Communication Standards Adoption in Developing Economies: Issues and Options for India

Given the importance of communications in todays world, its spread in developing economies is critical for their development. Emergence of standards reduces market and technological uncertainty and lays the foundation for market creation and enhances the diffusion of communication technologies partly through the advantages associated with network and scale economies. Standardisation has also become important with the rise in cross-fertilisation between information technology (IT) and other technologies, especially in communications. Under these circumstances, strategic implications of IT standardisation are huge because standards can determine the growth potential of individual firms, affect the competitive advantage of nations and even development of technologies and their diffusion. Policies for standards adoption have been used world-wide to facilitate the diffusion of communications technologies, acquire a larger market share of the global telecom market, build technological capabilities. The paper reviews various approaches to communications standard adoption as well as the experiences of other countries. These approaches and experiences and the associated market and regulatory failures are evaluated in the context of the current Indian situation. This evaluation suggests that a standards neutral policy is desirable for India.

Flow diagnosis in a domestic radiator

In UK, domestic heating contributes to about 40% of annual energy consumption. Effective and efficient heating systems are essential to drive the cost of heating down. Although there are several types of heating systems, radiators are the most popular heat emitters. Head loss in a radiator depends on various design parameters based on fluid flow path conditions and design of the radiator. In the present study, a computational fluid dynamics (CFD) code has been used to analyse flow distribution within a domestic radiator. For this study a radiator with dimensions of 300mm by 600mm with 18 columns has been considered. The study has been carried out on a radiator with BBOE and BTOE configuration at various flow rates. In this paper results are presented from a series of analysis in which flow structure within the radiator has been diagnosed

Differential influence of DNA supercoiling on in vivo strength of promoters varying in structure and organisation in E. coli

AbstractDNA supercoiling is known to influence promoter activity in vitro and in vivo in a promoter-dependent manner in prokaryotes. In order to investigate how topology may influence promoter function, we have studied two kinds of promoter variants, (i) where only the spacer region is altered, and (ii) where the same promoter is tandemly repeated in either the same or opposite orientation. These promoters respond very differently to alterations in DNA supercoiling, suggesting that the overall structure of the promoter and its context contribute to the differential response to alterations in supercoiling in vivo

Finite beam curvature related patterns in a saturable medium

We study numerically the effects of finite curvature and ellipticity of the Gaussian beam on propagation through a saturating nonlinear medium. We demonstrate generation of different types of pattern arising from the input phase structure as well as the phase structure imparted by the nonlinear medium

Approximate inversion of the wave-equation Hessian via randomized matrix probing

We present a method for approximately inverting the Hessian of full waveform inversion as a dip-dependent and scale-dependent amplitude correction. The terms in the expansion of this correction are determined by least-squares fitting from a handful of applications of the Hessian to random models — a procedure called matrix probing. We show numerical indications that randomness is important for generating a robust preconditioner, i.e., one that works regardless of the model to be corrected. To be successful, matrix probing requires an accurate determination of the nullspace of the Hessian, which we propose to implement as a local dip-dependent mask in curvelet space. Numerical experiments show that the novel preconditioner fits 70% of the inverse Hessian (in Frobenius norm) for the 1-parameter acoustic 2D Marmousi model.National Science Foundation (U.S.); Alfred P. Sloan Foundatio

Magnonic Crystal with Two-Dimensional Periodicity as a Waveguide for Spin Waves

We describe a simple method of including dissipation in the spin wave band structure of a periodic ferromagnetic composite, by solving the Landau-Lifshitz equation for the magnetization with the Gilbert damping term. We use this approach to calculate the band structure of square and triangular arrays of Ni nanocylinders embedded in an Fe host. The results show that there are certain bands and special directions in the Brillouin zone where the spin wave lifetime is increased by more than an order of magnitude above its average value. Thus, it may be possible to generate spin waves in such composites decay especially slowly, and propagate especially large distances, for certain frequencies and directions in ${\bf k}$-space.Comment: 13 pages, 4 figures, submitted to Phys Rev

Euler/Navier-Stokes Solvers Applied to Ducted Fan Configurations

Due to noise considerations, ultra high bypass ducted fans have become a more viable design. These ducted fans typically consist of a rotor stage containing a wide chord fan and a stator stage. One of the concerns for this design is the classical flutter that keeps occurring in various unducted fan blade designs. These flutter are catastrophic and are to be avoided in the flight envelope of the engine. Some numerical investigations by Williams, Cho and Dalton, have suggested that a duct around a propeller makes it more unstable. This needs to be further investigated. In order to design an engine to safely perform a set of desired tasks, accurate information of the stresses on the blade during the entire cycle of blade motion is required. This requirement in turn demands that accurate knowledge of steady and unsteady blade loading be available. Aerodynamic solvers based on unsteady three-dimensional analysis will provide accurate and fast solutions and are best suited for aeroelastic analysis. The Euler solvers capture significant physics of the flowfield and are reasonably fast. An aerodynamic solver Ref. based on Euler equations had been developed under a separate grant from NASA Lewis in the past. Under the current grant, this solver has been modified to calculate the aeroelastic characteristics of unducted and ducted rotors. Even though, the aeroelastic solver based on three-dimensional Euler equations is computationally efficient, it is still very expensive to investigate the effects of multiple stages on the aeroelastic characteristics. In order to investigate the effects of multiple stages, a two-dimensional multi stage aeroelastic solver was also developed under this task, in collaboration with Dr. T. S. R. Reddy of the University of Toledo. Both of these solvers were applied to several test cases and validated against experimental data, where available