4,373 research outputs found
Recommended from our members
Hereditariness, strongness and relationship between Brown-McCoy and Behrens radicals
In this paper we explore the properties of being hereditary and being strong among the radicals of associative rings, and prove certain results such as a relationship between Brown-McCoy and Behrens radicals
On the Positive Effect of Delay on the Rate of Convergence of a Class of Linear Time-Delayed Systems
This paper is a comprehensive study of a long observed phenomenon of increase
in the stability margin and so the rate of convergence of a class of linear
systems due to time delay. We use Lambert W function to determine (a) in what
systems the delay can lead to increase in the rate of convergence, (b) the
exact range of time delay for which the rate of convergence is greater than
that of the delay free system, and (c) an estimate on the value of the delay
that leads to the maximum rate of convergence. For the special case when the
system matrix eigenvalues are all negative real numbers, we expand our results
to show that the rate of convergence in the presence of delay depends only on
the eigenvalues with minimum and maximum real parts. Moreover, we determine the
exact value of the maximum rate of convergence and the corresponding maximizing
time delay. We demonstrate our results through a numerical example on the
practical application in accelerating an agreement algorithm for
networked~systems by use of a delayed feedback
On Robustness Analysis of a Dynamic Average Consensus Algorithm to Communication Delay
This paper studies the robustness of a dynamic average consensus algorithm to
communication delay over strongly connected and weight-balanced (SCWB)
digraphs. Under delay-free communication, the algorithm of interest achieves a
practical asymptotic tracking of the dynamic average of the time-varying
agents' reference signals. For this algorithm, in both its continuous-time and
discrete-time implementations, we characterize the admissible communication
delay range and study the effect of the delay on the rate of convergence and
the tracking error bound. Our study also includes establishing a relationship
between the admissible delay bound and the maximum degree of the SCWB digraphs.
We also show that for delays in the admissible bound, for static signals the
algorithms achieve perfect tracking. Moreover, when the interaction topology is
a connected undirected graph, we show that the discrete-time implementation is
guaranteed to tolerate at least one step delay. Simulations demonstrate our
results
Non-minimal Derivative Coupling Scalar Field and Bulk Viscous Dark Energy
Inspired by thermodynamical dissipative phenomena, we consider bulk viscosity
for dark fluid in a spatially flat two-component Universe. Our viscous dark
energy model represents Phantom crossing avoiding Big-Rip singularity. We
propose a non-minimal derivative coupling scalar field with zero potential
leading to accelerated expansion of Universe in the framework of bulk viscous
dark energy model. In this approach, coupling constant () is related to
viscosity coefficient () and energy density of dark energy at the
present time (). This coupling is bounded as and for leads to . To
perform robust analysis, we implement recent observational data sets including
Joint Light-curve Analysis (JLA) for SNIa, Gamma Ray Bursts (GRBs) for most
luminous astrophysical objects at high redshifts, Baryon Acoustic Oscillations
(BAO) from different surveys, Hubble parameter from HST project, {\it Planck}
data for CMB power spectrum and CMB Lensing. Joint analysis of
JLAGRBsBAOHST shows that ,
and at confidence interval.
{\it Planck} TT observation provides at
confidence limit for viscosity coefficient. Tension in Hubble parameter is
alleviated in this model. Cosmographic distance ratio indicates that current
observed data prefer to increase bulk viscosity. Finally, the competition
between Phantom and Quintessence behavior of viscous dark energy model can
accommodate cosmological old objects reported as a sign of age crisis in
CDM model.Comment: 21 pages and 18 figures, some typos in equations fixe
Brushes of flexible, semiflexible and rodlike diblock polyampholytes: Molecular dynamics simulation and scaling analysis
Planar brushes of flexible, semiflexible and rodlike diblock polyampholytes
are studied using molecular dynamics simulations and scaling analysis in a wide
range of the grafting density. Simulations show linear dependence of the
average thickness on the grafting density for all the brushes regardless of
their different equilibrium conformations and different flexibility of anchored
chains. Slopes of fitted lines to the average thickness of the brushes of
semiflexible and rodlike polyampholytes versus the grafting density are
approximately the same and differ considerably from that of the brush of
flexible chains. The average thickness of the brush of diblock polyampholytes
is also obtained as a function of the grafting density using a simple scaling
analysis which is in good agreement with the results of our simulations.Comment: 5 Figure
- …