The Experts below are selected from a list of 8349 Experts worldwide ranked by ideXlab platform
Audrey Lucero - One of the best experts on this subject based on the ideXlab platform.
-
cross linguistic lexical grammatical and discourse performance on oral narrative retells among young spanish speakers
Child Development, 2015Co-Authors: Audrey LuceroAbstract:This study investigated relations among Microlevel and macrolevel domains of oral narrative retells within and across the languages of Spanish-speaking bilingual children. Fifty-six first and second graders (Mage = 7 years, 3 months) were assessed on a retell task in Spanish and English. Two statistical analyses were conducted: (a) correlations within and across Microlevel lexical (number of different words) and grammatical (mean length of utterance-word and subordination index) domains and (b) hierarchical regression to determine the influence of Microlevel domains on a macrolevel discourse score. Results highlighted a number of significant within- and cross-language correlations, and identified vocabulary as a significant predictor of macrolevel discourse scores within both languages, while grammar was a predictor within English only.
-
Cross‐Linguistic Lexical, Grammatical, and Discourse Performance on Oral Narrative Retells Among Young Spanish Speakers
Child development, 2015Co-Authors: Audrey LuceroAbstract:This study investigated relations among Microlevel and macrolevel domains of oral narrative retells within and across the languages of Spanish-speaking bilingual children. Fifty-six first and second graders (Mage = 7 years, 3 months) were assessed on a retell task in Spanish and English. Two statistical analyses were conducted: (a) correlations within and across Microlevel lexical (number of different words) and grammatical (mean length of utterance-word and subordination index) domains and (b) hierarchical regression to determine the influence of Microlevel domains on a macrolevel discourse score. Results highlighted a number of significant within- and cross-language correlations, and identified vocabulary as a significant predictor of macrolevel discourse scores within both languages, while grammar was a predictor within English only.
Jurica Sorić - One of the best experts on this subject based on the ideXlab platform.
-
Two-scale computational approach using strain gradient theory at Microlevel
International Journal of Mechanical Sciences, 2017Co-Authors: Tomislav Lesičar, Zdenko Tonković, Jurica SorićAbstract:Abstract Realistic description of heterogeneous material behavior demands more accurate modeling at macroscopic and microscopic scales. In this frame, the multiscale techniques employing homogenization scheme offer several solutions. Most recently developed two-scale scheme employing second-order homogenization requires the nonlocal theory at the macrolevel, while the classical local continuum theory is kept at the Microlevel. In this paper, a new second-order computational homogenization scheme is proposed employing the higher-order theory at both macro- and Microlevel. Discretization is performed by means of the C 1 finite element developed using the strain gradient theory. The new gradient boundary conditions employed on representative volume element (RVE) are derived. The relation between the internal length scale parameter and the RVE size has been found. The new procedure is tested on a benchmark example, where the results have been compared to the solutions obtained by the usual second-order homogenization using the local concept on the RVE.
-
Multiscale Computational Approach Using Strain Gradient Formulation at Microlevel
2015Co-Authors: Tomislav Lesičar, Jurica Sorić, Zdenko TonkovićAbstract:A more realistic description of the deformation responses of heterogeneous materials demands more accurate modeling at both macroscopic and microscopic scales. The size, shape, spatial distribution, volume fraction and the properties of the constituents making up the microstructure have a significant impact on the material behavior observed at the macroscale. Strain localization phenomena and material softening as results of extreme loading conditions, may significantly decrease structural load-carrying capacity. Therefore, in order to assess structural integrity and reliability as well as to predict structural lifetime, an analysis on the Microlevel is unavoidable. Multiscale techniques employing several homogenization schemes have been proposed. The two-scale second-order homogenization approach has mostly been used, which requires C1 continuity in the discretization at macrolevel. The standard C0 continuity has been hold at Microlevel, where the solution of the boundary value problem of the representative volume element (RVE) has been performed. However, this C1 - C0 transition has some shortcomings. The Microlevel second-order gradient cannot be related to the macrolevel as volume average, and a modified second-order stress is extracted from the Hill-Mandel energy condition, which bring some inconsistences in the formulations and disturb accuracy. Furthermore, the localization and the material softening cannot be modeled at Microlevel without loss of ellipticity of governing field equations. The present contribution is concerned with a multiscale second-order computational homogenization algorithm employing C1 continuity at both macro- and Microlevels under assumptions of small strains and linear elastic material behavior. Discretization is performed by means of the C1 continuity finite element developed using strain gradient theory. A new scale transition methodology is derived in which the volume average of the macrolevel variables prescribed at the Microlevel is explicitly satisfied. The Hill Mandel condition yields the true state variables. The macroscopic consistent constitutive matrices are computed from the RVE global stiffness matrix using the standard procedures. The implemented strain gradient theory enables the modeling of damage response at the microstructural level, which is connected with strain localization and softening. The algorithms derived are implemented into FE software ABAQUS via user subroutines. The robustness and accuracy of the proposed homogenization approach is demonstrated by numerical examples.
-
Second-Order Computational Homogenization Approach Using Higher-Order Gradients at Microlevel
Key Engineering Materials, 2015Co-Authors: Tomislav Lesičar, Zdenko Tonković, Jurica SorićAbstract:Realistic description of heterogeneous material behavior demands more accurate modeling at macroscopic and microscopic scales. To observe strain localization phenomena and material softening occurring at the microstructural level, an analysis on the Microlevel is unavoidable. Multiscale techniques employing several homogenization schemes can be found in literature. Widely used second-order homogenization requires C1 continuity at the macrolevel, while standard C0 continuity has usually been hold at Microlevel. However, due to the C1-C0 transition macroscale variables cannot be defined fully consistently. The present contribution is concerned with a multiscale second-order computational homogenization employing C1 continuity at both scales under assumptions of small strains and linear elastic material behavior. All algorithms derived are implemented into the FE software ABAQUS. The numerical efficiency and accuracy of the proposed computational strategy is demonstrated by modeling three point bending test of the notched specimen.
Tomislav Lesičar - One of the best experts on this subject based on the ideXlab platform.
-
Two-scale computational approach using strain gradient theory at Microlevel
International Journal of Mechanical Sciences, 2017Co-Authors: Tomislav Lesičar, Zdenko Tonković, Jurica SorićAbstract:Abstract Realistic description of heterogeneous material behavior demands more accurate modeling at macroscopic and microscopic scales. In this frame, the multiscale techniques employing homogenization scheme offer several solutions. Most recently developed two-scale scheme employing second-order homogenization requires the nonlocal theory at the macrolevel, while the classical local continuum theory is kept at the Microlevel. In this paper, a new second-order computational homogenization scheme is proposed employing the higher-order theory at both macro- and Microlevel. Discretization is performed by means of the C 1 finite element developed using the strain gradient theory. The new gradient boundary conditions employed on representative volume element (RVE) are derived. The relation between the internal length scale parameter and the RVE size has been found. The new procedure is tested on a benchmark example, where the results have been compared to the solutions obtained by the usual second-order homogenization using the local concept on the RVE.
-
Multiscale Computational Approach Using Strain Gradient Formulation at Microlevel
2015Co-Authors: Tomislav Lesičar, Jurica Sorić, Zdenko TonkovićAbstract:A more realistic description of the deformation responses of heterogeneous materials demands more accurate modeling at both macroscopic and microscopic scales. The size, shape, spatial distribution, volume fraction and the properties of the constituents making up the microstructure have a significant impact on the material behavior observed at the macroscale. Strain localization phenomena and material softening as results of extreme loading conditions, may significantly decrease structural load-carrying capacity. Therefore, in order to assess structural integrity and reliability as well as to predict structural lifetime, an analysis on the Microlevel is unavoidable. Multiscale techniques employing several homogenization schemes have been proposed. The two-scale second-order homogenization approach has mostly been used, which requires C1 continuity in the discretization at macrolevel. The standard C0 continuity has been hold at Microlevel, where the solution of the boundary value problem of the representative volume element (RVE) has been performed. However, this C1 - C0 transition has some shortcomings. The Microlevel second-order gradient cannot be related to the macrolevel as volume average, and a modified second-order stress is extracted from the Hill-Mandel energy condition, which bring some inconsistences in the formulations and disturb accuracy. Furthermore, the localization and the material softening cannot be modeled at Microlevel without loss of ellipticity of governing field equations. The present contribution is concerned with a multiscale second-order computational homogenization algorithm employing C1 continuity at both macro- and Microlevels under assumptions of small strains and linear elastic material behavior. Discretization is performed by means of the C1 continuity finite element developed using strain gradient theory. A new scale transition methodology is derived in which the volume average of the macrolevel variables prescribed at the Microlevel is explicitly satisfied. The Hill Mandel condition yields the true state variables. The macroscopic consistent constitutive matrices are computed from the RVE global stiffness matrix using the standard procedures. The implemented strain gradient theory enables the modeling of damage response at the microstructural level, which is connected with strain localization and softening. The algorithms derived are implemented into FE software ABAQUS via user subroutines. The robustness and accuracy of the proposed homogenization approach is demonstrated by numerical examples.
-
Second-Order Computational Homogenization Approach Using Higher-Order Gradients at Microlevel
Key Engineering Materials, 2015Co-Authors: Tomislav Lesičar, Zdenko Tonković, Jurica SorićAbstract:Realistic description of heterogeneous material behavior demands more accurate modeling at macroscopic and microscopic scales. To observe strain localization phenomena and material softening occurring at the microstructural level, an analysis on the Microlevel is unavoidable. Multiscale techniques employing several homogenization schemes can be found in literature. Widely used second-order homogenization requires C1 continuity at the macrolevel, while standard C0 continuity has usually been hold at Microlevel. However, due to the C1-C0 transition macroscale variables cannot be defined fully consistently. The present contribution is concerned with a multiscale second-order computational homogenization employing C1 continuity at both scales under assumptions of small strains and linear elastic material behavior. All algorithms derived are implemented into the FE software ABAQUS. The numerical efficiency and accuracy of the proposed computational strategy is demonstrated by modeling three point bending test of the notched specimen.
P Sivakumar - One of the best experts on this subject based on the ideXlab platform.
-
fresh micro and macrolevel studies of metakaolin blended self compacting concrete
Applied Clay Science, 2015Co-Authors: O R Kavitha, V M Shanthi, Prince G Arulraj, P SivakumarAbstract:Abstract This investigation focuses on the effect of metakaolin (MK) on the fresh, micro- and macrolevel properties of self-compacting concrete (SCC). Cement content of 500 kg m − 3 was considered, while the MK was used to replace cement by 5, 10 and 15 wt.%. To assess the fresh concrete properties tests like slump flow, T 50 cm time, V-funnel flow times, L-box and blocking ratio were performed. The macrolevel properties studied were compressive strength and split tensile strength. The microstructural changes were studied using a Scanning Electron Microscope (SEM), X-ray Diffraction Analysis (XRD) and Energy Dispersive X-ray Analysis (EDX). The fresh concrete results show that SCC mixes prepared at different Water:Powder (W:P) ratios satisfied the rheological properties without addition of Viscosity Modifying Admixture (VMA). MK inclusion enhanced the macrolevel properties. The Microlevel studies indicated that microcrack width was reduced due to inclusion of MK in the control mix. In addition pozzolanic action of MK reduces the calcium hydroxide (CH) and lowers the calcium:silicate (Ca:Si) ratio of calcium silicate hydrate (C–S–H). The optimum replacement of MK was 10 wt.% regarding micro- and macrolevel properties. As a result of this evaluation, inclusion of MK improved the micro- and macrolevel properties.
Annie J Peter - One of the best experts on this subject based on the ideXlab platform.
-
micro and macrolevel properties of fly ash blended self compacting concrete
Materials & Design, 2013Co-Authors: Guru J Jawahar, C Sashidhar, I Ramana V Reddy, Annie J PeterAbstract:Abstract This investigation is mainly focused on the effect of class F fly ash on the micro and macrolevel properties of self compacting concrete (SCC) after 28, 56 and 112 days of curing. The Microlevel properties studied were the microcrack widths between aggregate and paste and atomic Calcium–Silica (Ca/Si) ratio. The macrolevel properties studied were compressive strength, modulus of elasticity and splitting tensile strength. A conventional concrete (CC) having an equivalent 28-day SCC compressive strength has also been examined at different ages. Scanning electron microscope (SEM) analysis was carried to examine the width of microcracks and energy dispersive X-ray analysis (EDAX) was carried out to determine the chemical elements of both SCC and CC. Studies revealed that pozzolanic action of class F fly ash improved the Microlevel properties of SCC with age by reducing the microcracking width and Ca/Si ratio and thus enhanced the macrolevel properties.
