17,140 research outputs found
On Match Lengths, Zero Entropy and Large Deviations - with Application to Sliding Window Lempel-Ziv Algorithm
The Sliding Window Lempel-Ziv (SWLZ) algorithm that makes use of recurrence
times and match lengths has been studied from various perspectives in
information theory literature. In this paper, we undertake a finer study of
these quantities under two different scenarios, i) \emph{zero entropy} sources
that are characterized by strong long-term memory, and ii) the processes with
weak memory as described through various mixing conditions.
For zero entropy sources, a general statement on match length is obtained. It
is used in the proof of almost sure optimality of Fixed Shift Variant of
Lempel-Ziv (FSLZ) and SWLZ algorithms given in literature. Through an example
of stationary and ergodic processes generated by an irrational rotation we
establish that for a window of size , a compression ratio given by
where depends on and approaches 1 as
, is obtained under the application of FSLZ and SWLZ
algorithms. Also, we give a general expression for the compression ratio for a
class of stationary and ergodic processes with zero entropy.
Next, we extend the study of Ornstein and Weiss on the asymptotic behavior of
the \emph{normalized} version of recurrence times and establish the \emph{large
deviation property} (LDP) for a class of mixing processes. Also, an estimator
of entropy based on recurrence times is proposed for which large deviation
principle is proved for sources satisfying similar mixing conditions.Comment: accepted to appear in IEEE Transactions on Information Theor
Study of effective interaction from single particle transfer reactions on f-p shell nuclei
The present study concentrates on the average effective two-body interaction
matrix elements being extracted, using sum-rule techniques, from transfer
reactions on target states having single orbital as well as two
orbitaloccupancy. This investigation deals with transfer reactions on f-p shell
nuclei involving (i) and transfer on target states using
Ca as inert core, and (ii) and transfer on states
using Ni as core.Comment: 12 pages, ptptex Subj-Classes: Nuclear Shell Structure
e-mail:[email protected]
Listen, Attend, and Walk: Neural Mapping of Navigational Instructions to Action Sequences
We propose a neural sequence-to-sequence model for direction following, a
task that is essential to realizing effective autonomous agents. Our
alignment-based encoder-decoder model with long short-term memory recurrent
neural networks (LSTM-RNN) translates natural language instructions to action
sequences based upon a representation of the observable world state. We
introduce a multi-level aligner that empowers our model to focus on sentence
"regions" salient to the current world state by using multiple abstractions of
the input sentence. In contrast to existing methods, our model uses no
specialized linguistic resources (e.g., parsers) or task-specific annotations
(e.g., seed lexicons). It is therefore generalizable, yet still achieves the
best results reported to-date on a benchmark single-sentence dataset and
competitive results for the limited-training multi-sentence setting. We analyze
our model through a series of ablations that elucidate the contributions of the
primary components of our model.Comment: To appear at AAAI 2016 (and an extended version of a NIPS 2015
Multimodal Machine Learning workshop paper
Effective two-body interactions in the s-d shell nuclei from sum rules equations in tranfer reactions
Average effective two-body interaction matrix elements in the s-d shell have
been extracted, from data on experimentally measured isospin centroids, by
combining the recently derived new sum rules equations for pick-up reactions
with similar known equations for stripping reactions performed on general
multishell target states. Using this combination of stripping and pick-up
equations, the average effective matrix elements for the shells, 1d^2_5/2,
2s^2_1/2 and 1d^2_3/2 respectively have been obtained. A new feature of the
present work is that the restriction imposed in earlier works on target states,
that it be populated only by active neutrons has now been abandoned.Comment: 12 pages, RevTeX, e-mail: [email protected]
Superconducting ceramics in the Bi1.5SrCaCu2O sub x system by melt quenching technique
Bi sub 1.5 SrCaCu sub 2 O sub x has been prepared in the glassy state by rapid quenching of the melt. The kinetics of crystallization of various phases in the glass have been evaluated by a variable heating rate differential scanning calorimetry method. The formation various phases on thermal treatments of the glass has been investigated by powder X-ray diffraction and electrical resistivity measurements. Heating at 450 C formed Bi sub 2 Sr sub 2 CuO sub 6, which disappeared on further heating at 765 C, where Bi sub 2 Sr sub 2 CaCu sub 2 O sub 8 formed. Prolonged heating at 845 C resulted in the formation of a small amount of a phase with T sub c onset of approx. 108 K, believed to be Bi sub 2 Sr sub 2 Ca sub 2 Cu sub 3 O sub 10. This specimen showed zero resistivity at 54 K. The glass ceramic approach could offer several advantages in the fabrication of the high-T sub c superconductors in desired practical shapes such as continuous fibers, wires, tapes, etc
- …