Acoustic gravity waves: A computational approach

This paper discusses numerical solutions of a hyperbolic initial boundary value problem that arises from acoustic wave propagation in the atmosphere. Field equations are derived from the atmospheric fluid flow governed by the Euler equations. The resulting original problem is nonlinear. A first order linearized version of the problem is used for computational purposes. The main difficulty in the problem as with any open boundary problem is in obtaining stable boundary conditions. Approximate boundary conditions are derived and shown to be stable. Numerical results are presented to verify the effectiveness of these boundary conditions

Four-photon interference: a realizable experiment to demonstrate violation of EPR postulates for perfect correlations

Bell's theorem reveals contradictions between the predictions of quantum mechanics and the EPR postulates for a pair of particles only in situations involving imperfect statistical correlations. However, with three or more particles, contradictions emerge even for perfect correlations. We describe an experiment which can be realized in the laboratory, using four-photon entangled states generated by parametric down-conversion, to demonstrate this contradiction at the level of perfect correlations.Comment: publishe

NSSDC Conference on Mass Storage Systems and Technologies for Space and Earth Science Applications, volume 1

Papers and viewgraphs from the conference are presented. This conference served as a broad forum for the discussion of a number of important issues in the field of mass storage systems. Topics include magnetic disk and tape technologies, optical disks and tape, software storage and file management systems, and experiences with the use of a large, distributed storage system. The technical presentations describe, among other things, integrated mass storage systems that are expected to be available commercially. Also included is a series of presentations from Federal Government organizations and research institutions covering their mass storage requirements for the 1990's

NSSDC Conference on Mass Storage Systems and Technologies for Space and Earth Science Applications, volume 2

This report contains copies of nearly all of the technical papers and viewgraphs presented at the NSSDC Conference on Mass Storage Systems and Technologies for Space and Earth Science Application. This conference served as a broad forum for the discussion of a number of important issues in the field of mass storage systems. Topics include the following: magnetic disk and tape technologies; optical disk and tape; software storage and file management systems; and experiences with the use of a large, distributed storage system. The technical presentations describe, among other things, integrated mass storage systems that are expected to be available commercially. Also included is a series of presentations from Federal Government organizations and research institutions covering their mass storage requirements for the 1990's

Experimental Determination of Machining Responses in Machining Austempered Ductile Iron (ADI)

AbstractThis work investigates the machining characteristics of Austempered Ductile Iron (ADI) using Electrical Discharge Machining (EDM) process with copper as an electrode. Experiments have been carried out to analyze the effect of each parameter on the machining characteristics, and to predict the optimal choice for each EDM parameters such as peak current, pulse on time, pulse off time and tool geometry. Three different specimens were austenised at 900° C for 90min and then austempered in a salt bath at 360° C, 380° C, and 400° C for 120min. Experiments have been designed as per Taguchi's L18 orthogonal array. Analysis of variance (ANOVA) is used to find the level of significance of machining parameters. Machining responses such as the metal removal rate (MRR), Tool wear rate (TWR), surface roughness (SR) and taper angle (DVEE) for entrance – exit of the tool was studied while machining the Austempered Ductile Iron (ADI) with copper as an electrode. Discharge current, Pulse on time and Austempering temperature are found most influential parameters on each performance measure. Tool geometry is found the least influential parameters

Analysis of Linear Equalizers for Cooperative Multi-User MIMO Based Reporting System

In this paper, we consider a multi user multiple input multiple output (MU-MIMO) based cooperative reporting system for cognitive radio network. In the reporting network, the secondary users forwards the primary user data to the common fusion center (FC). The FC is equipped with linear equalizers and an energy detector to make the decision about the spectrum. The primary user data is considered to be a digital video broadcasting - terrestrial (DVB-T) signal. The sensing channel and the reporting channel is assumed to be an additive white Gaussian noise and an independent identically distributed Raleigh fading respectively. We analyzed the detection probability of MU-MIMO system with linear equalizers and arrived at closed form expression for average detection probability. Also the system performance is investigated under various MIMO scenarios through Monte Carlo simulations

Analysis of Linear Equalizers for Cooperative Multi-User MIMO Based Reporting System

In this paper, we consider a multi user multiple input multiple output (MU-MIMO) based cooperative reporting system for cognitive radio network. In the reporting network, the secondary users forwards the primary user data to the common fusion center (FC). The FC is equipped with linear equalizers and an energy detector to make the decision about the spectrum. The primary user data is considered to be a digital video broadcasting - terrestrial (DVB-T) signal. The sensing channel and the reporting channel is assumed to be an additive white Gaussian noise and an independent identically distributed Raleigh fading respectively. We analyzed the detection probability of MU-MIMO system with linear equalizers and arrived at closed form expression for average detection probability. Also the system performance is investigated under various MIMO scenarios through Monte Carlo simulations