1,916 research outputs found
VIBRATION ANALYSIS OF A ROTATING TAPERED COMPOSITE BEAM WITH TIP MASS
In this study, free vibration responses of a rotating tapered composite beam with tip mass are investigated. The energy expressions for the kinetic and potential energies of a rotating composite beam with tip mass have been formulated. The energy expressions are then applied in Lagrange’s equations to develop the equation of motion of a composite beam with tip mass. The stiffness and mass matrices for a standard composite beam element with two end nodes with two degrees of freedom at each node are derived. Various parametric studies are performed to investigate the effect of tip mass and the rotational speed on the variation of natural frequencies of the composite beam. The investigations are also done to study the effect of hub radius on the natural frequencies. It is shown that the addition of tip mass increases the stiffness of the structure and consequently increases the natural frequencies
Separability in Cohomogeneity-2 Kerr-NUT-AdS Metrics
The remarkable and unexpected separability of the Hamilton-Jacobi and
Klein-Gordon equations in the background of a rotating four-dimensional black
hole played an important role in the construction of generalisations of the
Kerr metric, and in the uncovering of hidden symmetries associated with the
existence of Killing tensors. In this paper, we show that the Hamilton-Jacobi
and Klein-Gordon equations are separable in Kerr-AdS backgrounds in all
dimensions, if one specialises the rotation parameters so that the metrics have
cohomogeneity 2. Furthermore, we show that this property of separability
extends to the NUT generalisations of these cohomogeneity-2 black holes that we
obtained in a recent paper. In all these cases, we also construct the
associated irreducible rank-2 Killing tensor whose existence reflects the
hidden symmetry that leads to the separability. We also consider some
cohomogeneity-1 specialisations of the new Kerr-NUT-AdS metrics, showing how
they relate to previous results in the literature.Comment: Latex, 15 pages, minor typos correcte
Particle Motion and Scalar Field Propagation in Myers-Perry Black Hole Spacetimes in All Dimensions
We study separability of the Hamilton-Jacobi and massive Klein-Gordon
equations in the general Myers-Perry black hole background in all dimensions.
Complete separation of both equations is carried out in cases when there are
two sets of equal black hole rotation parameters, which significantly enlarges
the rotational symmetry group. We explicitly construct a nontrivial irreducible
Killing tensor associated with the enlarged symmetry group which permits
separation. We also derive first-order equations of motion for particles in
these backgrounds and examine some of their properties.Comment: 16 pages, LaTeX2
Blade manipulators in turbulent channel flow
We report here the results of a series of careful experiments in turbulent channel flow, using various configurations of blade manipulators suggested as optimal in earlier boundary layer studies. The mass flow in the channel could be held constant to better than 0.1%, and the uncertainties in pressure loss measurements were less than 0.1 mm of water; it was therefore possible to make accurate estimates of the global effects of blade manipulation of a kind that are difficult in boundary layer flows. The flow was fully developed at the station where the blades were mounted, and always relaxed to the same state sufficiently far downstream. It is found that, for a given mass flow, the pressure drop to any station downstream is always higher in the manipulated than in the unmanipulated flow, demonstrating that none of the blade manipulators tried reduces net duct losses. However the net increase in duct losses is less than the drag of the blade even in laminar flow, showing that there is a net reduction in the total skin friction drag experienced by the duct, but this relief is only about 20% of the manipulator drag at most
Separability of Hamilton-Jacobi and Klein-Gordon Equations in General Kerr-NUT-AdS Spacetimes
We demonstrate the separability of the Hamilton-Jacobi and scalar field
equations in general higher dimensional Kerr-NUT-AdS spacetimes. No restriction
on the parameters characterizing these metrics is imposed.Comment: 4 pages, no figure
Wigner distribution transformations in high-order systems
By combining the definition of the Wigner distribution function (WDF) and the
matrix method of optical system modeling, we can evaluate the transformation of
the former in centered systems with great complexity. The effect of stops and
lens diameter are also considered and are shown to be responsible for
non-linear clipping of the resulting WDF in the case of coherent illumination
and non-linear modulation of the WDF when the illumination is incoherent. As an
example, the study of a single lens imaging systems illustrates the
applicability of the method.Comment: 16 pages, 7 figures. To appear in J. of Comp. and Appl. Mat
A Killing tensor for higher dimensional Kerr-AdS black holes with NUT charge
In this paper, we study the recently discovered family of higher dimensional
Kerr-AdS black holes with an extra NUT-like parameter. We show that the inverse
metric is additively separable after multiplication by a simple function. This
allows us to separate the Hamilton-Jacobi equation, showing that geodesic
motion is integrable on this background. The separation of the Hamilton-Jacobi
equation is intimately linked to the existence of an irreducible Killing
tensor, which provides an extra constant of motion. We also demonstrate that
the Klein-Gordon equation for this background is separable.Comment: LaTeX, 14 pages. v2: Typo corrected and equation added. v3: Reference
added, introduction expanded, published versio
Studies on influence of modified atmospheric storage conditions on biochemical parameters in pigeonpea seeds
An experiment was conducted to study the influence of modified atmospheric storage conditions on biochemical parameters of pigeonpea seeds. The experiment was conducted at the Department of Seed Science and Technology, College of Agriculture, Raichur, Karnataka. The seeds are exposed to various gaseous combinationsand stored in 700 gauge polyethylene bag for ten months during July-2012 to April- 2013. The results revealed that, the seeds exposed to gaseous combination of 40% N2+00% O2+ 60% CO2 showed less reduction in dehydrogenase enzyme activity and protein content (0.276 OD (optical density) value, 19.33 % respectively) as compared to the control (0.211 OD value and 18.13 % respectively) after ten months of storage. In addition less seed leachate (2.029 dSm-1) was recorded in gaseous combination of 40% N2+00% O2+ 60% CO2 as compared to control (2.207dSm-1). It indicates the potential use of modified atmospheric storage technology for maintenance of seed viability and vigour during storage in pulses
Complete Integrability of Geodesic Motion in General Kerr-NUT-AdS Spacetimes
We explicitly exhibit n-1 constants of motion for geodesics in the general
D-dimensional Kerr-NUT-AdS rotating black hole spacetime, arising from
contractions of even powers of the 2-form obtained by contracting the geodesic
velocity with the dual of the contraction of the velocity with the
(D-2)-dimensional Killing-Yano tensor. These constants of motion are
functionally independent of each other and of the D-n+1 constants of motion
that arise from the metric and the D-n = [(D+1)/2] Killing vectors, making a
total of D independent constants of motion in all dimensions D. The Poisson
brackets of all pairs of these D constants are zero, so geodesic motion in
these spacetimes is completely integrable.Comment: 4 pages. We have now found that the geodesic motion is not just
integrable, but completely integrabl
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