We study the entropy generation and particle production in scalar quantum field theory in expanding spacetimes with many-particle mixed initial states. The recently proposed coarse-grained entropy approach by Brandenberger et al. is applied to systems which may have a non-zero initial entropy. We find that although the particle production is amplified as a result of boson statistics, the (coars...

We explore the gap-tooth method for multiscale modeling of systems represented by microscopic physics-based simulators, when coarse-grained evolution equations are not available in closed form. A biased random walk particle simulation, motivated by the viscous Burgers equation, serves as an example. We construct macro-to-micro (lifting) and micro-to-macro (restriction) operators, and drive the ...

We have derived an equation of motion for coarse-grained particles by using a projection operator. Because the derived coarse-grained equation is based on microscopic description, it can be the basis for models of various coarse-grained simulations. We show that by substitution of random forces into fluctuating forces in the coarse-grained equation, the equations for Brownian dynamics and dissi...

the increasing use of nitrogen fertilizers due to high dynamics of nitrate in the soil would be a serious threat to groundwater, and therefore, to thuman health. this study is aimed to investigate the disperdivity values of nitrate in the coarse, medium and fine sandy soils in the short travel distance of 20, 40 and 80 cm in vitro using the hydrus-1d model. for this purpose, pure potassium nitr...

Maize and solvent extracted soybean meal (SBM) were ground through a 2 or 3 mm screen, resulting in “fine” and “coarse” material. The mean particle sizes of fine and coarse feed were 0.62 vs. 0.96 mm (maize) and 0.63 vs. 1.01 mm (SBM). Maize or SBM of either particle size was included in experimental diets at two different levels at the expense of maize starch. Three week old broilers had free ...

coarse product in the underflow. It is well known that injecting water in the conical part of the cyclone reduces the fine particle fraction in the underflow. This paper presents a mathematical model that simulates the water injection in the conical component. The model accounts for the fluid flow and the particle motion. Particle interaction, due to hindered settling caused by increased densit...

The microphase separation of hydrated perfluorinated sulfonic acid membrane Nafion was investigated using Dissipative Particle Dynamics (DPD). The nafion as a polymer was modelled by connecting coarse grained beads which corresponds to the hydrophobic backbone of polytetrafluoroethylene and perfluorinated side chains terminated by hydrophilic end particles of sulfonic acid groups [1, 2]. Each f...

aeolian process and subsequently soil erosion are key factors in dryland environments. such phenomena are related not only to geoecological factors (lithology, topography, and climatology) but also to land-use and plant cover changes. formation of new sand dunes in damghan explains the development of human activities over the past. the aim of this study is to explain the land use changes and th...

An experiment was conducted to determine the effects of soybean meal (SBM) particle size on broiler performance, particularly P utilization. This experiment utilized a 2 x 2 x 2 factorial design with the following variables: SBM particle size, P level, and diet type, either corn-SBM or semipurified. SBM was obtained from a processing plant before (geometric mean diameter 1,239 microm) and after...