15,014 research outputs found
Evaluating Cartogram Effectiveness
Cartograms are maps in which areas of geographic regions (countries, states)
appear in proportion to some variable of interest (population, income).
Cartograms are popular visualizations for geo-referenced data that have been
used for over a century and that make it possible to gain insight into patterns
and trends in the world around us. Despite the popularity of cartograms and the
large number of cartogram types, there are few studies evaluating the
effectiveness of cartograms in conveying information. Based on a recent task
taxonomy for cartograms, we evaluate four major different types of cartograms:
contiguous, non-contiguous, rectangular, and Dorling cartograms. Specifically,
we evaluate the effectiveness of these cartograms by quantitative performance
analysis, as well as by subjective preferences. We analyze the results of our
study in the context of some prevailing assumptions in the literature of
cartography and cognitive science. Finally, we make recommendations for the use
of different types of cartograms for different tasks and settings
An Efficient Approach for Generalized Load Balancing in Multipath Packet Switched Networks
This paper is a quantitative analysis on packet switched network with a view
to generalize load balancing and determination of appropriate routing algorithm
in multipath environment. Several routing algorithms have been introduced for
routing of packets from source to destination. Some of them route packets
accurately with increased workload and some of them drastically cut down the
workload. A few of them can find out a minimum workload deviation for both UDP
and TCP packets. We simulated these approaches in a well defined simulator,
analyzed and evaluated their performance. After expanding our analysis with
varying weights and number of paths we found that the recently proposed routing
algorithm Mixed Weighted Fair Routing (MWFR) outperforms the existing routing
algorithms by reducing the routing and network overhead and saving the scarce
bandwidth as well as CPU consumption for packet switching networks.Comment: 12 Pages, IJCNC Journal 201
Thermal conductivity and diffusion-mediated localization in Fe_{1-x}Cr_{x} Alloys
We apply a new Kubo-Greenwood type formula combined with a generalized
Feynman diagram- matic technique to report a first principles calculation of
the thermal transport properties of disordered Fe_{1-x}Cr_{x} alloys. The
diagrammatic approach simplifies the inclusion of disorder-induced scattering
effects on the two particle correlation functions and hence renormalizes the
heat current operator to calculate configuration averaged lattice thermal
conductivity and diffusivity. The thermal conductivity K(T) in the present case
shows an approximate quadratic T-dependence in the low temperature regime (T <
20 K), which subsequently rises smoothly to a T-independent saturated value at
high T . A numerical estimate of mobility edge from the thermal diffusivity
data yields the fraction of localized states. It is concluded that the complex
disorder scattering processes, in force-constant dominated disorder alloys such
as Fe-Cr, tend to localize the vibrational modes quite significantly.Comment: 5 pages, 5 figure
Constraints on holographic dark energy models using the differential ages of passively evolving galaxies
Using the absolute ages of passively evolving galaxies observed at different
redshifts, one can obtain the differential ages, the derivative of redshift
with respect to the cosmic time (i.e. ). Thus, the
Hubble parameter can be measured through the relation . By comparing the measured Hubble parameter at different
redshifts with the theoretical one containing free cosmological parameters, one
can constrain current cosmological models. In this paper, we use this method to
present the constraint on a spatially flat Friedman-Robert-Walker Universe with
a matter component and a holographic dark energy component, in which the
parameter plays a significant role in this dark energy model. Firstly we
consider three fixed values of =0.6, 1.0 and 1.4 in the fitting of data. If
we set free, the best fitting values are , ,
. It is shown that the holographic dark energy behaves like a
quintom-type at the level. This result is consistent with some other
independent cosmological constrains, which imply that is favored. We
also test the results derived from the differential ages using another
independent method based on the lookback time to galaxy clusters and the age of
the universe. It shows that our results are reliable.Comment: 18 pages including 7 figures and 1 tables. Final version for
publication in Modern Physics Letters A (MPLA)[minor revision to match the
appear version
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