Dynamic autonomous intelligent control of an asteroid lander

One of the future flagship missions of the European Space Agency (ESA) is the asteroid sample return mission Marco-Polo. Although there have been a number of past missions to asteroids, a sample has never been successfully returned. The return of asteroid regolith to the Earth's surface introduces new technical challenges. This paper develops attitude control algorithms for the descent phase onto an asteroid in micro-gravity conditions and draws a comparison between the algorithms considered. Two studies are also performed regarding the Fault Detection Isolation and Recovery (FDIR) of the control laws considered. The potential of using Direct Adaptive Control (DAC) as a controller for the surface sampling process is also investigated. Use of a DAC controller incorporates increased levels of robustness by allowing realtime variation of control gains. This leads to better response to uncertainties encountered during missions

A validity study of the Flesch readability formula applied to mathematic materials

Thesis (Ed.M.)--Boston Universit

A process-oriented language for describing aspects of reading comprehension

Includes bibliographical references (p. 36-38)The research described herein was supported in part by the National Institute of Education under Contract No. MS-NIE-C-400-76-011

Property in the Moral Life of Human Beings

AbstractLiberal egalitarian political philosophers have often argued that private property is a legal convention dependent on the state and that complaints about taxation from entitlement theorists are therefore based on a conceptual mistake. But our capacity to grasp and use property concepts seems too embedded in human nature for this to be correct. This essay argues that many standard arguments that property is constitutively a legal convention fail, but that the opposition between conventionalists and natural rights theorists is outmoded. In doing this, the essay draws on recent literature in evolutionary biology and psychology. Even though modern property in a complex society involves legal conventions, those conventions should be sensitive to our natural dispositions concerning ownership.</jats:p

Comment on "Correlation between Compact Radio Lout Quasars and Ultrahigh Energy Cosmic Rays"

In a recent paper, Farrar and Biermann argue that there is a strong correlation between the direction of the five highest-energy cosmic-ray events and compact, radio-loud quasars. This Comment shows that this analysis contains several inconsistencies and errors so that the significance of any such correlation is certainly greatly overestimated and perhaps nonexistent.Comment: 2 pages, REVTE

Critical fields and fluctuations determined from specific heat and magnetoresistance in the same nanogram SmFeAs(O,F) single crystal

Through a direct comparison of specific heat and magneto-resistance we critically asses the nature of superconducting fluctuations in the same nano-gram crystal of SmFeAs(O, F). We show that although the superconducting fluctuation contribution to conductivity scales well within the 2D-LLL scheme its predictions contrast the inherently 3D nature of SmFeAs(O, F) in the vicinity T_{c}. Furthermore the transition seen in specific heat cannot be satisfactory described either by the LLL or the XY scaling. Additionally we have validated, through comparing Hc2 values obtained from the entropy conservation construction (Hab=-19.5 T/K and Hab=-2.9 T/K), the analysis of fluctuation contribution to conductivity as a reasonable method for estimating the Hc2 slope

Real, virtual, and other personas in an online collaborative environment

This presentation reports on a study of an unusual online course, which incorporates collaboration across campuses in teaching about evaluation of information technologies. Issues raised by new information technologies are major foci within the course, and also entry points for our study of its implementation.published or submitted for publicationis peer reviewe