Indian Institute of Technology Bombay

About: Indian Institute of Technology Bombay is a education organization based out in Mumbai, India. It is known for research contribution in the topics: Population & Thin film. The organization has 16756 authors who have published 33588 publications receiving 570559 citations.

Determining optical flow for irregular domains by minimizing quadratic functionals of a certain class

Abstract: Snyder (1989) has recently classified all smoothness terms which involve first-order derivatives of the flowfield u(x, t) and of the image grey-value function g(x, t). The physically plausible smoothness terms belonging to this class are known from the work of Horn and Schunck (1981) and Nagel (1987). In this paper we discuss the possibilities of approximating the solutions to the minimization problems of Horn & Schunk (1981) and Nagel (1987). In particular, it is shown that these solutions exist, are unique, and depend continuously on the input data. These properties make it possible, while taking into consideration arbitrary models of the grey-value function, to approximate efficiently the (weak) solutions of the associated boundary-value problems in irregularly shaped domains (with a “sufficiently smooth” boundary) using finite elements. Experiments with image sequences from synthetic as well as outdoor scenes show how the orientation dependency of the smoothness term in Nagel's approach influences the results.

Rational design of an electrochromic polymer with high contrast in the visible region: dibenzyl substituted poly(3,4-propylenedioxythiophene)

Abstract: A dibenzyl substituted poly(3,4-propylenedioxythiophene) was designed and synthesized, and exhibited a contrast of 89% at 632 nm with switching speeds of 400 ms and coloration efficiency of 575 cm2 C−1.

Fatigue and fracture toughness characteristics of laser rapid manufactured Inconel 625 structures

Abstract: Fatigue crack growth and fracture toughness characteristics of laser rapid manufactured (LRMed) Inconel 625 compact tension specimens of thickness 12 and 25 mm were investigated. Fatigue crack propagation in all the specimens investigated in the stress intensity range (Δ K ) of 14–38 MPa√m, exhibited stage II crack growth in Paris’ regime with nearly same slopes of crack growth per cycle versus Δ K plot. Fatigue crack growth rates in the LRMed specimens of present study were found to be lower than the reported values for wrought Inconel 625 in the Δ K range of 14–24 MPa√m and above this range they tended to coincide. X-ray diffraction patterns of the fractured surfaces revealed that the crack propagated along the growth direction of the specimens which was predominantly along the (1 1 1) plane. The fracture toughness values ( J 0.2 ) for LRMed Inconel 625 specimens were found to be in the range of about 200–255 kJ/m 2 . The LRMed specimens exhibited stable crack growth during the J -integral test.

K*(892)(0) and phi(1020)meson production at high transverse momentum in pp and Pb-Pb collisions at root sNN=2.76 TeV

Abstract: The production of K∗(892)0 and φ(1020) mesons in proton-proton (pp) and lead-lead (Pb-Pb) collisions at sNN=2.76TeV has been analyzed using a high luminosity data sample accumulated in 2011 with the ALICE detector at the Large Hadron Collider (LHC). Transverse momentum (pT) spectra have been measured for K∗(892)0 and φ(1020) mesons via their hadronic decay channels for pT up to 20GeV/c. The measurements in pp collisions have been compared to model calculations and used to determine the nuclear modification factor and particle ratios. The K∗(892)0/K ratio exhibits significant reduction from pp to central Pb-Pb collisions, consistent with the suppression of the K∗(892)0 yield at low pT due to rescattering of its decay products in the hadronic phase. In central Pb-Pb collisions the pT dependent φ(1020)/π and K∗(892)0/π ratios show an enhancement over pp collisions for pT≈3GeV/c, consistent with previous observations of strong radial flow. At high pT, particle ratios in Pb-Pb collisions are similar to those measured in pp collisions. In central Pb-Pb collisions, the production of K∗(892)0 and φ(1020) mesons is suppressed for pT>8GeV/c. This suppression is similar to that of charged pions, kaons, and protons, indicating that the suppression does not depend on particle mass or flavor in the light quark sector.

Seismic response of isolated bridges

Abstract: The response of bridges seismically isolated by lead-rubber bearings (L-RB) to bidirectional earthquake excitation (i.e., 2 horizontal components) is presented. The force-deformation behavior of L-RB is considered as bilinear, and the interaction between the restoring forces in 2 orthogonal horizontal directions is duly considered in the response analysis. The specific purpose of the study is to assess the effects of seismic isolation on the peak response of the bridges, and to investigate the effects of the bidirectional interaction of restoring forces of isolation bearings. The seismic response of the lumped mass model of continuous span isolated bridges is obtained by solving the governing equations of motion in the incremental form using an iterative step-by-step method. To study the effectiveness of L-RB, the seismic response of isolated bridges is compared with the response of corresponding nonisolated bridges (i.e., bridges without isolation devices). A comparison of the response of the isolated bridges obtained by considering and ignoring the bidirectional interaction of bearing forces is made under important parametric variation. The important parameters included are the flexibility of bridge piers and the stiffness and yield strength of the L-RB. Results show the bidirectional interaction of the restoring forces of the L-RB has considerable effects on the seismic response of isolated bridges. If these interaction effects are ignored, then the peak bearing displacements are underestimated which can be crucial from a design point of view.