3,202 research outputs found
Global behavior of cosmological dynamics with interacting Veneziano ghost
In this paper, we shall study the dynamical behavior of the universe
accelerated by the so called Veneziano ghost dark energy component locally and
globally by using the linearization and nullcline method developed in this
paper. The energy density is generalized to be proportional to the Hawking
temperature defined on the trapping horizon instead of Hubble horizon of the
Friedmann-Robertson-Walker (FRW) universe. We also give a prediction of the
fate of the universe and present the bifurcation phenomenon of the dynamical
system of the universe. It seems that the universe could be dominated by dark
energy at present in some region of the parameter space.Comment: 8 pages, 7 figures, accepted for publication in JHE
Comets, historical records and vedic literature
A verse in book I of Rigveda mentions a cosmic tree with rope-like aerial
roots held up in the sky. Such an imagery might have ensued from the appearance
of a comet having `tree stem' like tail, with branched out portions resembling
aerial roots. Interestingly enough, a comet referred to as `heavenly tree' was
seen in 162 BC, as reported by old Chinese records. Because of weak surface
gravity, cometary appendages may possibly assume strange shapes depending on
factors like rotation, structure and composition of the comet as well as solar
wind pattern. Varahamihira and Ballala Sena listed several comets having
strange forms as reported originally by ancient seers such as Parashara,
Vriddha Garga, Narada and Garga.
Mahabharata speaks of a mortal king Nahusha who ruled the heavens when Indra,
king of gods, went into hiding. Nahusha became luminous and egoistic after
absorbing radiance from gods and seers. When he kicked Agastya (southern star
Canopus), the latter cursed him to become a serpent and fall from the sky. We
posit arguments to surmise that this Mahabharata lore is a mythical recounting
of a cometary event wherein a comet crossed Ursa Major, moved southwards with
an elongated tail in the direction of Canopus and eventually went out of sight.
In order to check whether such a conjecture is feasible, a preliminary list of
comets (that could have or did come close to Canopus) drawn from various
historical records is presented and discussed.Comment: This work was presented in the International Conference on Oriental
Astronomy held at IISER, Pune (India) during November, 201
Cluster synchronization of nonlinearly coupled complex networks via pinning control
Author name used in this publication: Francis AustinVersion of RecordPublishe
Grouted jetted precast concrete sheet piles: Method, experiments, and applications
This paper introduces an innovative technology - grouted jetted precast concrete piling - that increases the efficiency of piling operations in coastal regions. The technology includes the following steps: (i) casting concrete piles factory-designed especially for jetting and grouting; (ii) jetting to drive the concrete piles with a crane on a floating ship or platform into soil; and (iii) grouting to enhance the sheet pile connections and to increase the pile bearing capacity. This technology was applied to a number of piling construction projects at the mouth of the Yellow River Delta in China, and this experience demonstrated that it is a robust, fast track, cost-effective, and environmentally friendly piling method. © 2006 NRC Canada.published_or_final_versio
Mean-square exponential synchronization of Markovian switching stochastic complex networks with time-varying delays by pinning control
Author name used in this publication: Francis Austin2011-2012 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe
Reversible lithium storage in sp² hydrocarbon frameworks
Polymer materials offer controllable structure-dependent performances in separation, catalysis and drug release. Their molecular structures can be precisely tailored to accept Li+ for energy storage applications. Here the design of sp2 carbon-based polyphenylene (PPH) with high lithium-ion uptakes and long-term stability is reported. Linear-PPH (L-PPH) exceeds the performance of crosslink-PPH (C-PPH), due to the fact that it has an ordered lamellar structure, promoting the Li+ intercalation/deintercalation channel. The L-PPH cell shows a clear charge and discharge plateau at 0.35 and 0.15 V vs. Li+/Li, respectively, which is absent in the C-PPH cell. The Li+ storage capacity of L-PPH is five times that of the C-PPH. The reversible storage capacity is further improved to 261 mAh g−1 by functionalizing the L-PPH with the –SO3H groups. In addition, the Li-intercalated structures of C-PPH and L-PPH are investigated via near-edge X-ray absorption fine structure (NEXAFS), suggesting the high reversible Li+ - C=C bond interaction at L-PPH. This strategy, based on new insight into sp2 functional groups, is the first step toward a molecular understanding of the structure storage-capacity relationship in sp2 carbon-based polymer
Coefficient, Distortion and Growth Inequalities for Certain Close-to-Convex Functions
In the present investigation, certain subclasses of close-to-convex functions
are investigated. In particular, we obtain an estimate for the Fekete-Szeg\"o
functional for functions belonging to the class, distortion, growth estimates
and covering theorems
In situ visualization by X-Ray computed tomography on sulfur stabilization and lithium polysulfides immobilization in S@HCS/MnOₓ cathode
The lithium-sulfur (Li-S) batteries have high theoretical energy density, exceeding that of the lithium-ion batteries. However, their practical applications are hindered by the capacity decay due to lithium polysulfide shuttle effect and sulfur volume expansion. Here, we design a S@hollow carbon with porous shell/MnOx (S@HCS/MnOx) cathode to accommodate and immobilize sulfur and polysulfides, and develop a non-destructive technique X-ray computed tomography (X-ray CT) to in situ visualize the volume expansion of Li-S cathode. The designed cathode achieves a specific capacity of ∼1100 mAh g-1 at 0.2 C with a fade rate of 0.18% per cycle over 300 cycles. The X-ray CT shows that only 16% volume expansion and 70% volume fraction of solid sulfur remaining in the S@HCS/MnOx cathode, superior to the commercial cathode with 40% volume expansion and 5% volume remaining of solid sulfur particles. This is the first reported visualization evidence for the effectiveness of hollow carbon structure in accommodating cathode volume expansion and immobilizing sulfur shuttling. X-ray CT can serve as a powerful in situ tool to trace the active materials and then feedback to the structure design, which helps develop efficient and reliable energy storage systems
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