Rate determination from vector observations

Vector observations are a common class of attitude data provided by a wide variety of attitude sensors. Attitude determination from vector observations is a well-understood process and numerous algorithms such as the TRIAD algorithm exist. These algorithms require measurement of the line of site (LOS) vector to reference objects and knowledge of the LOS directions in some predetermined reference frame. Once attitude is determined, it is a simple matter to synthesize vehicle rate using some form of lead-lag filter, and then, use it for vehicle stabilization. Many situations arise, however, in which rate knowledge is required but knowledge of the nominal LOS directions are not available. This paper presents two methods for determining spacecraft angular rates from vector observations without a priori knowledge of the vector directions. The first approach uses an extended Kalman filter with a spacecraft dynamic model and a kinematic model representing the motion of the observed LOS vectors. The second approach uses a 'differential' TRIAD algorithm to compute the incremental direction cosine matrix, from which vehicle rate is then derived

Integrated restructurable flight control system demonstration results

The purpose of this study was to examine the complementary capabilities of several restructurable flight control system (RFCS) concepts through the integration of these technologies into a complete system. Performance issues were addressed through a re-examination of RFCS functional requirements, and through a qualitative analysis of the design issues that, if properly addressed during integration, will lead to the highest possible degree of fault-tolerant performance. Software developed under previous phases of this contract and under NAS1-18004 was modified and integrated into a complete RFCS subroutine for NASA's B-737 simulation. The integration of these modules involved the development of methods for dealing with the mismatch between the outputs of the failure detection module and the input requirements of the automatic control system redesign module. The performance of this demonstration system was examined through extensive simulation trials

Numbers and Tempo: 1630-1800

After discussing the role of technology in achieving modern performance standards, this article examines sources that have been cited in support of extremely rapid tempos for the time frame 1630-1800. It summarizes recent findings about the French time devices in which a new source ‒ the Paris dancing master Raoul Auger Feuillet’s reasonable pendulum tempo numbers for dance forms ‒ provides the most accurate information to date for tempo around 1700. Continuing then with other sources cited for rapid tempos, the present article discusses the conflicting statements in Marin Mersenne’s Harmonie universelle and his inaccurate pendulum measurements. It considers the tempo implications of the various time signatures, as supplied, for example, by Jean Rousseau and Jacques Hotteterre, together with Saint-Lambert’s idiomatic use of “une fois plus vite” to indicate the signatures’ tempo relationships. The latter’s “walking man” analogy was not a guide for tempo, but a means to convey beat equality; i.e., sound rhythm. Johann Joachim Quantz’s pulsebeat of 80, unworkable in the tempo sense applied today, was intended to teach fast-to-slow gradations of tempo to musicians who lacked any form of time-measuring device. In response, Daniel Gottlob Türk and Johann George Tromlitz cited the many variables that affect tempo. Without the modern technology that makes extreme tempos possible, tempo in earlier centuries had to have been commensurate with the prevailing conditions

Aggregate Price Effects of Institutional Trading: A Study of Mutual Fund Flow and Market Returns

We study the relation between market returns and aggregate flow into U.S. equity funds, using daily flow data. The concurrent daily relation is positive. Our tests show that this concurrent relation reflects flow and institutional trading affecting returns. This daily relation is similar in magnitude to the price impact reported for an individual institution's trades in a stock. Aggregate flow also follows market returns with a one-day lag. The lagged response of flow suggests either a common response of both returns and flow to new information, or positive feedback trading.

Summer Research Programs Spark Students\u27 Biomedical Interests

No abstract available

A trumpet recital and program notes

LD2668 .R4 MUSC 1987 M37Master of MusicMusic, Theatre, and Danc

Novel Gene Therapy Yields Funding Support

No abstract available

Jefferson Cancer Center Officially Recognized the National Cancer Institute

No abstract available

ASSESSMENT OF THE PRICE IMPACT OF THE SOUTH CAROLINA CUCUMBER MARKETING ORDER

Demand and Price Analysis,