5,671 research outputs found
Self-Organization of Balanced Nodes in Random Networks with Transportation Bandwidths
We apply statistical physics to study the task of resource allocation in
random networks with limited bandwidths along the transportation links. The
mean-field approach is applicable when the connectivity is sufficiently high.
It allows us to derive the resource shortage of a node as a well-defined
function of its capacity. For networks with uniformly high connectivity, an
efficient profile of the allocated resources is obtained, which exhibits
features similar to the Maxwell construction. These results have good
agreements with simulations, where nodes self-organize to balance their
shortages, forming extensive clusters of nodes interconnected by unsaturated
links. The deviations from the mean-field analyses show that nodes are likely
to be rich in the locality of gifted neighbors. In scale-free networks, hubs
make sacrifice for enhanced balancing of nodes with low connectivity.Comment: 7 pages, 8 figure
Antipersistant Effects in the Dynamics of a Competing Population
We consider a population of agents competing for finite resources using
strategies based on two channels of signals. The model is applicable to
financial markets, ecosystems and computer networks. We find that the dynamics
of the system is determined by the correlation between the two channels. In
particular, occasional mismatches of the signals induce a series of transitions
among numerous attractors. Surprisingly, in contrast to the effects of noises
on dynamical systems normally resulting in a large number of attractors, the
number of attractors due to the mismatched signals remains finite. Both
simulations and analyses show that this can be explained by the antipersistent
nature of the dynamics. Antipersistence refers to the response of the system to
a given signal being opposite to that of the signal's previous occurrence, and
is a consequence of the competition of the agents to make minority decisions.
Thus, it is essential for stabilizing the dynamical systems.Comment: 4 pages, 6 figure
Cascades of Dynamical Transitions in an Adaptive Population
In an adaptive population which models financial markets and distributed
control, we consider how the dynamics depends on the diversity of the agents'
initial preferences of strategies. When the diversity decreases, more agents
tend to adapt their strategies together. This change in the environment results
in dynamical transitions from vanishing to non-vanishing step sizes. When the
diversity decreases further, we find a cascade of dynamical transitions for the
different signal dimensions, supported by good agreement between simulations
and theory. Besides, the signal of the largest step size at the steady state is
likely to be the initial signal.Comment: 4 pages, 8 figure
Models of Financial Markets with Extensive Participation Incentives
We consider models of financial markets in which all parties involved find
incentives to participate. Strategies are evaluated directly by their virtual
wealths. By tuning the price sensitivity and market impact, a phase diagram
with several attractor behaviors resembling those of real markets emerge,
reflecting the roles played by the arbitrageurs and trendsetters, and including
a phase with irregular price trends and positive sums. The positive-sumness of
the players' wealths provides participation incentives for them. Evolution and
the bid-ask spread provide mechanisms for the gain in wealth of both the
players and market-makers. New players survive in the market if the
evolutionary rate is sufficiently slow. We test the applicability of the model
on real Hang Seng Index data over 20 years. Comparisons with other models show
that our model has a superior average performance when applied to real
financial data.Comment: 17 pages, 16 figure
Flight Test Methodology for NASA Advanced Inlet Liner on 737MAX-7 Test Bed (Quiet Technology Demonstrator 3)
This paper describes the acoustic flight test results of an advanced nacelle inlet acoustic liner concept designed by NASA Langley, in a campaign called Quiet Technology Demonstrator 3 (QTD3). NASA has been developing multiple acoustic liner concepts to benefit acoustics with multiple-degrees of freedom (MDOF) honeycomb cavities, and lower the excrescence drag. Acoustic and drag performance were assessed at a lab-scale, flow duct level in 2016. Limitations of the lab-scale rig left open-ended questions regarding the in-flight acoustic performance. This led to a joint project to acquire acoustic flyover data with this new liner technology built into full scale inlet hardware containing the NASA MDOF Low Drag Liner. Boeing saw an opportunity to collect the acoustic flyover data on the 737 MAX-7 between certification tests at no impact to the overall program schedule, and successfully executed within the allotted time. The flight test methodology and the test configurations are detailed and the acoustic analysis is summarized in this paper. After the tone and broadband deltas associated with the inlet hardware were separated and evaluated, the result was a significant decrease in cumulative EPNL (Effective Perceived Noise Level)
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