1,517 research outputs found
Macroscopic behavior of bidisperse suspensions of noncolloidal particles in yield stress fluids
We study both experimentally and theoretically the rheological behavior of
isotropic bidisperse suspensions of noncolloidal particles in yield stress
fluids. We focus on materials in which noncolloidal particles interact with the
suspending fluid only through hydrodynamical interactions. We observe that both
the elastic modulus and yield stress of bidisperse suspensions are lower than
those of monodisperse suspensions of same solid volume fraction. Moreover, we
show that the dimensionless yield stress of such suspensions is linked to their
dimensionless elastic modulus and to their solid volume fraction through the
simple equation of Chateau et al.[J. rheol. 52, 489-506 (2008)]. We also show
that the effect of the particle size heterogeneity can be described by means of
a packing model developed to estimate random loose packing of assemblies of dry
particles. All these observations finally allow us to propose simple closed
form estimates for both the elastic modulus and the yield stress of bidisperse
suspensions: while the elastic modulus is a function of the reduced volume
fraction only, where is the estimated random loose
packing, the yield stress is a function of both the volume fraction and
the reduced volume fraction
Static behaviour of functionally graded sandwich beams using a quasi-3D theory
This paper presents static behaviour of functionally graded (FG) sandwich beams by using a quasi-3D theory, which includes both shear deformation and thickness stretching effects. Various symmetric and non-symmetric sandwich beams with FG material in the core or skins under the uniformly distributed load are considered. Finite element model (FEM) and Navier solutions are developed to determine the displacement and stresses of FG sandwich beams for various power-law index, skin-core-skin thickness ratios and boundary conditions. Numerical results are compared with those predicted by other theories to show the effects of shear deformation and thickness stretching on displacement and stresses
Water benefits sharing for poverty alleviation and conflict management: Topic 3 Synthesis Paper
Diffusion tensor model links to neurite orientation dispersion and density imaging at high b-value in cerebral cortical gray matter
Diffusion tensor imaging (DTI) and neurite orientation dispersion and density imaging (NODDI) are widely used models to infer microstructural features in the brain from diffusion-weighted MRI. Several studies have recently applied both models to increase sensitivity to biological changes, however, it remains uncertain how these measures are associated. Here we show that cortical distributions of DTI and NODDI are associated depending on the choice of b-value, a factor reflecting strength of diffusion weighting gradient. We analyzed a combination of high, intermediate and low b-value data of multi-shell diffusion-weighted MRI (dMRI) in healthy 456 subjects of the Human Connectome Project using NODDI, DTI and a mathematical conversion from DTI to NODDI. Cortical distributions of DTI and DTI-derived NODDI metrics were remarkably associated with those in NODDI, particularly when applied highly diffusion-weighted data (b-value = 3000 sec/mm2). This was supported by simulation analysis, which revealed that DTI-derived parameters with lower b-value datasets suffered from errors due to heterogeneity of cerebrospinal fluid fraction and partial volume. These findings suggest that high b-value DTI redundantly parallels with NODDI-based cortical neurite measures, but the conventional low b-value DTI is hard to reasonably characterize cortical microarchitecture
Using Educational Data to Increase Learning, Retention, and Degree Attainment at Minority Serving Institutions
Static and vibration analysis of functionally graded beams using refined shear deformation theory
Static and vibration analysis of functionally graded beams using refined shear deformation theory is presented. The developed theory, which does not require shear correction factor, accounts for shear deformation effect and coupling coming from the material anisotropy. Governing equations of motion are derived from the Hamilton's principle. The resulting coupling is referred to as triply coupled axial-flexural response. A two-noded Hermite-cubic element with five degree-of-freedom per node is developed to solve the problem. Numerical results are obtained for functionally graded beams with simply-supported, cantilever-free and clamped-clamped boundary conditions to investigate effects of the power-law exponent and modulus ratio on the displacements, natural frequencies and corresponding mode shapes
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