We have studied macerated xylem of ferns, supplemented by sections, by means of scanning electron microscopy (SEM) in a series of 20 papers, the results of which are summarized and interpreted here. Studies were based mostly on macerations, but also on some sections; these methods should be supplemented by other methods to confirm or modify the findings presented. Guidelines are cited for our i...

We review physical and chemical constraints on the mechanisms of melt extraction from the mantle beneath mid-ocean ridges. Compositional constraints from MORB and abyssal peridotite are summarized, followed by observations of melt extraction features in the mantle, and constraints from the physical properties of partially molten peridotite. We address two main issues. (1) To what extent is melt...

We have developed a new method for using the observed starlight polarization and polarized submillimeter emission to constrain shapes porosities of interstellar grains. first present modified picket-fence approximation verify that it is sufficiently accurate modeling polarization. then introduce integral Πobs as measure overall strength starlight, efficiency Φ characterize effectiveness differe...

In this paper, the first-order shear deformation theory is used to derive theoretical formulations illustrating the nonlinear dynamic response of functionally graded porous plates under thermal and mechanical loadings supported by Pasternak’s model of the elastic foundation. Two types of porosity including evenly distributed porosities (Porosity-I) and unevenly distributed porosities (Porosity-...

Introduction: Most asteroids for which porosities have been inferred have porosities ranging from 20% to >50%, with a mean of ~30% porosity [1]. Porosity significantly affects the physical properties of rocks, including the strength, thermal conductivity, seismic velocity, and dielectric permeability. Some asteroids have high enough porosities to affect their internal structure, gravitational f...

The permeability and tortuosity of pore-scale two and three-dimensional random porous media were calculated using the Lattice Boltzmann method (LBM). Effects of geometrical parameters of medium on permeability and tortuosity were investigated as well. Two major models of random porous media were reconstructed by computerized tomography method: Randomly distributed rectangular obstacles in a uni...

Abstract In the present work, we investigated effect of geometry open cell foam material on value pressure drop and heat flux. We create models porous media with an ordered (FCC, BCC, SC) disordered (DEM) structure different values porosity: 0.7; 0.75; 0.8. Numerical modeling was carried out in ANSYS Fluent software (v. 19.0) for various air flow velocities. At porosities 0.7 0.75 there is a no...

The novelty of the present work is to study simultaneous influence porosities and partial Pasternak foundation support on dynamics functionally graded (FG) beams carrying a moving load. are made from an open-cell steel foam with symmetric asymmetric porosity distributions in thickness direction. Based refined third-order shear deformation theory, two-node beam element ten degrees freedom derive...