Frequency characteristics of aerial scenes with respect to a video imagining system

Thesis (M.A.)--Boston UniversityAn overall investigation is made of operating characteristics, theoretical limitations and optimum range values for video communication of aerial scenes. Reasons are given for the selection of a particular receiver and the importance of this type of study is indicated from the A.D.P. crystals' complex A.C. frequency response. The restricted contrast range, due to haze, is noted in evaluating the various video systems

The Invisible Web: A Quick Overview

This article provides a quick overview of recent literature published about the Invisible Web. In particular, this article covers such topics as what is the Invisible Web, weaknesses of popular search engines, types of information found on the Invisible Web, when to use the Invisible Web, search tools and search strategies

Effect of piston bowl geometry on combustion and emissions of a direct injected diesel engine

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.The effect of piston bowl geometry on the performance and exhaust emissions from a modern, high speed direct-injection (HSDI) diesel engine was investigated. Four piston bowl geometry’s (shape) were designed, manufactured and tested in a pre-production HSDI diesel engine installed on an eddy-current dynamometer. A series of experimental tests were performed to determined the optimum injector configuration for each piston bowl shape, the best bowl shape for minimum drive-cycle simulated emissions, and the effect of in-cylinder swirl ratio at various engine operating conditions. Results from computational fluid dynamics (CFD) combustion simulation of extreme injector configurations, correlated well with the experimental trends observed. Full-load testing to determine the optimum injector configuration for each piston bowl shape, indicated that exhaust emissions were very sensitive to the point of fuel impingement on the piston bowl walls. In particular, the trend in the emission of particulates and NOx was explained in relation to the point of fuel impingement, and supported by CFD combustion simulation. The emission of smoke and particulates was found to be dependent on wall wetting and late combustion. Key features for the successful design of future HSDI piston bowl shapes were identified, based on the results form piston bowl comparison tests at a selection of the European drive cycle simulation conditions. The effect in-cylinder swirl ratio on engine performance and emissions was determined. An increase in the rate of mixing and heat release from higher swirl generally raised the emissions of NOx, but reduced smoke formation at low engine speeds. Benefits of an increase in swirl on emissions were negated at high engine speeds due to throttling of the intake charge.This work was financially supported by Ford Motor Company

Advanced materials for space nuclear power systems

The overall philosophy of the research was to develop and characterize new high temperature power conversion and radiator materials and to provide spacecraft designers with material selection options and design information. Research on three candidate materials (carbide strengthened niobium alloy PWC-11 for fuel cladding, graphite fiber reinforced copper matrix composites for heat rejection fins, and tungsten fiber reinforced niobium matrix composites for fuel containment and structural supports considered for space power system applications is discussed. Each of these types of materials offers unique advantages for space power applications