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diffuse approximation for identification of the mechanical properties of microcapsules

MATHEMATICS AND MECHANICS OF SOLIDS 2021年第7期26卷 1018-1028页

作者： Quesada, Carlos Dupont, Claire Villon, Pierre Salsac, Anne-Virginie Univ Technol Compiegne Biomech & Bioengn Lab UMR 7338 CNRS CS 60319 F-60203 Compiegne France Univ Technol Compiegne Roberval Lab Compiegne France

A novel data-driven real-time procedure based on diffuse approximation is proposed to characterize the mechanical behavior of liquid-core microcapsules from their deformed shape and identify the mechanical properties of the submicron-thick membrane that protects the inner core through inverse analysis. The method first involves experimentally acquiring the deformed shape that a given microcapsule takes at steady state when it flows through a microfluidic microchannel of comparable cross-sectional size. From the mid-plane capsule profile, we deduce two characteristic geometric quantities that uniquely characterize the shape taken by the microcapsule under external hydrodynamic stresses. To identify the values of the unknown rigidity of the membrane and of the size of the capsule, we compare the geometric quantities with the values predicted numerically using a fluid-structure-interaction model by solving the three-dimensional capsule-flow interactions. The complete numerical data set is obtained off-line by systematically varying the governing parameters of the problem, i.e. the capsule-to-tube confinement ratio, and the capillary number, which is the ratio of the viscous to elastic forces. We show that diffuse approximation efficiently estimates the unknown mechanical resistance of the capsule membrane. We validate the data-driven procedure by applying it to the geometric and mechanical characterization of ovalbumin microcapsules (diameter of the order of a few tens of microns). As soon as the capsule is sufficiently deformed to exhibit a parachute shape at the rear, the capsule size and surface shear modulus are determined with an accuracy of 0.2% and 2.7%, respectively, as compared with 2-3% and 25% without it, in the best cases (Hu et al. Characterizing the membrane properties of capsules flowing in a square-section microfluidic channel: Effects of the membrane constitutive law. Phys Rev E 2013;87(6): 063008). diffuse approximation thus allows the capsule size an

关键词： Identification mechanical properties microcapsules data-driven method diffuse approximation

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Identification of the mechanical properties of microcapsules using diffuse approximation 13

Identification of the mechanical properties of microcapsules...

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13th System of Systems Engineering Conference (SoSE)

作者： Quesada, Carlos Villon, Pierre Salsac, Anne-Virginie Univ Technol Compiegne CNRS BMBI Lab Sorbonne Univ Compiegne France Univ Technol Compiegne CNRS Roberval Lab Sorbonne Univ Compiegne France

ISBN: (纸本)9781538648766

A novel inverse analysis procedure based on diffuse approximation is presented to characterize the mechanical behavior of microcapsules. The method consists in flowing a dilute suspension of capsules through a prismatic microfluidic channel with a cross-section size comparable to the capsule diameter. For each capsule, we record its deformed profile and deduce from it a series of geometrical quantities and the capsule velocity. The unknowns are the membrane mechanical properties and the exact mean velocity of the background flow when the capsule is captured. A full mechanical model of the motion and deformation of a capsule is used to generate an exhaustive database of simulated profiles for different values of the input parameters: the capillary number and the size ratio. From the set of quantities obtained experimentally as well as the precomputed database, diffuse approximation efficiently estimates the unknown values of the input parameters of the flowing capsule. The shear modulus can then be determined with high precision provided that the capsule is sufficiently deformed to exhibit a parachute shape at the rear.

关键词： identification mechanical properties microcapsules diffuse approximation

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A rened analytical model for reconstruction problems in diuse reectance spectroscopy

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Journal of Innovative Optical Health Sciences 2024年第5期17卷 33-51页

作者： Ekaterina Sergeeva Daria Kurakina Ilya Turchin and Mikhail Kirillin A.V.gaponov-grekhov institute of applied physics of the russian academy of sciences ulyanov st.46 603950nizhny novgorodrussia

A rened analytical model of spatially resolved diffuse reectance with small source-detector separations(SDSs)for the in vivo skin studies is *** to the conventional model developed by Farrell et al.,it accounts for the limited acceptance angle of the *** rened model is validated in the wide range of optical parameters by Monte Carlo simulations of skin diffuse reectance at SDSs of units of *** of uniform dermis and two-layered epidermis-dermis structures are *** accuracy of the rened model compared to the conventional one is demonstrated in the separate,constraint-free reconstruction of absorption and reduced scattering spectra of uniform dermis from the Monte Carlo simulated *** the case of epidermis-dermis geometry,the recovered values of reduced scattering in dermis are overestimated and the recovered values of absorption are underestimated for both analytical ***,in the presence of a thin mismatched topical layer,only the effective attenuation coe±cient of the bottom layer can be accurately recovered using a diffusion theorybased analytical model while separate reconstruction of absorption and reduced scattering fails due to the inapplicability of the method of ***-ndings require implementation of more sophisticated models of light transfer in inhomogeneous media in the recovery algorithms.

关键词： diffuse reffectance spectroscopy in vivo skin studies optical properties reconstruction diffuse approximation Monte Carlo simulations method of images

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A bi-level meta-modeling approach for structural optimization using modified POD bases and diffuse approximation

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COMPUTERS & STRUCTURES 2013年第0期127卷 19-28页

作者： Raghavan, Balaji Hamdaoui, Mohamed Xiao, Manyu Breitkopf, Piotr Villon, Pierre CNRS Lab Roberval UMR 7337 F-60200 Compiegne France Northwestern Polytech Univ Dept Appl Math Xian 710072 Shaanxi Peoples R China

Managing computational effort (CPU time, memory, interfacing) is a major issue in design optimization, due to the cost of the high fidelity numerical simulations (finite elements, finite volumes, etc.) involved. In order to decrease the overall cost of the optimization process, reduced-order models such as Proper Orthogonal Decomposition (POD) are an economical and efficient option. However, truncating the POD basis yields an error in the calculation of the global values used as performance objectives and constraints which in turn affects the optimization results. This paper proposes novel constrained versions of Proper Orthogonal Decomposition that produce an alternative orthonormal basis, which is then successfully applied first to a 1D test-case with a quadratic constraint and next to an industrial example with both linear and quadratic constraints: the multi-objective shape optimization of an air-conditioning duct. (C) 2012 Civil-Comp Ltd and Elsevier Ltd. All rights reserved.

关键词： Constrained POD modes Shape optimization diffuse approximation

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Contrast Ratio during Visualization of Subsurface Optical Inhomogeneities in Turbid Tissues: Perturbation Analysis 8

Contrast Ratio during Visualization of Subsurface Optical In...

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14th International Joint Conference on Biomedical Engineering Systems and Technologies (BIOSTEC) / 8th International Conference on Bioimaging (BIOIMAGING)

作者： Saiko, Gennadi Douplik, Alexandre Ryerson Univ Dept Phys Toronto ON Canada

ISBN: (纸本)9789897584909

Visualization and monitoring of the capillary loops and microvasculature patterns in dermis and mucosa are of interest for various clinical applications, including early cancer and shock detection. We developed an approach for the assessment of the contrast ratio during the visualization of subsurface optical heterogeneities. Using the diffuse approximation and perturbation analysis, we considered light absorption heterogeneities as negative light sources. We estimated the contrast ratio as a function of the surface layer's optical properties for diffuse and collimated wide beam illumination. Based on findings, we formulated several practical suggestions: a) proper selection of camera (with maximum dynamic range) is of paramount importance, b) narrow-band illumination is more efficient than white light illumination, and c) use of collimated light provides up to 60% improvement in contrast vs. diffuse illumination. Obtained results can be used for the optimization of imaging techniques

关键词： Biomedical Imaging diffuse approximation Turbid Tissues

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A novel surrogate modeling strategy of the mechanical properties of 3D braided composites

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Chinese Journal of Aeronautics 2020年第10期33卷 2589-2601页

作者： Zeyi LIU Yuliang HOU Qiaoli ZHAO Cheng LI School of Mechanical and Power Engineering Zhengzhou UniversityZhengzhou 450001China

In this paper,a surrogate-based modeling methodology is developed and presented to predict the elastic properties of three dimensional(3 D)four-directional braided *** this approach,the prediction process becomes feasible with only a limited number of training *** surrogate models constructed using Finite Element(FE)method and diffuse approximation,reduce the computational time and cost for preparing experimental *** the FE model,multiscale method is applied to couple the computations of elastic properties at microscale and ***,a parametric study is performed to analyze the effects of the three design parameters on the elastic *** results are obtained via the surrogatebased modeling predictions,which are compared with the experimental ***,the predictions obtained from surrogate models concur well with the FE *** study orients a new direction for predicting the mechanical properties based on surrogate models which can effectively reduce the sample preparation cost and computational efforts.

关键词： Braided composites diffuse approximation Elastic properties Multiscale model Surrogate model

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A refined analytical model for reconstruction problems in diffuse reflectance spectroscopy

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JOURNAL OF INNOVATIVE OPTICAL HEALTH SCIENCES 2024年第5期17卷

作者： Sergeeva, Ekaterina Kurakina, Daria Turchin, Ilya Kirillin, Mikhail Russian Acad Sci AV Gaponov Grekhov Inst Appl Phys Ulyanov St 46 Nizhnii Novgorod 603950 Russia

A refined analytical model of spatially resolved diffuse reflectance with small source-detector separations (SDSs) for the in vivo skin studies is proposed. Compared to the conventional model developed by Farrell et al., it accounts for the limited acceptance angle of the detector fiber. The refined model is validated in the wide range of optical parameters by Monte Carlo simulations of skin diffuse reflectance at SDSs of units of mm. Cases of uniform dermis and two-layered epidermis-dermis structures are studied. Higher accuracy of the refined model compared to the conventional one is demonstrated in the separate, constraint-free reconstruction of absorption and reduced scattering spectra of uniform dermis from the Monte Carlo simulated data. In the case of epidermis-dermis geometry, the recovered values of reduced scattering in dermis are overestimated and the recovered values of absorption are underestimated for both analytical models. Presumably, in the presence of a thin mismatched topical layer, only the effective attenuation coefficient of the bottom layer can be accurately recovered using a diffusion theory-based analytical model while separate reconstruction of absorption and reduced scattering fails due to the inapplicability of the method of images. These findings require implementation of more sophisticated models of light transfer in inhomogeneous media in the recovery algorithms.

关键词： diffuse reflectance spectroscopy in vivo skin studies optical properties reconstruction diffuse approximation Monte Carlo simulations method of images

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Parameter identifiability of ductile fracture criterion for DP steels using bi-level reduced surrogate model

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ENGINEERING FAILURE ANALYSIS 2019年 100卷 300-311页

作者： Hou, Yuliang Zhao, Qiaoli Sapanathan, Thaneshan Dumon, Alexandre Rachik, Mohamed Zhengzhou Univ Sch Mech Engn Sci Rd 100 Zhengzhou 450001 Henan Peoples R China Univ Technol Compiegne Sorbonne Univ CNRS UMR7337 Lab RobervalCtr Rech Royallieu CS60319 F-60203 Compiegne France UCLouvain Inst Mech Mat & Civil Engn B-1348 Louvain La Neuve Belgium ESI Grp 99 Rue Solets F-94513 Rungis France

Generally, a large number of fracture tests are required to characterize the material parameters of the modified Mohr-Coulomb (MMC) fracture criterion. It takes enormous amount of time and expenses to prepare specimens and analyze experimental measurements. However, manufacturing industries are keen to seek fast and cost effective approaches. Therefore, a bi-level reduced surrogate model has been proposed as an alternative method for the parameter identification. Using this approach, the identification process becomes feasible and it requires only a limited number of experimental tests. The surrogate model is used in the current framework to empirically capture the non-linear evolution of material parameters for the fracture onset under the uniaxial loading condition. It assembles local critical elements associated with the global 3D finite element (FE) models. The surrogate model of fracture strain is constructed using diffuse approximation and the local elements to identify the unknown parameters. Then, global fracture simulations which consider the identified parameters, are preformed to update the target fracture strain and to compute the corresponding failure onset displacement. Satisfactory results are obtained by adopting the concept of successive Design of Experiments (DOE). The identification protocol is validated, and it is capable of calibrating ductile fracture parameters for different DP steels. Finally, a parametric study is performed to analyze the sensitivity of each free parameter and the influence of the used polynomial basis within the identification approach.

关键词： Surrogate model diffuse approximation Parameter identification Ductile fracture Successive DOE

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The effect of particle aspect ratio on spatially and angularly resolved vis-NIR spectroscopy of suspensions 4

The effect of particle aspect ratio on spatially and angular...

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Conference on Optical Methods for Inspection, Characterization, and Imaging of Biomaterials IV held at SPIE Optical Metrology Symposium

作者： Stoliarskaia, Daria Thomson, Kelly Lue, Leo Chen, Yi-chieh Univ Strathclyde Dept Chem & Proc Engn James Weir Bldg75 Montrose St Glasgow G1 1XJ Lanark Scotland

ISBN: (数字)9781510628007

ISBN: (纸本)9781510628007

The particle characteristics in a suspension affect the performance and quality of the end product of many chemical industries. The shape of the suspended particles can be influenced by changes in the manufacturing process conditions. Thus, there is a need for a robust method for continuous monitoring of particle characteristics through the process. This study investigates the feasibility of using spatially and angularly resolved diffuse reflectance measurements as a method of determining particle shape. A forward calculation was developed using the discrete dipole approximation to estimate optical properties of the single particle and the diffuse approximation for the reflectance of the particle suspension. The method was used to study aqueous suspensions of randomly-oriented polystyrene ellipsoids. Our objectives were to determine and elucidate the contribution of aspect ratio on optical measurement in vis-NIR spectra. The results suggest that the method is suitable for determining particle shape for suspensions where the particle and the solvent have significantly different optical properties. For these systems, the study suggests that diffusion reflectance measurements can be developed into an in-line method for particle shape determination

关键词： diffuse reflectance diffuse approximation DDSCAT aspect ratio

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A hybrid Meshless-FEM field transfer technique minimizing numerical diffusion and preserving extreme values: Application to ductile crack simulation

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FINITE ELEMENTS IN ANALYSIS AND DESIGN 2018年第Mar.期141卷 135-153页

作者： Yang, F. T. Rassineux, A. Labergere, C. Univ Technol Compiegne Sorbonne Univ Lab Roberval UMR CNRS UTC 7337 Ctr Rech Royallieu BP 20529 F-60205 Compiegne France Univ Technol Troyes UMR STMR 6279 ICD LASMIS 12 Rue Marie CurieBP2060 F-10010 Troyes France

We propose a hybrid 3D field transfer operator based on a moving least-squares meshless interpolation and designed to reduce numerical diffusion as well as to preserve extrema values during the adaptive analysis of a metal-forming process. An isotropic information point selection based on both distance and direction is implemented in the construction of the diffuse Interpolation to take account of the steep gradient of the physical field in highly localized zones. An information compensation process addresses the problems of loss of interpolation accuracy and lack of information points near the geometric boundary. Results of transferring an analytically highly localized field using different transfer operators are compared to show the improvement offered by our field transfer operator in situations where mesh gradation is large and field gradients are steep. Our method is implemented in an iterative 3D h-adaptive methodology to simulate metal-forming processes. Its effectiveness and robustness are validated through a simulation of crack initiation and propagation in a tensile test with a specimen made of rolled steel.

关键词： Field transfer Finite element method Meshless techniques diffuse approximation Isotropic point selection Ductile cracks

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