11,349 research outputs found
Decision Maker using Coupled Incompressible-Fluid Cylinders
The multi-armed bandit problem (MBP) is the problem of finding, as accurately
and quickly as possible, the most profitable option from a set of options that
gives stochastic rewards by referring to past experiences. Inspired by
fluctuated movements of a rigid body in a tug-of-war game, we formulated a
unique search algorithm that we call the `tug-of-war (TOW) dynamics' for
solving the MBP efficiently. The cognitive medium access, which refers to
multi-user channel allocations in cognitive radio, can be interpreted as the
competitive multi-armed bandit problem (CMBP); the problem is to determine the
optimal strategy for allocating channels to users which yields maximum total
rewards gained by all users. Here we show that it is possible to construct a
physical device for solving the CMBP, which we call the `TOW Bombe', by
exploiting the TOW dynamics existed in coupled incompressible-fluid cylinders.
This analog computing device achieves the `socially-maximum' resource
allocation that maximizes the total rewards in cognitive medium access without
paying a huge computational cost that grows exponentially as a function of the
problem size.Comment: 5 pages, 5 figures, Waseda AICS Symposium and the 14th Slovenia-Japan
Seminar, Waseda University, Tokyo, 24-26 October 2014. in Special Issue of
ASTE: Advances in Science, Technology and Environmentology (2015
Randomness Evaluation and Hardware Implementation of Nonadditive CA-Based Stream Cipher
We shall review the cellular automaton(CA)-based pseudorandom-number
generators (PRNGs), and show that one of these PRNGs can generate high-quality
random numbers which can pass all of the statistical tests provided by the
National Institute of Standards and Technology (NIST). A CA is suitable for
hardware implementation. We demonstrate that the CA-based stream cipher, which
is implemented in the field-programmable gate arrays (FPGA), has a high
encryption speed in a real-time video encryption and decryption system.Comment: to be published in Journal of Signal Processin
The Painlev\'e Test of Higher Dimensional KdV Equation
We argue the integrability of the generalized KdV(GKdV) equation using the
Painlev\'e test. For dimensional space, GKdV equation passes the
Painlev\'e test but does not for dimensional space. We also apply
the Ablowitz-Ramani-Segur's conjecture to the GKdV equation in order to
complement the Painlev\'e test.Comment: 7 pages, LaTe
Incompressible limit of the compressible magnetohydrodynamic equations with periodic boundary conditions
This paper is concerned with the incompressible limit of the compressible
magnetohydrodynamic equations with periodic boundary conditions. It is
rigorously shown that the weak solutions of the compressible
magnetohydrodynamic equations converge to the strong solution of the viscous or
inviscid incompressible magnetohydrodynamic equations as long as the latter
exists both for the well-prepared initial data and general initial data.
Furthermore, the convergence rates are also obtained in the case of the
well-prepared initial data.Comment: 28 page
Incompressible limit of the non-isentropic ideal magnetohydrodynamic equations
We study the incompressible limit of the compressible non-isentropic ideal
magnetohydrodynamic equations with general initial data in the whole space
(). We first establish the existence of classic solutions
on a time interval independent of the Mach number. Then, by deriving uniform a
priori estimates, we obtain the convergence of the solution to that of the
incompressible magnetohydrodynamic equations as the Mach number tends to zero.Comment: 18pages, submitted. arXiv admin note: substantial text overlap with
arXiv:1111.292
Self-sustaining oscillations of a falling sphere through Johnson-Segalman fluids
We confirm numerically that the Johnson-Segalman model is able to reproduce
the continual oscillations of the falling sphere observed in some viscoelastic
models. The empirical choice of parameters used in the Johnson-Segalman model
is from the ones that show the non-monotone stress-strain relation of the
steady shear flows of the model. The carefully chosen parameters yield
continual, self-sustaining, (ir)regular and periodic oscillations of the speed
for the falling sphere through the Johnson-Segalman fluids. In particular, our
simulations reproduce the phenomena: the falling sphere settles slower and
slower until a certain point at which the sphere suddenly accelerates and this
pattern is repeated continually
Controlling decoherence speed limit of a single impurity atom in a Bose-Einstein-condensate reservoir
We study the decoherence speed limit (DSL) of a single impurity atom immersed
in a Bose-Einsteincondensed (BEC) reservoir when the impurity atom is in a
double-well potential. We demonstrate how the DSL of the impurity atom can be
manipulated by engineering the BEC reservoir and the impurity potential within
experimentally realistic limits. We show that the DSL can be controlled by
changing key parameters such as the condensate scattering length, the effective
dimension of the BEC reservoir, and the spatial configuration of the
double-well potential imposed on the impurity. We uncover the physical
mechanisms of controlling the DSL at root of the spectral density of the BEC
reservoir.Comment: 8 pages, 8 figure
Hierarchy of Higher Dimensional Integrable System
Integrable equations in () dimensions have their own higher order
integrable equations, like the KdV, mKdV and NLS hierarchies etc. In this paper
we consider whether integrable equations in () dimensions have also the
analogous hierarchies to those in () dimensions. Explicitly is discussed
the Bogoyavlenskii-Schiff(BS) equation. For the BS hierarchy, there appears an
ambiguity in the Painlev\'e test. Nevertheless, it may be concluded that the BS
hierarchy is integrable.Comment: 10 pages, uses ioplppt.st
Efficient Decision-Making by Volume-Conserving Physical Object
We demonstrate that any physical object, as long as its volume is conserved
when coupled with suitable operations, provides a sophisticated decision-making
capability. We consider the problem of finding, as accurately and quickly as
possible, the most profitable option from a set of options that gives
stochastic rewards. These decisions are made as dictated by a physical object,
which is moved in a manner similar to the fluctuations of a rigid body in a
tug-of-war game. Our analytical calculations validate statistical reasons why
our method exhibits higher efficiency than conventional algorithms.Comment: 5 pages, 3 figure
Harnessing Natural Fluctuations: Analogue Computer for Efficient Socially Maximal Decision Making
Each individual handles many tasks of finding the most profitable option from
a set of options that stochastically provide rewards. Our society comprises a
collection of such individuals, and the society is expected to maximise the
total rewards, while the individuals compete for common rewards. Such
collective decision making is formulated as the `competitive multi-armed bandit
problem (CBP)', requiring a huge computational cost. Herein, we demonstrate a
prototype of an analog computer that efficiently solves CBPs by exploiting the
physical dynamics of numerous fluids in coupled cylinders. This device enables
the maximisation of the total rewards for the society without paying the
conventionally required computational cost; this is because the fluids estimate
the reward probabilities of the options for the exploitation of past knowledge
and generate random fluctuations for the exploration of new knowledge. Our
results suggest that to optimise the social rewards, the utilisation of
fluid-derived natural fluctuations is more advantageous than applying
artificial external fluctuations. Our analog computing scheme is expected to
trigger further studies for harnessing the huge computational power of natural
phenomena for resolving a wide variety of complex problems in modern
information society.Comment: 30 pages, 3 figure
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