Effects of exercise equipment on the microgravity environment.

Numerous types of exercise equipment have flown on manned space flights to evaluate and maintain crew members' physical condition while on orbit. Vibrations associated with the use of some exercise equipment cause concern among microgravity scientists who are usually looking for a quiescent environment in which to run their experiments. We discuss the impact of aerobic (bicycle ergometer, treadmill) and non-aerobic (resistance devices) exercise on the microgravity environment of the Space Shuttle Orbiters and the Mir Space Station. In general, characteristic vibration disturbances due to ergometer exercise show the pedalling frequency at 2.5 to 3 Hz and the crew members' body rocking side-to-side at about half the pedalling frequency. For treadmill exercise, the footfall frequency on the treadmill platform can be clearly seen in the 1 to 2 Hz range, along with upper harmonics. The use of resistance exercise devices does not typically cause vibrations. Several vibration isolation systems used on the Orbiters and planned for the International Space Station are introduced. Finally, the responses of specific experiments to exercise vibrations are outlined.     

The LDA ? An Integrated Diagnostics Tool

In this paper we describe the Logic Designer's Apprentice (LDA). The LDA is a knowledge-based computer program (an ``expert system') that designs digital electronic circuits. The LDA extends existing CAD/CAE capabilities by providing a computer aid to the design process, supplementing those that assist the drafting, layout, and simulation processes. It seeks to ensure that appropriate testability (and in the future, other ``ility') features are incorporated during the earliest stages of design in accord with the guidelines defined for Integrated Diagnostics. We discuss issues relevant to the engineering development of other knowledge-based tools needed for Integrated Diagnostics including tool selection and choice of knowledge representation.