2,204 research outputs found
Experimental Investigation and Mathematical Modelling to Study thePremixed Laminar Flame Propagation
n the present work, experiments are conducted on a newly designed flame propagation testunit using burners of different geometries (L/D ratio) at different air-fuel ratios to calculate theflame speed. From the experimental data obtained, design plots are drawn to study the flamestability zone under different conditions. Using the above test results and standard mathematicalcurve fitting techniques for a function of two variables, an equation has been derived which canbe utilised by the designers to design an optimum burner for premixed flames which providesstable flame with maximum flame speed for the best burner geometry
Effectiveness of earthquake selection and scaling method in New Zealand
In New Zealand, time history analysis is either the required or preferred method of assessing seismic demands for torsionally sensitive and other important structures, but the criteria adopted for the selection of ground motion records and their scaling to generate the seismic demand remains a contentious and debatable issue. In this paper, the scaling method based on the least squares fit of response spectra between 0.4-1.3 times the structure's first mode period as stipulated in the New Zealand Standard for Structural Design Actions: Earthquake Actions (NZS1170.5) [1] is compared with the scaling methods in which ground motion records are scaled to match the peak ground acceleration (PGA) and spectral acceleration response at the natural period of the structure corresponding to the first mode with 5% of critical damping; i.e. Sa(TI, 5%). Incremental dynamic analysis (IDA) is used to measure the record-torecord randomness of structural response, which is also a measure of the efficiency of the intensity measure (IM) used. Comparison of the dispersions of IDA curves with the three different IMs; namely PGA, Sa(Ti, 5%) and NZS1170.5 based TM, shows that the NZS1170.5 scaling method is the most effective for a large suite of ground motions. Nevertheless, the use of only three randomly chosen ground motions as presently permitted by NZS1170.5 is found to give significantly low confidence in the predicted seismic demand. It is thus demonstrated that more records should be used to provide a robust estimate of likely seismic demand
The effect of density dependent emigration on spread of infectious diseases: a modelling study
In this study, we proposed and analyzed an SIS mathematicalmodel by considering population densitydependent emigration. It is assumed that the diseaseis transmitted by direct contact of infective and susceptiblepopulations. We also assumed that the rate ofcontact is emigration dependent i.e. contact rate is variablewhich depends on the current population of habitatas well as on non-emigrating population density of habitat.The equilibria and their stability are studied by usingthe stability theory of differential equations and simulation.The model analysis shows that the spread of infectiousdisease in habitat decreases if the rate of emigrationincreases but it increases as the population density of nonemigratingpopulation increases. The simulation study ofthe model confirms these analytical results
Rotation and twist regular modes for trapped ghosts
A parameter-independent notion of stationary slow motion is formulated then
applied to the case of stationary rotation of massless trapped ghosts. The
excitations correspond to a rotation mode with angular momentum and
twist modes. It is found that the rotation mode, which has no parity, causes
excess in the angular velocity of dragged distant coordinate frames in one
sheet of the wormhole while in the other sheet the angular velocity of the
ghosts is that of rotating stars: . As to the twist modes, which all
have parity, they cause excess in the angular velocity of one of the throat's
poles with respect to the other.Comment: 11 pages, 3 figures; General Relativity and Gravitation - 201
Effect of Lates calcarifer seed stocking on the survival and production of Indian major carps reared in a freshwater coastal pond in Konkan region
The experiment indicated feasibility of culturing Indian major carps seed with Lates calcarifer, if the size of Indian major carps is larger. In the present investigation the average growths of Catla catla, Labeo rohita and Cirrhinus mrigala are recorded as 1193, 1120 and 821 g, respectively, during the year 1997-98, 1998-99 and 1999-2000 in 7.5 months. Complete harvesting of L. calcarifer is essential before stocking of new seed. The average growth of L. calcarifer was recorded as about 670 g during the above period. About 5000 numbers of Indian major carps fry per hectare can be stocked under the present culture syste
Consistent Histories in Quantum Cosmology
We illustrate the crucial role played by decoherence (consistency of quantum
histories) in extracting consistent quantum probabilities for alternative
histories in quantum cosmology. Specifically, within a Wheeler-DeWitt
quantization of a flat Friedmann-Robertson-Walker cosmological model sourced
with a free massless scalar field, we calculate the probability that the
univese is singular in the sense that it assumes zero volume. Classical
solutions of this model are a disjoint set of expanding and contracting
singular branches. A naive assessment of the behavior of quantum states which
are superpositions of expanding and contracting universes may suggest that a
"quantum bounce" is possible i.e. that the wave function of the universe may
remain peaked on a non-singular classical solution throughout its history.
However, a more careful consistent histories analysis shows that for arbitrary
states in the physical Hilbert space the probability of this Wheeler-DeWitt
quantum universe encountering the big bang/crunch singularity is equal to
unity. A quantum Wheeler-DeWitt universe is inevitably singular, and a "quantum
bounce" is thus not possible in these models.Comment: To appear in Foundations of Physics special issue on quantum
foundation
Cosmological constraints on the generalized holographic dark energy
We use the Markov ChainMonte Carlo method to investigate global constraints
on the generalized holographic (GH) dark energy with flat and non-flat universe
from the current observed data: the Union2 dataset of type supernovae Ia
(SNIa), high-redshift Gamma-Ray Bursts (GRBs), the observational Hubble data
(OHD), the cluster X-ray gas mass fraction, the baryon acoustic oscillation
(BAO), and the cosmic microwave background (CMB) data. The most stringent
constraints on the GH model parameter are obtained. In addition, it is found
that the equation of state for this generalized holographic dark energy can
cross over the phantom boundary wde =-1.Comment: 14 pages, 5 figures. arXiv admin note: significant text overlap with
arXiv:1105.186
A Hybrid Approach to Cognition in Radars
In many engineering domains, cognition is emerging to play vital role. Cognition will play crucial role in radar engineering as well for the development of next generation radars. In this paper, a cognitive architecture for radars is introduced, based on hybrid cognitive architectures. The paper proposes deep learning applications for integrated target classification based on high-resolution radar range profile measurements and target revisit time calculation as case studies. The proposed architecture is based on the artificial cognitive systems concepts and provides a basis for addressing cognition in radars, which is inadequately explored for radar systems. Initial experimental studies on the applicability of deep learning techniques under this approach provided promising results
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