scholarly journals A Novel Multi-Scale Particle Morphology Descriptor with the Application of SPHERICAL Harmonics

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3286
Author(s):  
Wei Xiong ◽  
Jianfeng Wang ◽  
Zhuang Cheng
Keyword(s):  
Surface Roughness ◽  
Scale Effect ◽  
Scale Effects ◽  
Particle Surface ◽  
Relative Length ◽  
Particle Morphology ◽  
Length Scale ◽  
Multi Scale ◽  
Rate Of Increase ◽  
Macro Scale

Particle morphology is of great significance to the grain- and macro-scale behaviors of granular soils. Most existing traditional morphology descriptors have three perennial limitations, i.e., dissensus of definition, inter-scale effect, and surface roughness heterogeneity, which limit the accurate representation of particle morphology. The inter-scale effect refers to the inaccurate representation of the morphological features at the target relative length scale (RLS, i.e., length scale with respective to particle size) caused by the inclusion of additional morphological details existing at other RLS. To effectively eliminate the inter-scale effect and reflect surface roughness heterogeneity, a novel spherical harmonic-based multi-scale morphology descriptor Rinc is proposed to depict the incremental morphology variation (IMV) at different RLS. The following conclusions were drawn: (1) the IMV at each RLS decreases with decreasing RLS while the corresponding particle surface is, in general, getting rougher; (2) artificial neural network (ANN)-based mean impact values (MIVs) of Rinc at different RLS are calculated and the results prove the effective elimination of inter-scale effects by using Rinc; (3) Rinc shows a positive correlation with the rate of increase of surface area RSA at all RLS; (4) Rinc can be utilized to quantify the irregularity and roughness; (5) the surface morphology of a given particle shows different morphology variation in different sections, as well as different variation trends at different RLS. With the capability of eliminating the existing limitations of traditional morphology descriptors, the novel multi-scale descriptor proposed in this paper is very suitable for acting as a morphological gene to represent the multi-scale feature of particle morphology.

Comparing Micro- and Macro-Level Rheological Properties of Polymeric and Reclaimed Asphalt Pavement-Modified Asphalt Binders

2021 ◽  
pp. 036119812110288
Author(s):  
Tandra Bagchi ◽  
Zahid Hossain ◽  
Mohammed Ziaur Rahaman ◽  
Gaylon Baumgardner
Keyword(s):  
Mechanical Properties ◽  
Scale Effects ◽  
Asphalt Pavement ◽  
Linear Trend ◽  
Asphalt Binders ◽  
Reclaimed Asphalt Pavement ◽  
Reclaimed Asphalt ◽  
Multi Scale ◽  
Macro Scale ◽  
Scale Properties

Multi-scale evaluation of the rheological and mechanical properties of asphalt binder has substantial importance in understanding the binder’s micro- and macro-scale properties. This study compares the macro- and micro-scale mechanistic properties of asphalt binders. Test samples used in this study include performance grade binders (PG 64-22) from two different sources along with their modified counterparts. The modifiers include polyphosphoric acid (PPA), styrene-butadiene-styrene (SBS), a combination of SBS and PPA, and reclaimed asphalt pavement. To achieve the goal of this study, atomic force microscope technology was utilized to estimate the asphalt binder’s micro-mechanical properties (e.g., Derjaguin, Muller, Toropov modulus and deformation). On the other hand, data on the macro-scale properties—such as rutting factor (G*/sinδ), consistency and penetration—of the selected binders were analyzed and compared with the aforementioned micro-level properties. The comparative analyses indicated that the micro-mechanical properties of asphalt binders followed a linear trend with the macro-scale properties. The findings of this study are expected to help researchers and pavement professionals in modeling asphalt materials when multi-scale effects are deemed to be necessary.

scholarly journals Scale effect challenges in urban hydrology highlighted with a distributed hydrological model

2018 ◽  
Vol 22 (1) ◽  
pp. 331-350 ◽  
Author(s):  
Abdellah Ichiba ◽  
Auguste Gires ◽  
Ioulia Tchiguirinskaia ◽  
Daniel Schertzer ◽  
Philippe Bompard ◽  
...  
Keyword(s):  
Scale Effect ◽  
Hydrological Model ◽  
Scale Effects ◽  
Model Performance ◽  
Scale Dependence ◽  
Urban Hydrology ◽  
Distributed Data ◽  
Hydrological Models ◽  
Multi Scale ◽  
Scale Modelling

Abstract. Hydrological models are extensively used in urban water management, development and evaluation of future scenarios and research activities. There is a growing interest in the development of fully distributed and grid-based models. However, some complex questions related to scale effects are not yet fully understood and still remain open issues in urban hydrology. In this paper we propose a two-step investigation framework to illustrate the extent of scale effects in urban hydrology. First, fractal tools are used to highlight the scale dependence observed within distributed data input into urban hydrological models. Then an intensive multi-scale modelling work is carried out to understand scale effects on hydrological model performance. Investigations are conducted using a fully distributed and physically based model, Multi-Hydro, developed at Ecole des Ponts ParisTech. The model is implemented at 17 spatial resolutions ranging from 100 to 5 m. Results clearly exhibit scale effect challenges in urban hydrology modelling. The applicability of fractal concepts highlights the scale dependence observed within distributed data. Patterns of geophysical data change when the size of the observation pixel changes. The multi-scale modelling investigation confirms scale effects on hydrological model performance. Results are analysed over three ranges of scales identified in the fractal analysis and confirmed through modelling. This work also discusses some remaining issues in urban hydrology modelling related to the availability of high-quality data at high resolutions, and model numerical instabilities as well as the computation time requirements. The main findings of this paper enable a replacement of traditional methods of “model calibration” by innovative methods of “model resolution alteration” based on the spatial data variability and scaling of flows in urban hydrology.

An Efficient Multi-Scale Modeling Method that Reveals Coupled Effects Between Surface Roughness and Roll-Stack Deformation in Cold Sheet Rolling

2021 ◽  
pp. 1-53
Author(s):  
Feng Zhang ◽  
Arif S Malik
Keyword(s):  
Surface Roughness ◽  
Finite Element ◽  
Rough Surface ◽  
Material Behavior ◽  
Sheet Rolling ◽  
Elastic Plastic ◽  
Multi Scale ◽  
Macro Scale ◽  
Surface Contact ◽  
Rough Surface Contact

Abstract In thin-gauge cold rolling of metal sheet, the surface roughness of work-rolls is known to affect the rolled sheet surface morphology, the required rolling load, and the roll wear. While modeling of rough surfaces using statistical asperity theory has been widely applied to problems involving semi-infinite solids, the application of asperity distributions and their elastic-plastic behavior has not been considered in roll-stack models for cold sheet rolling. In this work, a simplified-mixed finite element method (SM-FEM) is combined with statistical elastic-plastic asperity theory to study contact interference and coupling effects between a rough work-roll surface and the roll-stack mechanics in cold sheet rolling. By mixing equivalent rough-surface contact foundations, Hertz foundations, and Timoshenko beam stiffness, an approach is created to efficiently model interactions between the micro-scale asperities and the macro-scale roll-stack deformation. Nonlinearities from elastic-plastic material behavior of the asperities and the sheet, as well as changing contact conditions along the roll length, are also accommodated. Performance of the multi-scale SM-FEM approach is made by comparison to a continuum finite element virtual material model. 3D studies for a 4-high mill reveal new multi-scale coupling behaviors, including non-uniform roughness transfer, and perturbations to the sheet thickness ‘crown’ and contact force profiles. The described multi-scale SM-FEM approach is general and applies to rough surface contact problems involving plates and shear-deformable beams having multiple contact interfaces and arbitrary surface profiles.

A Study on Length Scale Effects on Indentation Delamination of Thin Films

2004 ◽  
Author(s):  
W. Li ◽  
S. Qu ◽  
T. Siegmund ◽  
Y. Huang
Keyword(s):  
Plastic Deformation ◽  
Strain Gradient ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Scale Effects ◽  
Scale Dependence ◽  
Zone Model ◽  
Length Scale ◽  
Gradient Plasticity ◽  
Elastic Substrates

Simulations of indentation delamination of ductile films on elastic substrates are performed. A cohesive zone model accounts for initiation and growth of interface delaminations and a strain gradient plasticity framework for the length scale dependence of plastic deformation. With the cohesive zone model and the strain gradient formulation two length scales are introduced in to the analysis.

Single-Phase Heat Transfer in Micro-Tubes: A Critical Review

2007 ◽  
Author(s):  
Chandramoulee Krishnamoorthy ◽  
Rahul P. Rao ◽  
Afshin J. Ghajar
Keyword(s):  
Heat Transfer ◽  
Surface Roughness ◽  
Single Phase ◽  
Review Paper ◽  
Measurement Techniques ◽  
Data Bank ◽  
Macro Scale ◽  
Small Scales ◽  
Gaseous Flows ◽  
Effect Of Surface

This review paper specifically concentrates on heat transfer in micro-tubes and eleven experiments (on liquid flow) and two experiments (on gaseous flow) from 1991 to 2007 are reviewed critically with respect to measurement techniques, instrumentation; and factors like surface roughness and diameter that may play an important role at these small scales. Moreover, a comprehensive list of numerical and analytical results (for both liquid and gaseous flows) is presented in this paper. Interestingly, the effect of surface roughness on heat transfer does not seem to have been investigated thoroughly, as it has been observed to play a key role in influencing heat transfer at small diameters. The state-of-art review thus provides the contemporary experimenters in the field of mini-micro channel heat transfer, this tabulated data that can be used to understand how the different parameters affect the heat transfer in these small scales and a data-bank to validate future numerical and experimental work. The present study identifies the various factors that have contributed in the disparity of results found in the literature and finds that there is a need to investigate certain issues like the effects of roughness, diameter, and secondary flow due to buoyancy on heat transfer and transition. Moreover, it was observed that the start and end of the transition region at these small diameters are not validated by the any of the existing macro-scale correlations.

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