21,701 research outputs found
Nutrient requirements and other factors involved in the culture of human kidney cells on microcarrier beads
The culture of human kidney cells on microcarrier beads in the Bioprocessing Laboratory at the Johnson Space Center is described. These were the first series of studies performed before and during 1983 to determine optimum conditions, including medium type, bead type and density. The composition of several medium types and the molecular weights of some common culture medium supplements and cellular proteins are included. The microgravity cell-to-bead attachment experiment performed on Space Transportation System Flight 8 is described
Development of small bore, high speed tapered roller bearing
The performance of four rolling bearing configurations for use on the input pinion shaft of a proposed commercial helicopter transmission was evaluated. The performance characteristics of a high speed tapered roller bearing operating under conditions comparable to those existing at this input pinion shaft were defined. The tapered roller bearing shaft support configuration was developed for the gearbox using commercially available bearing designings. The configuration was optimized and interactive thermomechanically system analyzed. Automotive pinion quality tapered roller bearings were found to be reliable under load and speed conditions in excess of those anticipated in the helicopter transmission. However, it is indicated that the elastohydrodynamic lubricant films are inadequate
Mach-Zehnder optical configuration with Brewster window and two quarter-wave plates
Configuration is improvement because of the following: It provides higher efficiency. It reduces or eliminates feedthrough of untranslated local oscillator, which would produce a beat signal at shifted frequency of translator. When used without translator and with low-power detector, telescope secondary mirror reflects portion of output to local oscillator
Effective transport barriers in nontwist systems
In fluids and plasmas with zonal flow reversed shear, a peculiar kind of transport barrier appears in the shearless region, one that is associated with a proper route of transition to chaos. These barriers have been identified in symplectic nontwist maps that model such zonal flows. We use the so-called standard nontwist map, a paradigmatic example of nontwist systems, to analyze the parameter dependence of the transport through a broken shearless barrier. On varying a proper control parameter, we identify the onset of structures with high stickiness that give rise to an effective barrier near the broken shearless curve. Moreover, we show how these stickiness structures, and the concomitant transport reduction in the shearless region, are determined by a homoclinic tangle of the remaining dominant twin island chains. We use the finite-time rotation number, a recently proposed diagnostic, to identify transport barriers that separate different regions of stickiness. The identified barriers are comparable to those obtained by using finite-time Lyapunov exponents.FAPESPCNPqCAPESMCT/CNEN (Rede Nacional de Fusao)Fundacao AraucariaUS Department of Energy DE-FG05-80ET-53088Physic
Internal wave pressure, velocity, and energy flux from density perturbations
Determination of energy transport is crucial for understanding the energy
budget and fluid circulation in density varying fluids such as the ocean and
the atmosphere. However, it is rarely possible to determine the energy flux
field , which requires simultaneous measurements of
the pressure and velocity perturbation fields, and . We present
a method for obtaining the instantaneous from density
perturbations alone: a Green's function-based calculation yields , and
is obtained by integrating the continuity equation and the
incompressibility condition. We validate our method with results from
Navier-Stokes simulations: the Green's function method is applied to the
density perturbation field from the simulations, and the result for
is found to agree typically to within with
computed directly using and from the Navier-Stokes
simulation. We also apply the Green's function method to density perturbation
data from laboratory schlieren measurements of internal waves in a stratified
fluid, and the result for agrees to within with results from
Navier-Stokes simulations. Our method for determining the instantaneous
velocity, pressure, and energy flux fields applies to any system described by a
linear approximation of the density perturbation field, e.g., to small
amplitude lee waves and propagating vertical modes. The method can be applied
using our Matlab graphical user interface EnergyFlux
Моделі термомеханіки багатокомпонентних деформівних твердих тіл
Зроблено короткий огляд і проаналізовано особливості теорій, що описують термомеханічну поведінку багатокомпонентних деформівних твердих тіл, зокрема, гомогенних твердих сумішей. Окремо виділено моделі для дослідження взаємозв’язаних механічних, теплових, дифузійних та електромагнітних процесів у тілах різної електропровідності та здатності до поляризації й намагнічення.A brief review and analysis of theories that describe the thermomechanical behavior of multicomponent deformable solids, in particular of homogeneous hard mixtures, have been presented. Also, the models for investigation of coupled electromagnetic, mechanical, thermal and diffusive processes in solids of various electric conductivity as well as abilities to polarization and magnetization are reviewed.Сделан краткий обзор и проанализированы особенности теорий, описывающих термомеханическое поведение многокомпонентных деформируемых твердых тел, в частности, гомогенных твердых смесей. Отдельно выделены модели для исследования механических, тепловых и диффузионных процессов во взаимосвязи с электромагнитными в поляризирующихся и намагничивающихся электропроводных телах
Chern-Simons Reduction and non-Abelian Fluid Mechanics
We propose a non-Abelian generalization of the Clebsch parameterization for a
vector in three dimensions. The construction is based on a group-theoretical
reduction of the Chern-Simons form on a symmetric space. The formalism is then
used to give a canonical (symplectic) discussion of non-Abelian fluid
mechanics, analogous to the way the Abelian Clebsch parameterization allows a
canonical description of conventional fluid mechanics.Comment: 12 pages, REVTeX; revised for publication in Phys Rev D; email to
[email protected]
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