140 research outputs found
Dynamics of quasi-one-dimensional bright and vortex solitons of a dipolar Bose-Einstein condensate with repulsive atomic interaction
By numerical and variational analysis of the three-dimensional
Gross-Pitaevskii equation we study the formation and dynamics of bright and
vortex-bright solitons in a cigar-shaped dipolar Bose-Einstein condensate for
large repulsive atomic interactions. Phase diagram showing the region of
stability of the solitons is obtained. We also study the dynamics of breathing
oscillation of the solitons as well as the collision dynamics of two solitons
at large velocities. Two solitons placed side-by-side at rest coalesce to form
a stable bound soliton molecule due to dipolar attraction.Comment: To obtain the included video clips S1, S2, S3 and S4, please download
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Matter wave switching in Bose-Einstein condensates via intensity redistribution soliton interactions
Using time dependent nonlinear (s-wave scattering length) coupling between
the components of a weakly interacting two component Bose-Einstein condensate
(BEC), we show the possibility of matter wave switching (fraction of atoms
transfer) between the components via shape changing/intensity redistribution
(matter redistribution) soliton interactions. We investigate the exact
bright-bright N-soliton solution of an effective one-dimensional (1D) two
component BEC by suitably tailoring the trap potential, atomic scattering
length and atom gain or loss. In particular, we show that the effective 1D
coupled Gross-Pitaevskii (GP) equations with time dependent parameters can be
transformed into the well known completely integrable Manakov model described
by coupled nonlinear Schr\"odinger (CNLS) equations by effecting a change of
variables of the coordinates and the wave functions under certain conditions
related to the time dependent parameters. We obtain the one-soliton solution
and demonstrate the shape changing/matter redistribution interactions of two
and three soliton solutions for the time independent expulsive harmonic trap
potential, periodically modulated harmonic trap potential and kink-like
modulated harmonic trap potential. The standard elastic collision of solitons
occur only for a specific choice of soliton parameters.Comment: 11 pages, 14 figures, 1 tabl
Comment on ``Intermittent Synchronization in a Pair of Coupled Chaotic Pendula"
The main aim of this comment is to emphasize that the conditional Lyapunov
exponents play an important role in distinguishing between intermittent and
persistent synchronization, when the analytic criteria for asymptotic stability
are not uniformly obeyed.Comment: 2 pages, RevTeX 4, 1 EPS figur
Physicochemical evaluation of common purslane (Portulaca oleracea L.) accessions through correlation and regression
It is important to look at the physicochemical qualities of Portulaca, a weed species used as a vegetable and a herb for medical and therapeutic purposes. India has a wide range of variations in this species' morphology and nutraceutical value. This study aimed to evaluate the physicochemical properties of various purslane accessions from different regions of Tamil Nadu. A total of 15 purslane accessions (PA 1, PA 2, PA 3, PA 4, PA 5, PA 6, PA 7, PA 8, PA 9, PA 10, PA 11, PA 12, PA 13, PA 14 and PA 15) were collected and evaluated. Physical traits like colour of the leaves and stems were quantified as hue angle and chroma value, which showed a degree of variation. Estimates suggested that phytochemical properties related the hue and chroma of leaf and stem to the pigments in plants. Among the accessions, PA 3 has recorded the highest phytochemical properties viz., leaf total chlorophyll content 1.43±0.16 mg g-1, leaf total carotenoid content 0.24±0.03 mg g-1, stem total chlorophyll content 0.49±0.05 mg g-1, stem total carotenoid content 0.12±0.01 mg g-1 and total anthocyanin content 19.25±1.54 µg g-1. The multiple regression model suggested that the values can predict the estimated values. The evaluation of physicochemical properties along with the regression model helps in the breeding programme to select the traits; phytochemical analysis proved the ample supply of chlorophylls, carotenoids and anthocyanins, so these wild species could be a cheap source to alleviate several diseases.    Â
PRABHA - A New Heuristic Approach For Machine Cell Formation Under Dynamic Production Environments
Over the past three decades, Cellular Manufacturing Systems (CMS) have attracted a lot of attention from manufacturers because of its positive impacts on analysis of batch-type production and also a wide range of potential application areas. Machine cell formation and part family creation are two important tasks of cellular manufacturing systems. Most of the current CMS design methods have been developed for a static production environment. This paper addresses the problem of machine cell formation and part family formation for a dynamic production requirement with the objective of minimizing the material handling cost, penalty for cell load variation and the machine relocation cost. The parameters considered include demand of parts in different period, routing sequences, processing time and machine capacities. In this work a new heuristic approach named PRABHA is proposed for machine cell formation and the part family formation. The computational results of the proposed heuristics approach were obtained and compared with the Genetic Algorithm approach and it was found that the proposed heuristics PRABHA outperforms the Genetic Algorithm
In vitro evaluation of antimicrobial properties of a new Mannich base N-[(Diphenylamino)methyl]acrylamide and its Oxovanadium(IV), Cerium(IV), Thorium(IV) and Dioxouranium(VI) metal chelates against human pathogenic microorganisms
N-[(Diphenylamino)methyl]acrylamide(DPAMAcry) was synthesized using Mannich reaction and its complexes of oxovanadium(IV), cerium(IV), thorium(IV) and dioxouranium(VI) were prepared and characterized by elemental analysis, UV, IR and EPR spectral studies. All the newly synthesized compounds have been screened for their antibacterial and antifungal activities. All of them show promising antibacterial and antifungal activity
Scaling and synchronization in a ring of diffusively coupled nonlinear oscillators
Chaos synchronization in a ring of diffusively coupled nonlinear oscillators
driven by an external identical oscillator is studied. Based on numerical
simulations we show that by introducing additional couplings at -th
oscillators in the ring, where is an integer and is the maximum
number of synchronized oscillators in the ring with a single coupling, the
maximum number of oscillators that can be synchronized can be increased
considerably beyond the limit restricted by size instability. We also
demonstrate that there exists an exponential relation between the number of
oscillators that can support stable synchronization in the ring with the
external drive and the critical coupling strength with a scaling
exponent . The critical coupling strength is calculated by numerically
estimating the synchronization error and is also confirmed from the conditional
Lyapunov exponents (CLEs) of the coupled systems. We find that the same scaling
relation exists for couplings between the drive and the ring. Further, we
have examined the robustness of the synchronous states against Gaussian white
noise and found that the synchronization error exhibits a power-law decay as a
function of the noise intensity indicating the existence of both noise-enhanced
and noise-induced synchronizations depending on the value of the coupling
strength . In addition, we have found that shows an
exponential decay as a function of the number of additional couplings. These
results are demonstrated using the paradigmatic models of R\"ossler and Lorenz
oscillators.Comment: Accepted for Publication in Physical Review
Self-trapping of a binary Bose-Einstein condensate induced by interspecies interaction
The problem of self-trapping of a Bose-Einstein condensate (BEC) and a binary
BEC in an optical lattice (OL) and double well (DW) is studied using the
mean-field Gross-Pitaevskii equation. For both DW and OL, permanent
self-trapping occurs in a window of the repulsive nonlinearity of the GP
equation: . In case of OL, the critical nonlinearities
and correspond to a window of chemical potentials
defining the band gap(s) of the periodic OL. The
permanent self-trapped BEC in an OL usually represents a breathing oscillation
of a stable stationary gap soliton. The permanent self-trapped BEC in a DW, on
the other hand, is a dynamically stabilized state without any stationary
counterpart. For a binary BEC with intraspecies nonlinearities outside this
window of nonlinearity, a permanent self trapping can be induced by tuning the
interspecies interaction such that the effective nonlinearities of the
components fall in the above window
Studies on Droplet Size Distribution of Oil-in-Water Emulsion in SMX Static Mixer
Oil droplet size distribution of an emulsion produced by Sulzer Chemtech's static SMX static mixer under flow condition was experimentally studied and reported. The dispersed phase of vegetable oil-in-water (O/W) emulsion produced through static mixer by varying the concentration from 1 to 4 vol % oil in water, flowrate of dispersed and continuous phase and operating time. The effect of run time on oil drop sizes is characterized using the spectra obtained from the particle size analyser. The static mixer with 9 perpendicular elements made of teflon is stacked against each other had a void fraction of 0.93. The sauter mean diameter of oil droplet decreases from 8 µm to 4 µm with an increase in Reynolds number. The emulsion droplets of mean sauter diameter in the range 4.1 µm to 4.7 µm were produced by increasing the concentration of the dispersed phase from 1:100 to 1:25, within a span value of between 30 to 240 sec, at atmospheric pressure and room temperature. Performance equation for sauter mean oil droplet diameter is developed based on the experimental data has ±0.2 rms deviation
Dynamics of fluctuations in an optical analog of the Laval nozzle
Using the analogy between the description of coherent light propagation in a
medium with Kerr nonlinearity by means of nonlinear Schr\"odinger equation and
that of a dissipationless liquid we propose an optical analogue of the Laval
nozzle. The optical Laval nozzle will allow one to form a transonic flow in
which one can observe and study a very unusual dynamics of classical and
quantum fluctuations including analogue of the Hawking radiation of real black
holes. Theoretical analysis of this dynamics is supported by numerical
calculations and estimates for a possible experimental setup are presented.Comment: 7 pages, 4 figure
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