Two-Letter Interjections

It is a curious fact that a substantial percentage of two-letter words are interjections; of the 227 words in the Dictionary of Two-Letter Words issued by the Biliteral Society and reviewed below, grouping interjections according to feelings, commands and statements, show the great variety of messages that can be sent

Origin and evolution of planetary atmospheres

Spacecraft and groundbased observations of the atmospheres of solar system objects have provided a definition of their present characteristics and have yielded clues about their past history. Table 1 presents a summary of our current knowledge of the atmospheric properties of all the planets, except Pluto, and several satellites. The masses of these atmospheres range from the very miniscule values for the Moon, Mercury, and Io, to the more substantial values for the Earth, Venus, Mars, and Titan, to the very large values for the giant planets, where the atmosphere constitutes a significant fraction of the total planetary mass. The compositions of these atmospheres encompass ones dominated by rare gases (the Moon and Mercury), ones containing highly oxidized compounds of carbon, nitrogen, and sulfur (the outer three terrestrial planets and Io), and ones with highly reduced gases (Titan and the giant planets). What factors account for this enormous diversity in properties

Hard and Soft Projects: a framework for analysis

This paper provides clarification on the use of the terms `hard' and `soft' in the context of project and program management, by exploring what it means for a project to be hard or soft. This paper draws on the authors' practice based research into large organisational change programs in a variety of contexts, and the literature on project management, systems thinking and evaluation. A framework for exploring the hardness and softness of project process and outcomes is provided. It acts as an aid to structured discussion and informed decision making about the application of methods for managing projects and programs and the appropriate methods for evaluating their success. This framework is designed to aid in the transfer of lessons learned to practice by offering a common point of comparison between projects, and has potential for use as a predictive aid to resourcing. Its use is demonstrated in three cases

The relation between solar cell flight performance data and materials and manufacturing data Final report

Flight performance data for solar cell power systems in satellites and correlation with manufacturing methods and material

Demonstration of the Zero-Crossing Phasemeter with a LISA Test-bed Interferometer

The Laser Interferometer Space Antenna (LISA) is being designed to detect and study in detail gravitational waves from sources throughout the Universe such as massive black hole binaries. The conceptual formulation of the LISA space-borne gravitational wave detector is now well developed. The interferometric measurements between the sciencecraft remain one of the most important technological and scientific design areas for the mission. Our work has concentrated on developing the interferometric technologies to create a LISA-like optical signal and to measure the phase of that signal using commercially available instruments. One of the most important goals of this research is to demonstrate the LISA phase timing and phase reconstruction for a LISA-like fringe signal, in the case of a high fringe rate and a low signal level. We present current results of a test-bed interferometer designed to produce an optical LISA-like fringe signal previously discussed in the literature.Comment: find minor corrections in the CQG versio

Optical Detection of Blade Flutter

Dynamic strain gages mounted on rotor blades are used as the primary instrumentation for detecting the onset of flutter and defining the vibratory mode and frequency. Optical devices are evaluated for performing the same measurements as well as providing supplementary information on the vibratory characteristics. Two separate methods are studied: stroboscopic imagery of the blade tip and photoelectric scanning of blade tip motion. Both methods give visual data in real time as well as video tape records. The optical systems are described, and representative results are presented. The potential of this instrumentation in flutter research is discussed