The concept of permeability porous media is discussed, and a modification Kozeny's equation to include the effect effective porosity introduced. An analytical expression for specific surface area system constructed randomly placed identical obstacles with unrestricted overlap derived, lattice-gas cellular automaton method then used simulate dependence on permeability, tortuosity, flow Newtonian uncompressible fluid in this two-dimensional substance. simulated permeabilities can well be...

The concept of tortuosity fluid flow in porous media is discussed. A lattice-gas cellular automaton method applied to solve the a Newtonian uncompressible two-dimensional substance constructed by randomly placed rectangles equal size and with unrestricted overlap. clear correlation between average paths porosity has been found. \textcopyright{} 1996 American Physical Society.

We report the results of essentially ab initio simulations creeping flow through large three-dimensional random fiber webs that closely resemble fibrous sheets such as paper and nonwoven fabrics. The computational scheme used in this Letter is lattice-Boltzmann method contains no free parameters concerning properties porous medium or dynamics flow. computed permeability web found to be good agreement with experimental data, confirms depends exponentially on porosity over a range porosity.

Numerical micropermeametry is performed on three-dimensional porous samples having a linear size of approximately 3 mm and resolution 7.5 microm. One the microtomographic image Fontainebleau sandstone. Two are stochastic reconstructions with same porosity, specific surface area, two-point correlation function as sample. The fourth sample physical model that mimics processes sedimentation, compaction, diagenesis permeabilities these determined by numerically solving at low Reynolds numbers...

We introduce a new method for mesoscopic modeling of protein diffusion in an entire cell. This is based on the construction three-dimensional digital model cell from confocal microscopy data. The segmented into cytoplasm, nucleus, plasma membrane, and nuclear envelope, which environment motion modeled by fully numerical methods. Finer cellular structures that cannot be resolved with imaging technique, significantly affect motion, are accounted this assigning effective, position-dependent...

Obesity and osteoporosis, two possibly related conditions, are rapidly expanding health concerns in modern society. Both of them associated with sedentary life style nutrition. To investigate the effects diet-induced obesity voluntary physical activity we used high resolution micro-computed tomography (μCT) together peripheral quantitative computed (pQCT) to examine microstructure distal femoral metaphysis mice.Forty 7-week-old male C57BL/6J mice were assigned 4 groups: control (C), +...

Existing ultrasound devices for assessing the human tibia are based on detecting first arriving signal, corresponding to a wave propagating at, or close to, bulk longitudinal velocity in bone. However, long bones effectively irregular hollow tubes and should theoretically support propagation of more complex guided modes similar Lamb waves plates. Guided attractive because they propagate throughout bone thickness can potentially yield information material properties architecture. In this...

Capillary penetration of a wetting liquid in microtomographic image paper board, whose linear dimension was close to the average length wood fibers, simulated by lattice-Boltzmann method. In spite size system not being large with respect structural inhomogeneities sample, for unidirectional behavior described well that Lucas-Washburn equation, while radial capillary equation behavior. both cases depth front as function time followed power law over many orders magnitude. small droplets also...

Abstract. A particle-based computer simulation model was developed for investigating the dynamics of glaciers. In model, large ice bodies are made discrete elastic particles which bound together by massless beams. These beams can break, induces brittle behaviour. At loads below fracture, may also break and reform with small probabilities to incorporate slowly deforming viscous behaviour in model. This has advantage that it simulate important physical processes such as calving fracturing a...

Although carbon nanotubes consist of honeycomb carbon, they have never been fabricated from graphene directly. Here, it is shown by quantum molecular-dynamics simulations and classical continuum-elasticity modeling, that nanoribbons can, indeed, be transformed into means twisting. The chiralities the tubes thus can not only predicted but also externally controlled. This twisting route an opportunity for nanofabrication, easily generalizable to ribbons made other planar nanomaterials.

We present results from an experimental study on the kinetic roughening of slow combustion fronts in paper sheets. The sheets were positioned inside a chamber and ignited top to minimize convection effects. emerging videotaped digitized obtain their time-dependent heights. data analyzed by calculating two-point correlation functions saturated regime. Both growth exponents determined found consistent with Kardar-Parisi-Zhang equation, agreement recent theoretical work.

Quantum inverse methods are developed for the exact solution of models which describe N two-level atoms interacting with one mode quantized electromagnetic field containing an arbitrary number excitations M. Either a Kerr-type nonlinearity or Stark-shift term can be included in model, and it is shown that these two cases mapped from to other. The method provides general framework within many related problems similarly solved. Explicit formulae given Rabi splitting some M, on- off-resonance....

A generic model is introduced for brittle fragmentation in $D$ dimensions, and this shown to lead a fragment-size distribution with two distinct components. In the small limit scale-invariant size results from crack branching-merging process. At larger sizes becomes exponential as result of Poisson process, which introduces large-scale cutoff. Numerical simulations are used demonstrate validity $D=2$. Data laboratory-scale experiments quarry blastings granitic gneiss confirm its $D=3$....

Magnetization of small ferromagnetic clusters at finite temperatures has been studied using the Ising model and Monte Carlo techniques. The magnetization is reduced from bulk value, increases with external magnetic field cluster size. results explain qualitatively recent observations by de Heer, Milani, Chatelain reduction decreasing size average moment in iron clusters.

Abstract Lytic infection with herpes simplex virus type 1 (HSV-1) induces profound modification of the cell nucleus including formation a viral replication compartment and chromatin marginalization into nuclear periphery. We used three-dimensional soft X-ray tomography, combined cryogenic fluorescence, confocal electron microscopy, to analyse transformation peripheral during HSV-1 infection. Our data showed an increased presence low-density gaps in marginalized at late Advanced analysis...

Results of experiments on the dynamics and kinetic roughening one-dimensional slow-combustion fronts in three grades paper are reported. Extensive averaging data allows a detailed analysis spatial temporal development interface fluctuations. The asymptotic scaling properties, long length time scales, well described by Kardar-Parisi-Zhang (KPZ) equation with short-range, uncorrelated noise. To obtain more picture strong-coupling fixed point, characteristic KPZ universality class, universal...