1,152 research outputs found
Resolution of Veronese Embedding of plane curves
Let be a smooth (irreducible) curve of degree in .
Let be the Veronese embedding
and let denote the homogeneous ideal of on
. In this note we explicitly write down the minimal free
resolution of for $d\geq
Magic Melters' Have Geometrical Origin
Recent experimental reports bring out extreme size sensitivity in the heat
capacities of Gallium and Aluminum clusters. In the present work we report
results of our extensive {\it ab initio} molecular dynamical simulations on
Ga and Ga, the pair which has shown rather dramatic size
sensitivity. We trace the origin of this size sensitive heat capacities to the
relative order in their respective ground state geometries. Such an effect of
nature of the ground state on the characteristics of heat capacities is also
seen in case of small Gallium and Sodium clusters indicating that the observed
size sensitivity is a generic feature of small clusters.Comment: 4 pages, 6 figure
Finite temperature behavior of impurity doped Lithium cluster {\em viz} LiSn
We have carried out extensive isokinetic {\it ab initio} molecular dynamic
simulations to investigate the finite temperature properties of the impurity
doped cluster LiSn along with the host cluster Li. The data obtained
from about 20 temperatures and total simulation time of at least 3 ns is used
to extract thermodynamical quantities like canonical specific heat. We observe
a substantial charge transfer from all Li atoms to Sn which inturn weakens the
Li-Li bonds in LiSn compared to the bonds in Li. This weakening of
bonds changes the finite temperature behavior of LiSn significantly.
Firstly, LiSn becomes liquid-like around 250 K, a much lower temperature
than that of Li (~425 K). Secondly, an additional quasirotational
motion of lithium atoms appears at lower temperatures giving rise to a shoulder
around 50 K in the specific heat curve of LiSn. The peak in the specific
heat of Li is very broad and the specific heat does not show any premelting
features.Comment: 16 pages, 10 figures Submitted to J. Chem. Phy
A Trust-based Recruitment Framework for Multi-hop Social Participatory Sensing
The idea of social participatory sensing provides a substrate to benefit from
friendship relations in recruiting a critical mass of participants willing to
attend in a sensing campaign. However, the selection of suitable participants
who are trustable and provide high quality contributions is challenging. In
this paper, we propose a recruitment framework for social participatory
sensing. Our framework leverages multi-hop friendship relations to identify and
select suitable and trustworthy participants among friends or friends of
friends, and finds the most trustable paths to them. The framework also
includes a suggestion component which provides a cluster of suggested friends
along with the path to them, which can be further used for recruitment or
friendship establishment. Simulation results demonstrate the efficacy of our
proposed recruitment framework in terms of selecting a large number of
well-suited participants and providing contributions with high overall trust,
in comparison with one-hop recruitment architecture.Comment: accepted in DCOSS 201
Metallo-Anti-aromatic Al4Na4 and Al4Na3- compounds: A theoretical investigation
We propose a theoretical investigation in this paper to understand the
bonding and structural properties of neutral Al4Na4 and anion Al4Na3- clusters.
We show that the Al4 species in Al4Na4 and Al4Na3- clusters is a rectangular
planar structure with alternate pi-bonds and hence satisfying the basic
criteria for anti-aromaticity. We prove that the Al4Na4 and Al4Na3- clusters
are metallo-anti-aromatic compounds
Recharging of Flying Base Stations using Airborne RF Energy Sources
This paper presents a new method for recharging flying base stations, carried
by Unmanned Aerial Vehicles (UAVs), using wireless power transfer from
dedicated, airborne, Radio Frequency (RF) energy sources. In particular, we
study a system in which UAVs receive wireless power without being disrupted
from their regular trajectory. The optimal placement of the energy sources are
studied so as to maximize received power from the energy sources by the
receiver UAVs flying with a linear trajectory over a square area. We find that
for our studied scenario of two UAVs, if an even number of energy sources are
used, placing them in the optimal locations maximizes the total received power,
while achieving fairness among the UAVs. However, in the case of using an odd
number of energy sources, we can either maximize the total received power, or
achieve fairness, but not both at the same time. Numerical results show that
placing the energy sources at the suggested optimal locations results in
significant power gain compared to nonoptimal placements.Comment: 6 pages, 5 figures, conference pape
Structure, electronic properties and magnetic transition in manganese clusters
We systematically investigate the structural, electronic and magnetic
properties of Mn clusters ( 220) within the {\it ab-initio}
pseudopotential plane wave method using generalized gradient approximation for
the exchange-correlation energy. A new kind of icosahedral structural growth
has been predicted in the intermediate size range. Calculated magnetic moments
show an excellent agreement with the Stern-Gerlach experiment. A transition
from ferromagnetic to ferrimagnetic MnMn coupling takes place at 5 and
the ferrimagnetic states continue to be the ground states for the entire size
range. Possible presence of multiple isomers in the experimental beam has been
argued. No signature of non-metal to metal transition is observed in this size
range and the coordination dependence of electron localization is
discussed.Comment: 11 Pages and 9 Figures. Physical Review B (in press
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