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High-Order Two-Scale Asymptotic Paradigm for the Elastodynamic Homogenization of Periodic Composites

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Acta Mechanica Solida Sinica 2024年第1期37卷 124-138页

作者： Wei-Zhi Luo Mu He Liang Xia Qi-Chang He State Key Laboratory of Intelligent Manufacturing Equipment and Technology Huazhong University of Science and TechnologyWuhan 430074China Laboratoire Modélisation et Simulation Multi-Echelle MSME UMR 8208 CNRSUniversite Gustave Eiffel77454 Marne-la-ValléeFrance

The classical two-scale asymptotic paradigm provides macroscopic and microscopic analyses for the elastodynamic homogenization of periodic composites based on the spatial or/and temporal variable,which offers an approximate framework for the asymptotic homogenization analysis of the motion equation.However,in this framework,the growing complexity of the homogenization formulation gradually becomes an obstacle as the asymptotic order increases.In such a context,a compact,fast,and accurate asymptotic paradigm is developed.This work reviews the high-order spatial two-scale asymptotic paradigm with the effective displacement field representation and optimizes the implementation by symmetrizing the tensor to be determined.Remarkably,the modified implementation gets rid of the excessive memory consumption required for computing the high-order tensor,which is demonstrated by representative one-and two-dimensional cases.The numerical results show that(1)the contrast of the material parameters between media in composites directly affects the convergence rate of the asymptotic results for the homogenization of periodic composites,(2)the convergence error of the asymptotic results mainly comes from the truncation error of the modified asymptotic homogenized motion equation,and(3)the excessive norm of the normalized wavenumber vector in the two-dimensional inclusion case may lead to a non-convergence of the asymptotic results.

关键词： Composites Homogenization Asymptotic analysis Dynamics Dispersion

Sweetener and Flavor Enhancer Food Additives in Industrial Food Products Marketed in Dakar: Frequency and Diversity

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Open Journal of Applied Sciences 2024年第1期14卷 101-117页

作者： Alé Kane Alioune Sow Ndèye Adiara Ndiaye Coumba Gueye Sagna Papa Amadou Diakhaté Mady Cissé Amadou Diop Laboratoire des Sciences Biologiques Agronomiques Alimentaires et de Modélisation des Systèmes Complexes (LABAAM) Université Gaston Berger (UGB) Saint-Louis Senegal Département des Technologies Agroalimentaires|UFR des Sciences Agronomiques de l’Aquaculture et des Technologies Alimentaires (S2ATA) Saint-Louis Senegal Ecole Supérieure Polytechnique (ESP) Dakar Senegal Laboratoire de chimie analytique et bromatologie UCAD Dakar Senegal

Sweeteners and flavor enhancers are food additives widely used in industry, respectively, to add sweetness and flavor to foods. However, the presence of these substances is often criticized by consumers for their effects on health. What’s more, some scientific studies link these substances to certain pathologies. To guarantee food safety, competent authorities should have food standards based on risk analysis using consistent, reliable data. However, in developing countries, such data is often weak or non-existent. The aim of this study is therefore to carry out a pilot survey to establish the profile of sweeteners and flavour enhancers present in industrial food products marketed in Senegal. The methodology consisted of sampling various food products sold on the Senegalese market, based on analysis of labels containing information on ingredients, including additives. The investigation involved nine stores, one supermarket and 5 mini-markets in Dakar. The results showed the presence of 6 taste enhancers in food products, the most frequent being sodium L-monoglutamate (E621), inosinate (E631) and disodium guanylate (E627). Solid broths are the foodstuffs with the highest number of taste exhalters. As for sweeteners, 12 substances were identified, the most frequent being acesulfame potassium (E950), aspartame (E951), sucralose (E955) and saccharin (E954). Given the potential health risks associated with the consumption of these food additives, their control and monitoring on the market should be a priority for the competent authorities.

关键词： Exhalter Sugar Acesulfame Potassium Sodium Monoglutame Artificial Health Risk

Influences of nanoparticles and chain length on thermodynamic and electrical behavior of fluorine liquid crystals

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Chinese Physics B 2022年第10期31卷 410-416页

作者： Ines Ben Amor Lotfi Saadaoui Abdulaziz N.Alharbi Talal M.Althagafi Taoufik Soltani Université Tunis El Manar Laboratoire de Physique de la Matiére Molle et de la Modélisation Electromagnétique2092 Tunis Physics Department College of ScienceTaif UniversityP.O.Box 11099Taif 21944Saudi Arabia

Hydrogen-bonded polar nematic liquid crystal series with the general formula n OBAF(n = 7-12) is studied. The mesomorphic characterization is demonstrated through differential scanning calorimetry(DSC) and polarized optical microscopy(POM). The complexes with short alkyl chains(n = 7, 8) present a wide nematic range and monotropic smectic F mesophase, whereas the longer alkyl chain(n = 10-12) analogues show high melting and low clearing mesomorphic liquid crystals. The thermal range of the mesophase and the birefringence increase with chain length decreasing. Furthermore, the effect of the nanoparticles(LiNbO_(3)) on the thermal and the electrical behavior of 8OBAF are investigated. The presence of LiNbO_(3) nanoparticles increases the conductivity and reduces the resistivity of the complex.

关键词： fluorine liquid crystal polar nematic ferroelectric nanoparticles thermal stability dielectric behavior

Stochastic seismic response of multi-layered soil with random layer heights

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Earthquake Engineering and Engineering Vibration 2010年第2期9卷 213-221页

作者： M.Badaoui M.K.Berrah A.Mébarki Université Paris-Est Laboratoire Modélisation et Simulation Multi Echelle Ecole Nationale Polytechnique

This paper deals with the effect of layer height randomness on the seismic response of a layered soil. These parameters are assumed to be lognormal random variables. The analysis is carried out via Monte Carlo simulations coupled with the stiffness matrix method. A parametric study is conducted to derive the stochastic behavior of the peak ground acceleration and its response spectrum,the transfer function and the amplification factors. The input soil characteristics correspond to a site in Mexico City and the input seismic accelerations correspond to the Loma Prieta earthquake. It is found that the layer height heterogeneity causes a widening of the frequency content and a slight increase in the fundamental frequency of the soil profile,indicating that the resonance phenomenon is a concern for a large number of structures. Variation of the layer height randomness acts as a variation of the incident angle,i.e.,a decrease of the amplitude and a shift of the resonant frequencies.

关键词： random layer heights layered soil seismic acceleration lognormal distribution amplification factors Mexico City

Evaluation of Water Losses by Evaporation in the Nakanbe Basin

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Atmospheric and Climate Sciences 2024年第1期14卷 29-41页

作者： Bayala Alfred Kabre Sayouba Yonli Hamma Fabien Chesneau Xavier Thierry Sikoudouin Maurice Ky Zeghmati Belkacem Kieno P. Florent Kam Sié Unité de Formation et de Recherche en Sciences Exactes et Appliquées (UFR/SEA) Laboratoire d’Energies Thermiques Renouvelables (LETRE) Université Joseph KI-ZERBO Ouagadougou Burkina Faso Unité de Formation et de recherche en Science Exactes et Appliquées Centre Universitaire de Kaya (CU-K) Perpignan France Laboratoire de Modélisation Pluridisciplinaire et Simulation Université de Perpignan Via Domitia Perpignan France Unité de Formation et de Recherche en Sciences Exactes et Appliquées (UFR/SEA) Laboratoire de Matériaux et Environnement Uni-versité Joseph KI-ZERBO Ouagadougou Burkina Faso Laboratoire de Physique et Chimie de l’ Environnement (LPCE) Université Joseph KI-ZERBO Ouagadougou Burkina Faso

A numerical approach to heat and mass transfer in a large water reservoir is presented. This water reservoir is likened to a parallelepiped reservoir whose vertical and lower walls are adiabatic and impermeable. The equations that govern natural convection in water are solved by the finite volume method and Thomas’salgorithm. The adequacy between the velocity and pressure fields is ensured by the SIMPLE algorithm. We are going to evaluate the water losses by evaporation from three dams in the Nakanbé basin in Burkina Faso for a period of thirty years, that is to say from January 1, 1991, to March 15, 2020. The three dams have a rate of evaporation greater than 40% of the volume of water stored. Indeed the rate of evaporation in each dam increases with the water filling rate in the reservoir: we have observed the following results for each dam in the Nakanbé basin;for the date of 02/27/1988 to 03/13/2020., the Loumbila dam received a total volume of stored water of 22.02 Mm3 and 10.57 Mm3 as the total volume of water evaporated at the same date. At the Ouaga dam (2 + 3), it stored a water volume of 4.06 Mm3 and evaporated 2.03 Mm3 of its storage volume from 01/01/1988 to 05/07/2016. Finally, with regard to the Bagré dam, it stored 745.16 Mm3 of water and 365.13 Mm3 as the volume of water evaporated from 01/01/1993 to 03/31/2020.

关键词： Numerical Study Evaporation Meteorological Data Natural Convection Basins Dams

Maternal environment and seed size are important for successful germination and seedling establishment of Pterocarpus erinaceus (Fabaceae)

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Journal of Forestry Research 2022年第3期33卷 977-990页

作者： Beda Innocent Adji Doffou Sélastique Akaffou Philippe De Reffye Sylvie Sabatier Department for Seeds and Seedlings Production UniversitéJean Lorougnon GuédéAgroforestry UFRBP 150DaloaCôte d’Ivoire UMR-botAnique Et Modélisation de L’Architecture Des Plantes Et Des Végétations(AMAP) CIRADUniversitéMontpellierCNRSINRAE34398MontpellierIRDFrance

Seed size and the growth environment are important variables that influence seed germination, growth and biomass of seedlings and future tree harvest and should thus be taken into account in agroforestry and reforestation programmes for endangered species like Pterocarpus erinaceus. In the present study, to assess seedling germination and vigour in P. erinaceus as a function of seed size in two environments, 1080 seeds and 360 seedlings were evaluated at two separate sites in Côte d'Ivoire. The results show that large seeds had very high germination rates (up to 100%) and produced more vigorous plants better able to adapt to climate change. The maternal environment and seed size had a significant influence on seed germination (P < 0.05) and seedling development (P < 0.05) and biomass (P < 0.05). Seedlings were most successful at the site with a humid tropical climate (Daloa). Seedling leaves had the same resistance regardless of seed size and study site, but leaf moisture content was more stable in seedlings grown from medium and small seeds. These results will help guide conservation strategies for the species and are key factors for rural populations, loggers, and forest management structures for the silviculture of this species.

关键词： Pterocarpus erinaceus Seed size Germination performance Seedling Growth

A branching heuristic for SAT solvers based on complete implication graphs

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Science China(Information Sciences) 2019年第7期62卷 170-182页

作者： Fan XIAO Chu-Min LI Mao LUO Felip MANYA Zhipeng Lü Yu LI School of Computer Science Huazhong University of Science and Technology Modélisation Information et Systèmes (MIS) University of Picardie Jules Verne

The performance of modern conflict-driven clause learning(CDCL) SAT solvers strongly depends on branching heuristics. State-of-the-art branching heuristics, such as variable state independent decaying sum(VSIDS) and learning rate branching(LRB), are computed and maintained by aggregating the occurrences of the variables in conflicts. However, these heuristics are not sufficiently accurate at the beginning of the search because they are based on very few conflicts. We propose the distance branching heuristic, which,given a conflict, constructs a complete implication graph and increments the score of a variable considering the longest distance between the variable and the conflict rather than the simple presence of the variable in the graph. We implemented the proposed distance branching heuristic in Maple LCM and Glucose-3.0, two of the best CDCL SAT solvers, and used the resulting solvers to solve instances from the application and crafted tracks of the 2014 and 2016 SAT competitions and the main track of the 2017 SAT competition. The empirical results demonstrate that using the proposed distance branching heuristic in the initialization phase of Maple LCM and Glucose-3.0 solvers improves performance. The Maple LCM solver with the proposed distance branching heuristic in the initialization phase won the main track of the 2017 SAT competition.

关键词： SAT branching heuristic conflict-driven clause learning implication graph

Relative Dielectric Permittivity Variations during Compaction as a Mean of Compaction Quality Control: Case Study on Laterite Samples from Senegal

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International Journal of Geosciences 2023年第2期14卷 238-250页

作者： Mapathé Ndiaye Makhaly Ba Teophile Kiendrebeogo Linda E. Gaffo Foudjo Laboratoire de Mécanique et de Modélisation Université de Thiès Sénégal

This study explores an alternative to the classical use of direct methods, as water content and dry density measurements, for compaction quality control. For this purpose, the dielectric properties of lateritic materials are determined by radar method and are compared with the permittivity determined from the Topp formula and from the CRIM model. This approach allowed to establish a relationship between the geotechnical properties determined during compaction such as dry density, water content or porosity with dielectric permittivity. The obtained results made it possible to determine an optimum dielectric permittivity corresponding to the optimum dry density and the optimum water content that could be used for non-destructive in situ compaction testing. Such an approach should improve the implementation and effectiveness of in situ compaction quality control of geotechnical infrastructures.

关键词： Laterite Proctor Water Content Dry Density Dielectric Permittivity

Elastoplastic homogenization of particulate composites complying with the Mohr–Coulomb criterion and undergoing isotropic loading

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Acta Mechanica Sinica 2015年第3期31卷 392-405页

作者： D.Yang Q.C.He School of Mechanical Engineering Southwest Jiaotong University Université Paris-Est Laboratoire Modélisation et Simulation Multi Echelle UMR 8208 CNRS

This work aims at determining the overall response of a two-phase elastoplastic composite to isotropic loading. The composite under investigation consists of elastic particles embedded in an elastic perfectly plastic matrix governed by the Mohr-Coulomb yield criterion and a non-associated plastic flow rule. The composite sphere assemblage model is adopted, and closed-form estimates are derived for the effective elastoplastic properties of the composite either under tensile or compressive isotropic loading. In the case when elastic particles reduce to voids, the composite in question degenerates into a porous elastoplastic material. The results obtained in the present work are of interest, in particular, for soil mechanics.

关键词： Composite Porous medium. Elastoplasticity Mohr-Coulomb yield criterion Non-associated flow rule Homogenization