19,582 research outputs found
Satellite power systems structures: A 1980 technology status review
The classes of major structural components and constructions utilized were considered. A review of the current (SPS) structure technology status was made. The major issues considered pertinent to SPS structures are: Cost effective construction, construction materials, structural design requirements, stress and dimensional integrity of as-built structures, and predictability of strength and dynamic behavior. The feasibility of passive figure control approach to MPTS flatness, of structure stiffness compatible with MPTS pointing, of passive control through damping, and the feasibility of space fabrication of ultra-large reflector surfaces are also considered. Qualification, model verification, inspection are considered of vital concern
Development of deployable structures for large space platform systems. Volume 1: Executive summary
The preponderance of study effort was devoted toward the deployable platform systems study which culminated in the detailed design of a ground test article for future development testing. This design is representative of a prototype square-truss, single-fold building-block design that can construct deployable platform structures. This prototype design was selected through a comprehensive and traceable selection process applied to eight competitive designs. The selection process compared the competitive designs according to seven major selection criteria, i.e., design versatility, cost, thermal stability, meteoroid impact significance, reliability, performance predictability, and orbiter integration suitability. In support of the foregoing, a materials data base, and platform systems technology development needs were established. An erectable design of an OTV hangar was selected and recommended for further design development. This design was selected from five study-developed competitive single-fold and double-fold designs including hard-shell and inflatable designs. Also, two deployable manned module configurations, i.e., a hard-shell and an inflatable design were each developed to the same requirements as the composite of two Space station baseline habitat modules
Combined electrolysis device and fuel cell and method of operation Patent
Operation method for combined electrolysis device and fuel cell using molten salt to produce power by thermoelectric regeneration mechanis
Improved Algorithms for Radar-based Reconstruction of Asteroid Shapes
We describe our implementation of a global-parameter optimizer and Square
Root Information Filter (SRIF) into the asteroid-modelling software SHAPE. We
compare the performance of our new optimizer with that of the existing
sequential optimizer when operating on various forms of simulated data and
actual asteroid radar data. In all cases, the new implementation performs
substantially better than its predecessor: it converges faster, produces shape
models that are more accurate, and solves for spin axis orientations more
reliably. We discuss potential future changes to improve SHAPE's fitting speed
and accuracy.Comment: 12 pages, 9 figure
Leave No Youth Behind: Opportunities for Congress to Reach Disconnected Youth
This report discusses six programs being considered by the 108th Congress for reauthorization, focusing on policies designed to assist disconnected and at-risk youth. The review seeks to identify how the programs do or do not consider at-risk or disconnected youth ad how such programs might be improved. After an introduction by Alan Houseman, six papers include: "The Adult Education and Family Literacy Act and Disconnected Youth" (Cynthia G. Brown and Andy Hartman); "The Higher Education Act and Disconnected Youth" (Thomas R. Wolanin); "The Individuals with Disabilities Education Act and Disconnected Youth" (Cynthia G Brown and Jennifer Mezey); "The Runaway and Homeless Youth Act and Disconnected Youth" (Bob Reeg); "The Temporary Assistance for Needy Families Program and Disconnected Youth" (Jodie Levin-Epstein); and "The Workforce Investment Act and Disconnected Youth" (Nisha Patel and Steve Savner)
Remembering Brown: A Tribute to John Hope Franklin
On March 27, 2008, the Duke Forum for Law & Social Change and the Office of the Dean co-sponsored a Symposium entitled, “Remembering Brown.” The panelists discussed both their experiences working to desegregate public schools and their perspectives on whether the aspiration of Brown v. Board of Education has been fulfilled
Remembering Brown: A Tribute to John Hope Franklin
On March 27, 2008, the Duke Forum for Law & Social Change and the Office of the Dean co-sponsored a Symposium entitled, “Remembering Brown.” The panelists discussed both their experiences working to desegregate public schools and their perspectives on whether the aspiration of Brown v. Board of Education has been fulfilled
Have Welfare-To-Work Programs Improved Over Time In Putting Welfare Recipients To Work?
Data from 76 experimental welfare-to-work programs conducted in the United States between 1983 and 1998 are used to investigate whether the impacts of such programs on employment had been improving over time and whether specific program features influencing such changes can be identified. Over the period, an increasing percentage of control group members received services similar to those offered to program group members. As a result, differential participation in program service activities between program and control group members decreased steadily over time. This reduction in the net receipt of program services tended to reduce the impact of these programs on employment. However, the negative influence of the reduced incremental services was offset by other factors that resulted in program impacts remaining essentially constant from 1983 to 1998. Suggestions are made for possibly improving program impacts in future experiments.Welfare Programs; Program Evaluation; Employment Behavior of Low-Income Families; Meta Analysis
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