Wide parameter search for isolated pulsars using the Hough transform

We use the Hough transform to analyze data from the second science run of the LIGO interferometers, to look for gravitational waves from isolated pulsars. We search over the whole sky and over a large range of frequencies and spin-down parameters. Our search method is based on the Hough transform, which is a semi-coherent, computationally efficient, and robust pattern recognition technique. We also present a validation of the search pipeline using hardware signal injections.Comment: Presented at GWDAW-9 in Annecy, France (Dec. 2004). 11 pages, 5 Figures. To appear in Classical and Quantum Gravit

ഏകവർഗ്ഗ മത്സ്യകൃഷി (Monoculture of finfish) Malayalam

ഏകവർഗ്ഗ മത്സ്യകൃഷ

Inflatonless Inflation

We consider a 4+N dimensional Einstein gravity coupled to a non-linear sigma model. This theory admits a solution in which the N extra dimensions contract exponentially while the ordinary space expand exponentially. Physically, the non-linear sigma fields induce the dynamical compactification of the extra dimensions, which in turn drives inflation. No inflatons are required.Comment: 12 pages, version to appear in IJMP

Some Critical Issues in the Processing of Magnesium Alloys & Composites

Handling of molten Mg alloys and composite slurries is risky due to the danger of explosion and oxidation in contact with O, of the atmosphere and water. Hence special attention is to be taken for safety and quality in all steps of processingmelting.moulding. casting, heat treatment and mechanical working. The limitations and specialities are in respect of alloying (viz.with Zr.Mn-Ca_Be), removal of nonmetallic and metallic impurities (viz.Fc.Ni etc), grain refinement. degassing. choice of flues and the mariner of its addition. die design for extrusion. selection of temperature and time in melting. pouring and heat treatment- selection of stirrer rpm- its geometry and location in the bath for composite making by stir casting including nccocasting methods etc. These issues are revieNwd in this paper

Building block method: a bottom-up modular synthesis methodology for distributed compliant mechanisms

Synthesizing topologies of compliant mechanisms are based on rigid-link kinematic designs or completely automated optimization techniques. These designs yield mechanisms that match the kinematic specifications as a whole, but seldom yield user insight on how each constituent member contributes towards the overall mechanism performance. This paper reviews recent developments in building block based design of compliant mechanisms. A key aspect of such a methodology is formulating a representation of compliance at a (i) single unique point of interest in terms of geometric quantities such as ellipses and vectors, and (ii) relative compliance between distinct input(s) and output(s) in terms of load flow. This geometric representation provides a direct mapping between the mechanism geometry and their behavior, and is used to characterize simple deformable members that form a library of building blocks. The design space spanned by the building block library guides the decomposition of a given problem specification into tractable sub-problems that can be each solved from an entry in the library. The effectiveness of this geometric representation aids user insight in design, and enables discovery of trends and guidelines to obtain practical conceptual designs

Using gravitational waves to distinguish between neutron stars and black holes in compact binary mergers

In August 2017, the first detection of a binary neutron star merger,GW170817, made it possible to study neutron stars in compact binary systemsusing gravitational waves. Despite being the loudest (in terms ofsignal-to-noise ratio) gravitational wave detected to date, it was not possibleto unequivocally determine that GW170817 was caused by the merger of twoneutron stars instead of two black holes from the gravitational-wave dataalone. That distinction was largely due to the accompanying electromagneticcounterpart. This raises the question: under what circumstances cangravitational-wave data alone, in the absence of an electromagnetic signal, beused to distinguish between different types of mergers? Here, we study whethera neutron-star--black-hole binary merger can be distinguished from a binaryblack hole merger using gravitational-wave data alone. We build on earlierresults using chiral effective field theory to explore whether the data fromLIGO and Virgo, LIGO A+, LIGO Voyager, or Cosmic Explorer could lead to such adistinction. The results suggest that the present LIGO-Virgo detector networkwill most likely be unable to distinguish between these systems even with theplanned near-term upgrades. However, given an event with favorable parameters,third-generation instruments such as Cosmic Explorer will be capable of makingthis distinction. This result further strengthens the science case forthird-generation detectors.<br

On the diffraction of light by spherical obstacles

The diffraction of light inside the shadow, thrown by a small source of light, of a sphere and a circular disc of the same diameter, was studied, with special reference to the relative intensities of the central bright spots. With the source at about 2 metres from the obstacles, with a quarter-inch polished steel ball, the bright spot could be detected visually up to 3 cm. behind the obstacle, while with a steel disc of the same diameter, with the edges perfectly sharp, smooth and circular, the spot could be traced up to 2 cm. The relative intensities of the two spots were studied at different distances behind the obstacles, qualitatively by photography and quantitatively by visual photometry. At small distances behind the obstacles, the spot inside the shadow of the sphere is much feebler than the disc-spot, however approximating to the latter as we reach farther back from the obstacles, but even at 100 cm. remaining appreciably feebler. A general explanation is suggested