4,113 research outputs found
Dynamic photoconductive gain effect in shallow-etched AlGaAs/GaAs quantum wires
We report on a dynamic photoconductive gain effect in quantum wires which are
lithographically fabricated in an AlGaAs/GaAs quantum well via a shallow-etch
technique. The effect allows resolving the one-dimensional subbands of the
quantum wires as maxima in the photoresponse across the quantum wires. We
interpret the results by optically induced holes in the valence band of the
quantum well which shift the chemical potential of the quantum wire. The
non-linear current-voltage characteristics of the quantum wires also allow
detecting the photoresponse effect of excess charge carriers in the conduction
band of the quantum well. The dynamics of the photoconductive gain are limited
by the recombination time of both electrons and holes
Start-up inertia as an origin for heterogeneous flow
For quite some time non-monotonic flow curve was thought to be a requirement
for shear banded flows in complex fluids. Thus, in simple yield stress fluids
shear banding was considered to be absent. Recent spatially resolved
rheological experiments have found simple yield stress fluids to exhibit shear
banded flow profiles. One proposed mechanism for the initiation of such
transient shear banding process has been a small stress heterogeneity rising
from the experimental device geometry. Here, using Computational Fluid Dynamics
methods, we show that transient shear banding can be initialized even under
homogeneous stress conditions by the fluid start-up inertia, and that such
mechanism indeed is present in realistic experimental conditions
Lipid contaminants: Polypropylene apparatus and vacuum pumps
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141137/1/lipd0192.pd
Palindromic complexity of trees
We consider finite trees with edges labeled by letters on a finite alphabet
. Each pair of nodes defines a unique labeled path whose trace is a
word of the free monoid . The set of all such words defines the
language of the tree. In this paper, we investigate the palindromic complexity
of trees and provide hints for an upper bound on the number of distinct
palindromes in the language of a tree.Comment: Submitted to the conference DLT201
Recurrence in 2D Inviscid Channel Flow
I will prove a recurrence theorem which says that any () solution
to the 2D inviscid channel flow returns repeatedly to an arbitrarily small
neighborhood. Periodic boundary condition is imposed along the
stream-wise direction. The result is an extension of an early result of the
author [Li, 09] on 2D Euler equation under periodic boundary conditions along
both directions
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