Parametric study of the aeroelastic stability of a bearingless rotor

A trade study was conducted to illustrate the sensitivity of the aeroelastic stability of a bearingless main rotor to the rotor hub coupling parameters that are available for the designer. The results are presented over the complete range of rotor speed and collective pitch available and the effects on air resonance of the 6 beam installation angles are compared together with the results of offsetting the cuff snubber attachment. The major part of the study was conducted using the FLAIR analysis which incorporates a uniform representation of the flexbeam. Results are also shown for a modified version of FLAIR in which the uniform beam is replaced by a member having the geometric tailoring resulting from structural optimization

Electron cyclotron thruster new modeling results preparation for initial experiments

The following topics are discussed: a whistler-based electron cyclotron resonance heating (ECRH) thruster; cross-field coupling in the helicon approximation; wave propagation; wave structure; plasma density; wave absorption; the electron distribution function; isothermal and adiabatic plasma flow; ECRH thruster modeling; a PIC code model; electron temperature; electron energy; and initial experimental tests. The discussion is presented in vugraph form

Visitors' Interpretive Strategies at Wolverhampton Art Gallery

Making Meaning in Art Museums is one of two research projects on the theme of art museums and interpretive communities. The first was published as Making Meaning 1:Visitors' Interpretive Strategies at Wolverhampton Art Gallery (RCMG 2001). Making Meaning in Art Museums 2 is the second of two research projects on the theme of art museums and interpretive communities. The Long Gallery at the Nottingham Castle Museum and Art Gallery was selected as the research site for this second study. Both studies have explored the ways in which visitors talked about their experience of a visit to the art museum-both what they said about the paintings and the whole of the visit.The research questions on which this project is based are: What interpretive strategies and repertories are deployed by art museum visitors? Can distinct interpretive communities be identified? What are the implications for the communication policies within art museums? This research is an ethnographic study, using qualitative methods.This research project was funded through a grant from the Arts and Humanities Research Boar

Can Supersymmetry Naturally Explain the Positron Excess?

It has often been suggested that the cosmic positron excess observed by the HEAT experiment could be the consequence of supersymmetric dark matter annihilating in the galactic halo. Although it is well known that evenly distributed dark matter cannot account for the observed excess, if substantial amounts of local dark matter substructure are present, the positron flux would be enhanced, perhaps to the observed magnitude. In this paper, we attempt to identify the nature of the substructure required to match the HEAT data, including the location, size and density of any local dark matter clump(s). Additionally, we attempt to assess the probability of such substructure being present. We find that if the current density of neutralino dark matter is the result of thermal production, very unlikely ($\sim 10^{-4}$ or less) conditions must be present in local substructure to account for the observed excess.Comment: Version accepted by Physical Review

Social Mobility in the United States as a Markov Process

Previous research on intergenerational mobility in income, occupation, or social class as a Markov process typically uses regression models to analyze cross-sectional data. In this paper we draw data from the National Longitudinal Survey of Youth (NLSY) to build Markov transition states, producing a set of stylized facts from these longitudinal data. We derive the probabilities that children will repeat the occupational, educational, or child-raising choices of their parents. This gives us insight into how such lifestyle choices are vertically transmitted from parents to children, and the degree of persistence of these choices over the generations.

Payload/orbiter contamination control requirement study: Computer interface

The MSFC computer facilities, and future plans for them are described relative to characteristics of the various computers as to availability and suitability for processing the contamination program. A listing of the CDC 6000 series and UNIVAC 1108 characteristics is presented so that programming requirements can be compared directly and differences noted

Payload/orbiter contamination control requirement study: Preliminary contamination mission support plan

Progress is reported on the mission support plan and those support activities envisioned to be applicable and necessary during premission and postmission phases of the Spacelab program. The purpose, role, and requirements of the contamination control operations for the first two missions of the Spacelab equipped Space Transportation System are discussed. The organization of the contamination control operation and its relationship to and interfaces with other mission support functions is also discussed. Some specific areas of contamination to be investigated are treated. They are: (1) windows and viewports, (2) experiment equipment, (3) thermal control surfaces, (4) the contaminant induced atmosphere (as differentiated from the normal ambient atmosphere at the orbit altitude), and (5) optical navigation instruments

Assessing Causation in Breast Implant Litigation: The Role of Science Panels

In two recent cases, federal judges appointed panels of scientific experts to help assess conflicting scientific testimony regarding causation of systemic injuries by silicone gel breast implants. This article will describe the circumstances that gave rise to the appointments, the procedures followed in making the appointments and reporting to the courts, and the reactions of the participants in the proceedings