matrix spatial distribution diffusion tensor imaging (BSD-DTI) scanners. The aim of this study was to verify manufacturing assumptions of the structure of materials, since phantoms are used for BSD-DTI calibration directly after manufacturing. Visualization of the phantoms’ structure was achieved through optical microscopy and high-resolution computed microtomography (µCT). Using µCT images, a numerical model of the materials structure was developed for further quantitative analysis. 3D image characterization was performed to determine crucial structural parameters of the phantom: porosity, uniformity and distribution of equivalent diameter of capillary bundles. Additionally calculations of hypothetical flow streamlines were also performed based on the numerical model that was developed. The results obtained in this study can be used in the calibration of DTI-BST measurements. However, it was found that the structure of the phantom exhibits flaws and discrepancies from the assumed geometry which might affect BSD-DTI calibration.

An experimental study of bubble sliding characteristics in narrow channel

An experimental investigation was conducted to study bubble sliding in subcooled flow boiling of water in a vertical narrow rectangular channel. Bubble behaviors were recorded using a high speed digital camera and an automatic digital image processing algorithm dealing with bubble sliding parameters (including bubble numbers, bubble velocities and bubble equivalent diameters) was proposed. The bubble image sequences were analyzed to obtain the distribution of bubble diameters and bubble velocities as well as their mean spatial-temporal value. Most of the bubbles in the experiments slide along the heated surface, but not lift off the surface, as is usual in a conventional channel. Two types of bubbles with different behaviors were observed in the experiments. The first type has a shorter lifetime and their diameters or volumes change a lot through rapid vaporizing and condensing. On the contrary, bubbles which were classified as the second type have a longer lifetime and their diameters or volumes change slowly. Bubble sliding velocity and bubble equivalent diameter distribution profiles were obtained based on the results of the automated analysis. The distribution of bubble sliding velocities and bubble equivalent diameters indicates that both of them cover a wide range. At last, mean bubble velocities, mean relative velocities between bubbles and local liquids and bubble densities under different working conditions were obtained to manifest the effects of mass flow rate, inlet subcooling and heat flux.

On Line Characterization of SiC Nanoparticles Produced by Laser Pyrolysis

On Line Measurements campaigns have been carried out for the first time in IRAMIS/SPAM CEA's laser gas-phase pyrolysis nanoparticles production facilities. The produced aerosol is composed of Argon and/or Helium laden with SiC nanoparticles concentrated up to ∼14 mg/l.Different commercial apparatus were used for sampling, and characterisation of size, and morphology of the particles. A series of experiment is performed by IRSN with a DMS500 from Cambustion Ltd™, which gives electrical mobility equivalent diameter distribution in real time. Particles are sampled with an ejector-diluter VKL-10 from Palas™. On the same sampling line, APTL performed aerodynamic equivalent diameter mass distribution using a Nanomoudi from MSP Corp.™ and TEM post analysis, as well as post elemental analysis (EDS) after collection on TEM grid with a Thermophoretic Precipitator (TP). A previously developed model is used to obtain the aggregate morphology and primary particles sizes.In addition to these commercial or well-known techniques, a new patent-pending technique called RFPM (Radio Frequency Plasma Metrology developed by CILAS + GREMI in the frame of NANOCARA program) is tested for the first time off the lab. The principle is based on levitation of particles in plasma RF. The entire set up is a prototype, including the sampling line. Experiments showed that this technique is very promising for on line gas phase monitoring, even though future improvements are needed, especially on the direct injection of the sample in the measuring chamber.First results of size distribution on pyrolysis line were obtained: three modes of different geometric mean diameter D50 were measured. Further analysis of TEM micrographs gave insight on these three modes, they can be interpreted as primary particles, aggregated particles, and a third one which could be composed of silica oxide nanoparticles issued from the combustion of the remaining silane initiated by an air leak in the exhaust of the reactor.Furthermore, a parametric study was undertaken. Helium addition in reactor and laser power were authorized to vary within a significant range. There was an evidence of influence of these parameters on the size distributions.Thus, we have demonstrated the high interest of implementing a size monitoring set up on gas phase nanoparticles production line for safety, yield improvement, and cost reduction purposes. This set up can run in a safe and non invasive way, and require low maintenance.

Studies on the effects of the enzymatic treatment on silk fine powder

In this study, the silk treated by steam explosion was pulverized into fine powder with a mean particle size of 1.829 μm, then the feasibility of the application of the protease treatment to produce finer and more uniform silk powder was investigated. The results indicated that after the enzymatic treatment, the mean diameter of the silk powder was reduced from 1.829 to 1.546 μm and the equivalent diameter distribution became more concentrated; thus, the uniformity of the particles was improved. The infrared spectra analysis demonstrated that the silk powder remained the β-sheet crystalline structure. X-ray diffraction analysis showed the crystallinity of the polished silk powder was very slightly strengthened. It was found that the treatment reduced some polar amino acid in the sericin; however, the composition of the kinds of the amino acids did not change. In addition, the hot water-solubility and moisture regain of the polished silk powder declined very slightly. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2967–2971, 2006

Transformation of Diffraction Pattern due to Ellipsoids into Equivalent Diameter Distribution for Spheres

If a particle is not spherical, the Fraunhofer diffraction pattern is not circular, however the particle size distribution obtained from conventional particle sizer are made under the assumption of spherical particle. It is, therefore, necessary to discuss or interpret the relationship between the obtained equivalent diameter and the diffraction pattern. In this paper, this transformation problem was discussed principally for the case of ellipsoid particle. A relationship between an original size of ellipsoid and obtained equivalent particle size distribution was given in an analytical expression. The equivalent particle size clearly had double peaks in the size corresponding both to the minor and major diameter of the original ellipsoid. On the other hand, if the original particle had its own size distribution, the double peak was eliminated due to the effect of this original size distribution. In the case of random orientation of the ellipsoid in the sensing zone, the double peak was also eliminated and a rather clear single peak appeared at the minor diameter of the original ellipsoid.

Quality control of the intrinsic deposition efficiency from the controls of the splat morphologies and the deposit microstructure

A simple heuristic model was developed to demonstrate the major characteristics of impinging particles prior to impact and during the spreading stages. It is based on the determination of transfer functions be-tween the powder particle size distribution and splat equivalent diameter distributions. The input data consist mainly of the aforementioned distributions, determined experimentally using a particle size ana-lyzer for powder particle size analysis and the wipe test for splat equivalent diameter analysis. Output data relate to the major characteristics of the impinging particles: flattening degree, intrinsic deposition efficiency, impact velocity, etc. Comparisons of the model predictions with experimental data showed rea-sonable agreement. Implementation of this simple protocol provides understanding of interactions dur-ing the process and also has technological and economical impacts. It permits quality control (QC) of deposition efficiency by control of splat morphologies and aids in the definition of specifications for the powders used (for example, in terms of the lower and upper limits of the particle size distribution leading to the formation of a deposit with given processing parameters) allowing the optimization of the spray pa-rameters to obtain high-integrity deposits.