3,593 research outputs found
Radio continuum and far-infrared emission of spiral galaxies: Implications of correlations
Researchers present a study extending the correlation seen between radio continuum and far-infrared emissions from spiral galaxies to a lower frequency of 408 MHz and also as a function of radio spectral index. The tight correlation seen between the two luminosities is then used to constrain several parameters governing the emissions such as the changes in star formation rate and mass function, frequency of supernovae that are parents of the interstellar electrons and factors governing synchrotron radio emission
Write Channel Model for Bit-Patterned Media Recording
We propose a new write channel model for bit-patterned media recording that
reflects the data dependence of write synchronization errors. It is shown that
this model accommodates both substitution-like errors and insertion-deletion
errors whose statistics are determined by an underlying channel state process.
We study information theoretic properties of the write channel model, including
the capacity, symmetric information rate, Markov-1 rate and the zero-error
capacity.Comment: 11 pages, 12 figures, journa
Magnetic field effects on and the pseudogap onset temperature in cuprate superconductors
We study the sensitivity of and the pseudogap onset temperature,
, to low fields, , for cuprate superconductors, using a BCS-based
approach extended to arbitrary coupling. We find that and , which
are of the same superconducting origin, have very different dependences.
The small coherence length makes rather insensitive to the field.
However, the presence of the pseudogap at makes more sensitive to
. Our results for the coherence length fit well with existing
experiments. We predict that very near the insulator will rapidly
increase.Comment: 4 pages, 1 figure, contribution to the PPHMF-IV conference, Oct. 200
Two-Hop Routing with Traffic-Differentiation for QoS Guarantee in Wireless Sensor Networks
This paper proposes a Traffic-Differentiated Two-Hop Routing protocol for
Quality of Service (QoS) in Wireless Sensor Networks (WSNs). It targets WSN
applications having different types of data traffic with several priorities.
The protocol achieves to increase Packet Reception Ratio (PRR) and reduce
end-to-end delay while considering multi-queue priority policy, two-hop
neighborhood information, link reliability and power efficiency. The protocol
is modular and utilizes effective methods for estimating the link metrics.
Numerical results show that the proposed protocol is a feasible solution to
addresses QoS service differenti- ation for traffic with different priorities.Comment: 13 page
Deep Reinforcement Learning for Concentric Tube Robot Control with a Goal-Based Curriculum
Concentric Tube Robots (CTRs), a type of continuum robot, are a collection of concentric, pre-curved tubes
composed of super elastic nickel titanium alloy. CTRs can
bend and twist from the interactions between neighboring tubes
causing the kinematics and therefore control of the end-effector
to be very challenging to model. In this paper, we develop a
control scheme for a CTR end-effector in Cartesian space with
no prior kinematic model using a deep reinforcement learning
(DRL) approach with a goal-based curriculum reward strategy.
We explore the use of curricula by changing the goal tolerance
through training with constant, linear and exponential decay
functions. Also, relative and absolute joint representations
as a way of improving training convergence are explored.
Quantitative comparisons for combinations of curricula and
joint representations are performed and the exponential decay
relative approach is used for training a robust policy in a
noise-induced simulation environment. Compared to a previous
DRL approach, our new method reduces training time and
employs a more complex simulation environment. We report
mean Cartesian errors of 1.29 mm and a success rate of 0.93
with a relative decay curriculum. In path following, we report
mean errors of 1.37 mm in a noise-induced path following task.
Albeit in simulation, these results indicate the promise of using
DRL in model free control of continuum robots and CTRs in
particular
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