1,169 research outputs found
Active Noise Control using Variable step-size Griffiths’ LMS (VGLMS) algorithm on Real-Time platform
This paper proposes implementation of Griffith’s Variable step-size algorithm for Active Noise Control (ANC) on
ADSP-TS201 EZ-Kit Lite. The dual computational units and
execution of up to four instructions per cycle which are special features over other processors are best utilized to generate an optimized code. The VGLMS provides improved secondary path estimation and computations involved are marginal as the same gradient is used for step-size computation and coefficient adaptation. The improved secondary path estimate, in turn improves the ANC performance. Further, variable step-size algorithm is used for the main-path to achieve faster convergence. Both for narrowband (fundamental and its harmonics) and broadband noise fields, for a duct the attenuation achieved is 25 dB and 15 dB respectively. The program execution time was only 1.25% for an input sampling rate of 1 KHz which indicates the utility of the special features of the processor considered. Further these features have enabled in bringing down the program memory requirement in the implementation of the algorithm
On the naturality of the Mathai-Quillen formula
We give an alternative proof for the Mathai-Quillen formula for a Thom form
using its natural behaviour with respect to fiberwise integration. We also
study this phenomenon in general context.Comment: 6 page
Intercomparison of Latent Heat Flux Estimates Based on Energy Balance Models
Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv
flatIGW - an inverse algorithm to compute the Density of States of lattice Self Avoiding Walks
We show that the Density of States (DoS) for lattice Self Avoiding Walks can
be estimated by using an inverse algorithm, called flatIGW, whose step-growth
rules are dynamically adjusted by requiring the energy histogram to be locally
flat. Here, the (attractive) energy associated with a configuration is taken to
be proportional to the number of non-bonded nearest neighbor pairs (contacts).
The energy histogram is able to explicitly direct the growth of a walk because
the step-growth rule of the Interacting Growth Walk \cite{IGW} samples the
available nearest neighbor sites according to the number of contacts they would
make. We have obtained the complex Fisher zeros corresponding to the DoS,
estimated for square lattice walks of various lengths, and located the
temperature by extrapolating the finite size values of the real zeros to their
asymptotic value, (reasonably close to the known value,
\cite{barkema}).Comment: 18 pages, 7 eps figures; parts of the manuscript are rewritten so as
to improve clarity of presentation; an extra reference adde
Can coarse-graining introduce long-range correlations in a symbolic sequence?
We present an exactly solvable mean-field-like theory of correlated ternary
sequences which are actually systems with two independent parameters. Depending
on the values of these parameters, the variance on the average number of any
given symbol shows a linear or a superlinear dependence on the length of the
sequence. We have shown that the available phase space of the system is made up
a diffusive region surrounded by a superdiffusive region. Motivated by the fact
that the diffusive portion of the phase space is larger than that for the
binary, we have studied the mapping between these two. We have identified the
region of the ternary phase space, particularly the diffusive part, that gets
mapped into the superdiffusive regime of the binary. This exact mapping implies
that long-range correlation found in a lower dimensional representative
sequence may not, in general, correspond to the correlation properties of the
original system.Comment: 10 pages including 1 figur
Lattice Gauge Fields Topology Uncovered by Quaternionic sigma-model Embedding
We investigate SU(2) gauge fields topology using new approach, which exploits
the well known connection between SU(2) gauge theory and quaternionic
projective sigma-models and allows to formulate the topological charge density
entirely in terms of sigma-model fields. The method is studied in details and
for thermalized vacuum configurations is shown to be compatible with
overlap-based definition. We confirm that the topological charge is distributed
in localized four dimensional regions which, however, are not compatible with
instantons. Topological density bulk distribution is investigated at different
lattice spacings and is shown to possess some universal properties.Comment: revtex4, 19 pages (24 ps figures included); replaced to match the
published version, to appear in PRD; minor changes, references adde
Recovery of Ammonium Nitrate and Reusable Acetic Acid from Effluent Generated during HMX Production
Production of HMX on commercial scale is mainly carried out by modified Bachmann process, and acetic acid constitutes major portion of effluenttspent liquor produced during this process. The recovery of glacial acetic acid from this spent liquor is essential to make the process commercially viable besides making it eco-friendly by minimising the quantity of disposable effluent. The recovery of glacial acetic acid from spent liquor is not advisable by simple distillation since it contains, in addition to acetic acid, a small fraction of nitric acid, traces of RDX, HMX, and undesired nitro compounds. The process normally involves neutralising the spent mother liquor with liquor ammonia and then distillating the ueutralised mother liquor under vacuum to recover dilute acetic acid (strength approx. 30 %). The dilute acetic acid, in turn, is concentrated to glacial acetic acid by counter current solvent extraction, followed by distillation. The process is very lengthy and the energy requirement is also veryhigh, rendering the process economically unviable. Hence, a novel method has been developed on bench-scale to obtain glacial acetic acid directly from the mother liquor after the second ageing process
Geometric Phase in Eigenspace Evolution of Invariant and Adiabatic Action Operators
The theory of geometric phase is generalized to a cyclic evolution of the
eigenspace of an invariant operator with -fold degeneracy.
The corresponding geometric phase is interpreted as a holonomy inherited from
the universal connection of a Stiefel U(N)-bundle over a Grassmann manifold.
Most significantly, for an arbitrary initial state, this geometric phase
captures the inherent geometric feature of the state evolution. Moreover, the
geometric phase in the evolution of the eigenspace of an adiabatic action
operator is also addressed, which is elaborated by a pullback U(N)-bundle.
Several intriguing physical examples are illustrated.Comment: Added Refs. and corrected typos; 4 page
Billiard algebra, integrable line congruences, and double reflection nets
The billiard systems within quadrics, playing the role of discrete analogues
of geodesics on ellipsoids, are incorporated into the theory of integrable
quad-graphs. An initial observation is that the Six-pointed star theorem, as
the operational consistency for the billiard algebra, is equivalent to an
integrabilty condition of a line congruence. A new notion of the
double-reflection nets as a subclass of dual Darboux nets associated with
pencils of quadrics is introduced, basic properies and several examples are
presented. Corresponding Yang-Baxter maps, associated with pencils of quadrics
are defined and discussed.Comment: 18 pages, 8 figure
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