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2018
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4 pages
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The fluidization technology has been closely related to traditional processes, such as petrochemical, pharmaceutical, polymer, food, and incineration (Kunii & Levenspiel, 1991). In these processes, the characterization of solid particles is vital to obtain higher efficiencies and lower process costs. Recently, many clean energy processes (e.g.: mechanical processes, pyrolysis, combustion, and gasification) involving biomass (non-woody and woody plants, and organic wastes) need fundamental parameters to understand energy conversion (physical, chemical, thermal and biological) in obtaining bio-fuels (gas, liquid or solid), electricity or heat. All of them require versatility in a wide range of chemical reactor configurations and designs (Cui & Grace, 2007;-Dai & Grace, 2011; Tannous e Lourenço, 2015). Fundamental parameters are necessary to understand the dynamic behavior of solids in these reactors because the particles have irregular non-spherical shapes. According to Guo, Chen, and...
2019
Particle size and shape are key factors influencing the properties of particulate and agglomerated materials, and having an impact on a quality as well as utilization of a final product. In case of plant biomass particle morphology is greatly irregular. Large errors at most determinations of biomass particle sizes are caused by simplification on a single parameter of size, assuming particle sphericity or circularity. Thus, the aim of a present research was to determine the particle size in a complex way. Pine sawdust as an experimental material and typical biofuel feedstock was ground by a hammer mill to a fraction size of 12 mm. The dimensional features of such ground sawdust particles were identified for all particles individually via photo-optical analysis, a method based on a digital image processing that is sensitive to irregular particles’ shapes. The particles were described mainly by variables of length, max width, equivalent diameter, max and min feret diameter, sphericity,...
Fuel
This study aims to provide a geometrical description of biomass particles that can be used in combustion models. The particle size of wood and herbaceous biomass was compared using light microscope, 2D dynamic imaging, laser diffraction, sieve analysis and focused beam reflectance measurement. The results from light microscope and 2D dynamic imaging analysis were compared and it showed that the data on particle width, measured by these two techniques, were identical. Indeed, 2D dynamic imaging was found to be the most convenient particle characterization method, providing information on both the shape and the external surface area. Importantly, a way to quantify all three dimensions of biomass particles has been established. It was recommended to represent a biomass particle in combustion models as an infinite cylinder with the volume-to-surface ratio (V/A) measured using 2D
Powder Technology, 1997
An image analysis method is presented which effectively describes the shape of a convex or concave particle. The method uses the Fourier descriptors evaluated from the Fourier series expansion of the angular bend of the periphery of a particle as a function of its arc length. The Fourier descriptors are then used as inputs to unsupervised or supervised artificial neural networks to cluster and classify particles according to their shape. A number describing the class of a single particle or the average class of a population of particles can therefore be deduced to characterize them.
Powder Technology, 1999
The main steps of characterisation of particle morphology by image analysis, i.e., visualisation, image treatment, shape quantification, for routine use in powder technology are reviewed and illustrated by examples. Macroscale and mesoscale bidimensional descriptors are presented, depending upon the desired level of detail. Elements for a quantification of the 3D shape are given, stressing out the special case of faceted
Granular Matter, 2017
Quantification of particle shape features to characterize granular materials remains an open problem till date, owing to the complexity involved in obtaining the geometrical parameters necessary to adequately compute the shape components (sphericity, roundness and roughness). A new computational method based on image analysis and filter techniques is proposed in this paper to overcome this difficulty. In this method, operations are performed on binary images of particles obtained from raster images (collection of pixels) by the process of image segmentation. The boundary of particles captured in 2D images consist of micro, meso and macro scale features on which filter techniques are applied to remove the micro level features for the quantification of particle roughness and to obtain a roughness free boundary. A robust algorithm is then written and implemented in MATLAB to obtain the complete geometry of the particle boundary (free from roughness features) and to identify the precise corner and non-corner regions along the boundary. This information is used to quantify the roundness (as per Wadell in J Geol 40:443-451, 1932) and sphericity of particles. The proposed methodology to measure roundness and sphericity is compared against standard visual charts provided by earlier researchers. Finally, the methodology is demonstrated on real soil particles falling across a wide range of sizes, shapes and mineralogical compositions. Also, an idea to comprehend the kinematics of particle motion based on its concavo-convex features is discussed with two proposed novel descriptors and a visual classification chart. Keywords Shape features • Image analysis • Kinematics • Corner and non-corner regions • Gaussian regression filter • Granular material
The growing success of image analysis based instruments for particle characterization demonstrates the importance of size and shape analysis in operations involving particulate materials. ISO norms for particle sizing using image analysis are being elaborated to clarify nomenclature and measurement principles. But despite this, there is still a lack of understanding of how the digital representation of a particle affects different size and shape parameters. It is the purpose of this paper to explore the magnitude of estimation errors of a series of size and shape parameters from different digital image representations of a single particle. These images are simulated from grey level images of black particles presenting a Gaussian transition towards their white background. Particles themselves are generated from analytical functions sampled by digital grids with variable densities, positions and orientations. Results of inscribed disk, elongation, circularity, roughness, roundness, etc. are plotted as a function of grid density (magnification) with error bars corresponding to the scattering of results for variable thresholds, grid translations and rotations As a conclusion, confidence intervals are given for parameters as a function of magnification and the most sensitive and robust methods of shape analysis are put forward.
Image Analysis & Stereology, 2012
During production of mechanical components, residual dirt collects on the surfaces, thus creating a contamination that affects the durability of the assembled products. Residual particles are currently analyzed based on microscopic 2D images. However, the particle's shape is decisive for the damage it can cause, yet can not be judged reliably from 2D data. Micro-computed tomography allows to capture the complex spatial structures of thousands of particles simultaneously. Now new methods to characterize three dimensional shapes are needed to establish 3D cleanliness analysis. In this work, unambiguously indicative geometric features are defined and it is investigated how they can yield a reliable classification in three typical classes: fibers, chips and granules. Finally, the efficiency of the proposed method is proved by analyzing samples of real dirt particles.
2021
The two objectives of this paper were to demonstrate use the of the discrete element method for generating synthetic images of spherical particle configurations, and to compare the performance of 9 classic feature extraction methods for predicting the particle size distributions (PSD) from these images. The discrete element code YADE was used to generate synthetic images of granular materials to build the dataset. Nine feature extraction methods were compared: Haralick features, Histograms of Oriented Gradients, Entropy, Local Binary Patterns, Local Configuration Pattern, Complete Local Binary Patterns, the Fast Fourier transform, Gabor filters, and Discrete Haar Wavelets. The feature extraction methods were used to generate the inputs of neural networks to predict the PSD. The results show that feature extraction methods can predict the percentage passing with a root-mean-square error (RMSE) on the percentage passing as low as 1.7%. CLBP showed the best result for all particle sizes with a RMSE of 3.8 %. Better RMSE were obtained for the finest sieve (2.1%) compared to coarsest sieve (5.2%).
Particulate Science and Technology, 2011
A machine vision has been devised for determination of the size distribution of spherically shaped pellets in granular beds under static and dynamic conditions. This machine vision involved establishing the optimal distance between the illumination source and the top layer of the granular bed, as well as the development of the data image acquisition software and control systems, I/O interface hardware, and electromechanical system. The size distribution of pellets given by the whole system gives an error lower than 5% for pellets. The size distribution histogram or the Sauter diameter of the pellets given by the vision system is used as the input signal for controlling an electromechanical scanning device, which can be reliably used for automation tasks. The system software was developed for open access on a commercially widely used platform. As the machine vision is robust, it can be used in industrial environments and it has the potential to contribute in improving and optimizing pelletizing industrial processes. This machine vision is reliable, flexible, user friendly, inexpensive, and easy to implement.
City, hinterland and environment: urban resiience during the first millennium transition. Edited by Simon Malmberg, Eivind Heldaas Seland and Christopher Prescott = Acta ad archaeologiam et artium historiam pertinentia 34.20d Open Access at https://journals.uio.no/acta/issue/view/858, 2024
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