15,016 research outputs found
Bivaraiate Generalized Baskakov Kantorovich Operators
This paper is in continuation of our work in \cite{PNM}, wherein we
introduced generalized Baskakov Kantorovich operators and
established some approximation properties e.g. local approximation, weighted
approximation, simultaneous approximation and statistical convergence.
Also, we discussed the rate of convergence for functions having a derivative
coinciding a.e. with a function of bounded variation. The purpose of this paper
is to study the bivariate extension of the operators and discuss
results on the degree of approximation, Voronovskaja type theorems and their
first order derivatives in polynomial weighted spaces.Comment: 1
Generalized Baskakov Kantorovich Operators
In this paper, we construct generalized Baskakov Kantorovich operators. We
establish some direct results and then study weighted approximation,
simultaneous approximation and statistical convergence properties for these
operators. Finally, we obtain the rate of convergence for functions having a
derivative coinciding almost everywhere with a function of bounded variation
for these operator
Circular orbit spacecraft control at the L4 point using Lyapunov functions
The objective of this work is to demonstrate the utility of Lyapunov
functions in control synthesis for the purpose of maintaining and stabilizing a
spacecraft in a circular orbit around the L4 point in the circular restricted
three body problem (CRTBP). Incorporating the requirements of a fixed radius
orbit and a desired angular momentum, a Lyapunov function is constructed and
the requisite analysis is performed to obtain a controller. Asymptotic
stability is proved in a defined region around the L4 point using LaSalle's
principle.Comment: Accepted for presentation at European Control Conference 201
Approximation by complex Szasz-Durrmeyer-Chlodowsky operators in compact disks
In the present article, we deal with the overconvergence of the
Sz?asz-Durrmeyer-Chlodowsky operators. Here we study the approximation
properties e.g. upper estimates, Voronovskaja type result for these operators
attached to analytic functions in compact disks. Also, we discuss the exact
order in simultaneous approximation by these operators and its derivatives and
the asymptotic result with quantitative upper estimate. In such a way, we put
in evidence the overconvergence phenomenon for the Sz?asz-Durrmeyer-Chlodowsky
operators, namely the extensions of approximation properties with exact
quantitative estimates and orders of these convergencies to sets in the complex
plane that contain the interval [0,\infty)
Better approximation of functions by genuine Bernstein-Durrmeyer type operators
The main object of this paper is to construct a new genuine
Bernstein-Durrmeyer type operators which have better features than the
classical one. Some direct estimates for the modified genuine
Bernstein-Durrmeyer operator by means of the first and second modulus of
continuity are given. An asymptotic formula for the new operator is proved.
Finally, some numerical examples with illustrative graphics have been added to
validate the theoretical results and also compare the rate of convergence
Constraining the symmetry energy content of nuclear matter from nuclear masses: a covariance analysis
Elements of nuclear symmetry energy evaluated from different energy density
functionals parametrized by fitting selective bulk properties of few
representative nuclei are seen to vary widely. Those obtained from experimental
data on nuclear masses across the periodic table, however, show that they are
better constrained. A possible direction in reconciling this paradox may be
gleaned from comparison of results obtained from use of the binding energies in
the fitting protocol within a microscopic model with two sets of nuclei, one a
representative standard set and another where very highly asymmetric nuclei are
additionally included. A covariance analysis reveals that the additional
fitting protocol reduces the uncertainties in the nuclear symmetry energy
coefficient, its slope parameter as well as the neutron-skin thickness in
Pb nucleus by . The central values of these entities are
also seen to be slightly reduced.Comment: 6 pages, 2 figures, Accepted in Physical Review
Hierarchical Cellular Structures in High-Capacity Cellular Communication Systems
In the prevailing cellular environment, it is important to provide the
resources for the fluctuating traffic demand exactly in the place and at the
time where and when they are needed. In this paper, we explored the ability of
hierarchical cellular structures with inter layer reuse to increase the
capacity of mobile communication network by applying total frequency hopping
(T-FH) and adaptive frequency allocation (AFA) as a strategy to reuse the macro
and micro cell resources without frequency planning in indoor pico cells [11].
The practical aspects for designing macro- micro cellular overlays in the
existing big urban areas are also explained [4]. Femto cells are inducted in
macro / micro / pico cells hierarchical structure to achieve the required QoS
cost effectively.Comment: 7 pages, 8 figures, International Journa
Lower Limits on the Strengths of Gamma Ray Lines from WIMP Dark Matter Annihilation
We study the spectra of gamma ray signals that arise from dark matter
annihilation in the universe. We focus on the large class of theories where the
photon spectrum includes both continuum spectrum of gamma rays that arise from
annihilation into Standard Model states at tree level, as well as monochromatic
gamma rays arising from annihilation directly into two photons at the one loop
level. In this class of theories we obtain lower bounds on the ratio of the
strength of the gamma ray line relative to the gamma ray continuum as a
function of the dark matter mass and spin. These limits are obtained from the
unitarity relation between the tree level amplitude of the primary annihilation
channel and the imaginary part of the loop level amplitude for annihilation
directly into photons, with the primary decay products running in the loop.
These results are exact in the limit that dark matter annihilation is
exclusively to a single Standard Model species, occurs through the lowest
partial wave and respects CP. Away from this limit the bounds are approximate.
Our conclusions agree with the known results in the literature in the case of
the Minimal Supersymmetric Standard Model (MSSM). We use the Fermi-LAT
observations to translate these limits into upper bounds on the dark matter
annihilation cross section into any specific Standard Model state.Comment: 11 pages, 3 figures, 1 table ;v2: 14 pages, 6 figures, 2 tables,
added discussion of effects of the continuum spectrum in the neighborhood of
the line, matches version in PR
Reassessing nuclear matter incompressibility and its density dependence
Experimental giant monopole resonance energies are now known to constrain
nuclear incompressibility of symmetric nuclear matter and its density slope
at a particular value of sub-saturation density, the crossing density
. Consistent with these constraints, we propose a reasonable way to
construct a plausible equation of state of symmetric nuclear matter in a broad
density region around the saturation density . Help of two additional
empirical inputs, the value of and that of the energy per nucleon
are needed. The value of comes out to be MeV.Comment: 5 page including 4 figures. Phys. Rev. C (in press
Determining the density content of symmetry energy and neutron skin: an empirical approach
The density dependence of nuclear symmetry energy remains poorly constrained.
Starting from precise empirical values of the nuclear volume and surface
symmetry energy coefficients and the nuclear saturation density, we show how in
the ambit of microscopic calculations with different energy density
functionals, the value of the symmetry energy slope parameter alongwith
that for neutron skin can be put in tighter bounds. The value of is found
to be = 645 MeV. For Pb, the neutron skin thickness comes out
to be 0.188 0.014 fm. Knowing , the method can be applied to predict
neutron skins of other nuclei.Comment: 5 pages, Phys. Rev. Lett. (accpeted
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