In the present study, a six-directional sampling method (SDSM) and six-directional sampling mean mixing indices (SDS-mMI) i.e., SDS-mLMI, SDS-mRSD, and SDS-mSMI based on SDSM are proposed for the ...first time by considering Lacey mixing index (LMI), relative standard deviation (RSD) and sub-domain mixing index (SMI) as basis to assess the solids blending performance in DEM simulations. The proposed approach consists of dividing the blender into small grids, and accumulating the mass and mass contributions of each type of particle by moving in six different directions to generate predetermined number of samples, finding the mixing index in each direction, and finding the mean value of the index over all the six directions. The proposed approach is evaluated for two typical blenders with cohesive/cohesion-less, mono/bi-dispersed particles systems. The proposed mixing indices based on the sampling approach are compared with the same mixing indices based on BCSM, and also with other non-sampling indices.
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•Six-directional sampling method (SDSM) & mean mixing indices (SDS-mMI) are proposed.•SDSM applied and SDS-mMI computed for 50 L industrial bin-blender &14 L tote blender.•Cohesive & cohesion-less, mono & bi-dispersed particles considered as test cases.•SDS-mMI performance compared with BCSM, sub-domain, and non-sampling mixing indices.•Proposed SDSM based SDS-mRSD validated through experimental results from literature.
C1 density of stable ergodicity Avila, A.; Crovisier, S.; Wilkinson, A.
Advances in mathematics (New York. 1965),
03/2021, Letnik:
379
Journal Article
Recenzirano
Odprti dostop
We prove a C1 version of a conjecture by Pugh and Shub: among partially hyperbolic volume-preserving Cr diffeomorphisms, r>1, the stably ergodic ones are C1-dense.
To establish these results, we ...develop new perturbation tools for the C1 topology: linearization of horseshoes while preserving entropy, and creation of “superblenders” from hyperbolic sets with large entropy.
We show that there exists a polynomial automorphism f of C3 of degree 2 such that for every automorphism g sufficiently close to f, g admits a tangency between the stable and unstable laminations of ...some hyperbolic set. As a consequence, for each d≥2, there exists an open set of polynomial automorphisms of degree at most d in which the automorphisms having infinitely many sinks are dense. To prove these results, we give a complex analogous to the notion of blender introduced by Bonatti and Díaz.
•We developed an open-source workflow to characterize open-cell solid foams.•The geometry generation is performed by using the computer graphics code Blender.•Fluid flow and mass transfer are ...simulated using open-source CFD code OpenFOAM.•From the CFD results permeability and filtration rate are calculated.•The workflow (available online) is used to investigate a large number of different foams.
Open-cell foams are porous materials characterized by high porosity and large specific surface, industrially employed as catalyst supports or particulate filters. These materials can be modelled using periodic lattices, or with more complex approaches based on Voronoi tessellations. This work introduces, tests, and makes available an open-source workflow (Agostini, 2021) based on Blender that can reproduce great varieties of geometries with a limited cost for their modeling. An example of the exploration capabilities of this workflow is presented in the form of CFD simulations for flow field and mass transfer (performed with OpenFOAM) on the created geometries, eventually obtaining an effective particle deposition/filtration coefficient Kd. The results are interpreted using constitutive equations and other functional forms depending on geometric parameters which prove to be insufficient in explaining the variations in filtration performance, highlighting the need for more detailed exploration, the objective for which this workflow was developed.
Almost blenders and parablenders BIEBLER, SÉBASTIEN
Ergodic theory and dynamical systems,
04/2023, Letnik:
43, Številka:
4
Journal Article
Recenzirano
Odprti dostop
A blender for a surface endomorphism is a hyperbolic basic set for which the union of the local unstable manifolds robustly contains an open set. Introduced by Bonatti and Díaz in the 1990s, blenders ...turned out to have many powerful applications to differentiable dynamics. In particular, a generalization in terms of jets, called parablenders, allowed Berger to prove the existence of generic families displaying robustly infinitely many sinks. In this paper we introduce analogous notions in a measurable setting. We define an almost blender as a hyperbolic basic set for which a prevalent perturbation has a local unstable set having positive Lebesgue measure. Almost parablenders are defined similarly in terms of jets. We study families of endomorphisms of
$\mathbb {R}^2$
leaving invariant the continuation of a hyperbolic basic set. When an inequality involving the entropy and the maximal contraction along stable manifolds is satisfied, we obtain an almost blender or parablender. This answers partially a conjecture of Berger, and complements previous works on the construction of blenders by Avila, Crovisier, and Wilkinson or by Moreira and Silva. The proof is based on thermodynamic formalism: following works of Mihailescu, Simon, Solomyak, and Urbański, we study families of skew-products and we give conditions under which these maps have limit sets of positive measure inside their fibers.
To attain elevated class MXene (Ti3C2Tx) through a homemade kitchen blender method, high shear mechanical exfoliation is highly required for the efficient delimitations of MXene nanosheets from bulk ...MAX (Ti3AlC2). We examine large-scale industrial productions of the MXene nanosheets, where combing the predicted 2D materials using a blender is a first-time novel approach with the delaminating solvent as a dimethyl sulfoxide (DMSO). And also manually created layered MXene systems (handmade) delaminating MXene sheets (MX-H) was furthermore employed for environmental dye-degradations applications. The materials characterizations was done for both the bulk MAX, MX-H and the MX-B. Additionally, the surface morphological studies like scanning electron microscopy (SEM) were investigated for both MX-H and MX-B as-prepared samples. SEM images indicated the high shear blander technique formations highly expanded/delaminated MXene (Ti3C2Tx) nanosheets compared to MX-H samples. FTIR technique is employed to identify –OH, C–H, C–O stretching vibrations for both materials. Raman spectroscopy analysis of MX-H and MX-B revealed 484.80 cm−1 Raman shift assigned to E1g phonon mode of (Ti, C, O). The ultraviolet UV visible absorption spectra explored pure and catalyst added Methylene Blue (MB) dye stock solution using annular type photoreactor with visible light source of 300 W. The comparatives of MAX, MX-H and MX-B samples was investigated as photocatalytic activity, The blender made (MX-B) sample revealed 98% of efficiency.
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•Elevated class MXene (Ti3C2) attained via homemade kitchen blender.•High shear mechanical exfoliation is required for efficient MXene delimitations.•Large-scale industrial productions of the MXene nanosheets.•2D materials using a blender is a first-time novel approach.•The blender made (MX-B) sample revealed 98% of efficiency.
With the massive influx of patients during COVID-19 pandemic into intensive care unit, resources have quickly been stretched to the limit, including extracorporeal membrane oxygenation (ECMO). Gas ...blender attached to ECMO is used to allow precise adjustment of characteristics of fresh gas flow, that is, blood oxygen delivery and carbon dioxide removal. To cope with the gas blender shortage, we describe a back-up system set up in our French tertiary referral ECMO center using air and oxygen flowmeters. A table has been created to facilitate medical prescription but also nurse monitoring. This extraordinary situation forces physicians to adapt medical devices, and that could be useful in future viral pandemics.
Recently, the authors proved in C. Lizana and W. Ranter, Topological obstructions for robustly transitive endomorphisms on surfaces, Adv. Math. 390 (2021), pp. 107901 that every
$ C^1 $
C
1
-robustly ...transitive toral endomorphism displaying critical points must be homotopic to a linear endomorphism having at least one eigenvalue with modulus greater than one. Here, we exhibit some examples of
$ C^1 $
C
1
-robustly transitive surface endomorphisms displaying critical points in certain homotopy classes.
The shape and stacking method of the packing elements will affect the overall performance of the packed bed structure. In this study, the convection heat transfer in packed beds was simulated using ...the customized OpenFOAM “porousFoam_pimple” solver, which could provide the direction for the actual design and optimization of packed bed. Blender was used to generate the packed beds of spheres and fibers. Moreover, the influence of packed bed geometry on the convective heat transfer performance was investigated. The average pressure gradient and comprehensive heat transfer efficiency vary greatly with the parameters, such as fiber diameter, fiber axial, inlet velocity angle, and fiber interleaving degree. The customized “porousFoam_pimple” solver can be used for the numerical simulation of the convective heat transfer in packed beds with particles of different shapes under different operating conditions, providing a reliable and practical tool for the design and optimization of packed beds.
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•The study was conducted using an all-open-source approach.•The geometric modeling of packed bed was realized using Blender.•The solver for convective heat transfer in packed bed was developed based on OpenFOAM platform.•The fibrous diameter and degree of interlacing were studied for the optimization of convection in fibrous packed bed.
•In-silico generated random packings are used to successfully represent packed beds.•New constitutive equations for particle deposition are obtained.•Classical theory inadequate for 3D packings and ...for all mechanisms of deposition.•Polydisperse particles are considered: results very different from theoretical predictions.
In this work we have performed an extensive CFD simulation campaign with the purpose of studying particle transport and deposition in different catalytic systems and under different conditions. Two types of geometric models representing different porous media were created. The first is a number of random packings of spheres created via rigid body simulations: this approach was tested in previous studies and was proved to result in realistic packings, validated in their geometric features and fluid dynamic behaviour. The second is a regular arrangement of spheres, which was also successfully employed in previous works to study fine particles dispersion.
Using these random packings, simulations of particle deposition have been performed at different operating conditions. In the first part we calculated values of particle deposition efficiency and compared our results with the classical filtration theory, highlighting the criticalities in the use of the simplified models upon which the theory is based. In the second part we have studied the effect of polydisperse particle populations: this is also missing in the classical filtration theory, which always considers the transport of particles with uniform diameter. Thus, we have performed population balance modelling simulations for particle deposition, employing the quadrature method of moments (QMOM): as an accompanying technical addition, a study on the accuracy of the application of EQMOM in these systems is offered. Even more clearly in this case, the results show that the description of polydisperse populations has a very noticeable effect on the macro-scale description, which would dramatically improve the understanding of particle transport and deposition in filtration and catalytic processes.
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