1,649 research outputs found
Book Review: New Age Globalization: Meaning and Metaphor by Aqueil Ahmad
New Age Globalization examines interdependent and interconnected global society in terms of its structure, including both functional and process characteristics, with an underlying concern for global consciousness resulting in global social change for human welfare. The theoretical framework provides for analysis of history, culture, economics, demographics, political systems, conflicts, knowledge, and religions of regions throughout the world. This is a well-researched book with information on complex topics for the global researcher, corporate planning executive, human resource manager, and educator, among others seeking to understand social and organizational systems in our global world
Navier-Stokes computations for circulation control airfoils
Navier-Stokes computations of subsonic to transonic flow past airfoils with augmented lift due to rearward jet blowing over a curved trailing edge are presented. The approach uses a spiral grid topology. Solutions are obtained using a Navier-Stokes code which employs an implicit finite difference method, an algebraic turbulence model, and developments which improve stability, convergence, and accuracy. Results are compared against experiments for no jet blowing and moderate jet pressures and demonstrate the capability to compute these complicated flows
Persistence of Randomly Coupled Fluctuating Interfaces
We study the persistence properties in a simple model of two coupled
interfaces characterized by heights h_1 and h_2 respectively, each growing over
a d-dimensional substrate. The first interface evolves independently of the
second and can correspond to any generic growing interface, e.g., of the
Edwards-Wilkinson or of the Kardar-Parisi-Zhang variety. The evolution of h_2,
however, is coupled to h_1 via a quenched random velocity field. In the limit
d\to 0, our model reduces to the Matheron-de Marsily model in two dimensions.
For d=1, our model describes a Rouse polymer chain in two dimensions advected
by a transverse velocity field. We show analytically that after a long waiting
time t_0\to \infty, the stochastic process h_2, at a fixed point in space but
as a function of time, becomes a fractional Brownian motion with a Hurst
exponent, H_2=1-\beta_1/2, where \beta_1 is the growth exponent characterizing
the first interface. The associated persistence exponent is shown to be
\theta_s^2=1-H_2=\beta_1/2. These analytical results are verified by numerical
simulations.Comment: 15 pages, 3 .eps figures include
Nonequilibrium Cotunneling through a Three-Level Quantum Dot
We calculate the nonlinear cotunneling conductance through a quantum dot with
3 electrons occupying the three highest lying energy levels. Starting from a
3-orbital Anderson model, we apply a generalized Schrieffer-Wolff
transformation to derive an effective Kondo model for the system. Within this
model we calculate the nonequilibrium occupation numbers and the corresponding
cotunneling current to leading order in the exchange couplings. We identify the
inelastic cotunneling thresholds and their splittings with applied magnetic
field, and make a qualitative comparison to recent experimental data on carbon
nanotube and InAs quantum-wire quantum dots. Further predictions of the model
like cascade resonances and a magnetic-field dependence of the orbital level
splitting are not yet observed but within reach of recent experimental work on
carbon nanotube and InAs nanowire quantum dots.Comment: 12 pages, 13 figure
Superconductivity-enhanced bias spectroscopy in carbon nanotube quantum dots
We study low-temperature transport through carbon nanotube quantum dots in
the Coulomb blockade regime coupled to niobium-based superconducting leads. We
observe pronounced conductance peaks at finite source-drain bias, which we
ascribe to elastic and inelastic cotunneling processes enhanced by the
coherence peaks in the density of states of the superconducting leads. The
inelastic cotunneling lines display a marked dependence on the applied gate
voltage which we relate to different tunneling-renormalizations of the two
subbands in the nanotube. Finally, we discuss the origin of an especially
pronounced sub-gap structure observed in every fourth Coulomb diamond
OVERFLOW Turbulence Modeling Resource Validation Results
Abstract:We exercise the computational fluid dynamics code OVERFLOW on sixteen turbulence model validation cases from the NASALangley Turbulence Model Resource web site. We give some information about the OVERFLOW options used to run these cases, and compare OVERFLOW results with results from other codes and with experiment. The goal is turbulence model validation for OVERFLOW
Synchronization Landscapes in Small-World-Connected Computer Networks
Motivated by a synchronization problem in distributed computing we studied a
simple growth model on regular and small-world networks, embedded in one and
two-dimensions. We find that the synchronization landscape (corresponding to
the progress of the individual processors) exhibits Kardar-Parisi-Zhang-like
kinetic roughening on regular networks with short-range communication links.
Although the processors, on average, progress at a nonzero rate, their spread
(the width of the synchronization landscape) diverges with the number of nodes
(desynchronized state) hindering efficient data management. When random
communication links are added on top of the one and two-dimensional regular
networks (resulting in a small-world network), large fluctuations in the
synchronization landscape are suppressed and the width approaches a finite
value in the large system-size limit (synchronized state). In the resulting
synchronization scheme, the processors make close-to-uniform progress with a
nonzero rate without global intervention. We obtain our results by ``simulating
the simulations", based on the exact algorithmic rules, supported by
coarse-grained arguments.Comment: 20 pages, 22 figure
Childhood motor performance is increased by participation in organized sport: the CHAMPS Study-DK
Evidence suggests that motor performance in children is declining globally. We tested whether participation in organized sport is associated with motor performance, and estimate the effect of 30 months participation in organized sport on motor performance. Study participants were 1067 primary school students, enrolled in the Danish Childhood Health, Activity, and Motor Performance School study. Participation in organized sport was reported via text messaging. Coordination-related motor performance composite, fitness-related motor performance composite, and total motor performance composite were calculated. Data were analyzed using Generalized Estimating Equations. Participation in organized sport was positively associated with motor performance (all composites) in models that did and did not control for baseline motor performance. For models that did not control for baseline motor performance, this equated to 2–6% increases in motor performance per weekly sport session; for models that did control for baseline motor performance, this equated to 1–5% increases in motor performance per weekly sport session. Positive associations between participation in organized sport and motor performance identify participation in organized sport as a way to improve motor performance in children. These results might provide the basis to determine whether participation in organized sport could be beneficial for children with developmental movement disorders
Superconductivity enhanced conductance fluctuations in few layer graphene nanoribbons
We investigate the mesoscopic disorder induced rms conductance variance
in a few layer graphene nanoribbon (FGNR) contacted by two
superconducting (S) Ti/Al contacts. By sweeping the back-gate voltage, we
observe pronounced conductance fluctuations superimposed on a linear background
of the two terminal conductance G. The linear gate-voltage induced response can
be modeled by a set of inter-layer and intra-layer capacitances.
depends on temperature T and source-drain voltage .
increases with decreasing T and . When lowering , a
pronounced cross-over at a voltage corresponding to the superconducting energy
gap is observed. For |V_{sd}|\ltequiv \Delta the fluctuations are
markedly enhanced. Expressed in the conductance variance of one
graphene-superconducutor (G-S) interface, values of 0.58 e^2/h are obtained at
the base temperature of 230 mK. The conductance variance in the sub-gap region
are larger by up to a factor of 1.4-1.8 compared to the normal state. The
observed strong enhancement is due to phase coherent charge transfer caused by
Andreev reflection at the nanoribbon-superconductor interface.Comment: 15 pages, 5 figure
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