Recovery of spinning satellites

The behavior of a space tug and a spinning satellite in a coupled configuration was simulated and analyzed. A docking concept was developed to investigate the requirements pertaining to the design of a docking interface. Sensing techniques and control requirements for the chase vehicle were studied to assess the feasibility of an automatic docking. The effects of nutation dampers and liquid propellant slosh motion upon the docking transient were investigated

Penelope: The NBTI-aware processor

Transistors consist of lower number of atoms with every technology generation. Such atoms may be displaced due to the stress caused by high temperature, frequency and current, leading to failures. NBTI (negative bias temperature instability) is one of the most important sources of failure affecting transistors. NBTI degrades PMOS transistors whenever the voltage at the gate is negative (logic inputPeer ReviewedPostprint (published version

Parametric study of two planar high power flexible solar array concepts

The design parameters examined were: frequency, aspect ratio, packaging constraints, and array blanket flatness. Specific power-to-mass ratios for both solar arrays as a function of array frequency and array width were developed and plotted. Summaries of the baseline design data, developed equations, the computer program operation, plots of the parameters, and the process for using the information as a design manual are presented

Energy and performance models for clocked and asynchronous communication

Journal ArticleParameterized first-order models for throughput, energy, and bandwidth are presented in this paper. Models are developed for many common pipeline methodologies, including clocked flopped, clocked time-borrowing latch protocols, asynchronous two-cycle, four-cycle, delay-insensitive, and source synchronous. The paper focuses on communication costs which have the potential to throttle design performance as scaling continues. The models can also be applied to logic. The equations share common parameters to allow apples-to-apples comparisons against different design targets and pipeline methodologies. By applying the parameters to various design targets, one can determine when unclocked communication is superior at the physical level to clocked communication in terms of energy for a given bandwidth. Comparisons between protocols at fixed targets also allow designers to understand tradeoffs between implementations that have a varying degree of timing assumptions and design requirements

Thermal distortion analysis of the space station solar dynamic concentrator

A method was developed to evaluate the thermal distortion of the Space Station Solar Dynamic Concentrator and the effects of thermal distortion on concentrator optical performance. The analytical method includes generating temperature distributions with TRASYS and SINDA models, interfacing the SINDA results with the SINDA-NASTRAN Interface Program (SNIP), calculating thermal distortion with a NASTRAN/PATRAN finite element model, and providing flux distribution maps within the receiver with the ray tracing OFFSET program. Temperature distributions, thermally induced slope errors, and flux distribution maps within the receiver are discussed. Results during a typical orbit indicate that temperatures of the hexagonal panels and triangular facets range between -18 and 99 C (-1 to 210 F), facet rotations are less than 0.2 mrad, and a change in facet radius due to thermal flattening is less than 5 percent. The predicted power loss with thermal distortion effects was less than 0.3 percent. The thermal distortion of the Solar Dynamic concentrator has negligible effect on the flux distribution within the receiver cavity

Design of the Annular Suspension and Pointing System (ASPS) (including design addendum)

The Annular Suspension and Pointing System is an experiment pointing mount designed for extremely precise 3 axis orientation of shuttle experiments. It utilizes actively controlled magnetic bearing to provide noncontacting vernier pointing and translational isolation of the experiment. The design of the system is presented and analyzed