Concept for a power system controller for large space electrical power systems

The development of technology for a fail-operatonal power system controller (PSC) utilizing microprocessor technology for managing the distribution and power processor subsystems of a large multi-kW space electrical power system is discussed. The specific functions which must be performed by the PSC, the best microprocessor available to do the job, and the feasibility, cost savings, and applications of a PSC were determined. A limited function breadboard version of a PSC was developed to demonstrate the concept and potential cost savings

Semantic Object Parsing with Graph LSTM

By taking the semantic object parsing task as an exemplar application scenario, we propose the Graph Long Short-Term Memory (Graph LSTM) network, which is the generalization of LSTM from sequential data or multi-dimensional data to general graph-structured data. Particularly, instead of evenly and fixedly dividing an image to pixels or patches in existing multi-dimensional LSTM structures (e.g., Row, Grid and Diagonal LSTMs), we take each arbitrary-shaped superpixel as a semantically consistent node, and adaptively construct an undirected graph for each image, where the spatial relations of the superpixels are naturally used as edges. Constructed on such an adaptive graph topology, the Graph LSTM is more naturally aligned with the visual patterns in the image (e.g., object boundaries or appearance similarities) and provides a more economical information propagation route. Furthermore, for each optimization step over Graph LSTM, we propose to use a confidence-driven scheme to update the hidden and memory states of nodes progressively till all nodes are updated. In addition, for each node, the forgets gates are adaptively learned to capture different degrees of semantic correlation with neighboring nodes. Comprehensive evaluations on four diverse semantic object parsing datasets well demonstrate the significant superiority of our Graph LSTM over other state-of-the-art solutions.Comment: 18 page

Paper Session II-A - Meteoroid and Orbital Debris Protection for the International Space Station Alpha

The potential for collisions with natural particles (meteoroids) at relative velocities up to 72 km/sec (155,000 mph) has historically been a design consideration for spacecraft. The deposition of man-made particles, referred to as orbital debris, into orbit around the Earth presented an even more severe hypervelocity impact problem for spacecraft designers. This paper examines the threat to the International Space Station Alpha (ISSA) imposed by the meteoroid/orbital debris (M/OD) environment and the risk management approaches implemented to mitigate the threat. The ISSA program has established a balanced strategy for managing the risks associated with the M/OD threat based on the following three principles: 1) maximize design protection by implementing state-of-the-art shielding, 2) track and avoid the larger objects, and 3) minimize residual risk by implementing risk control and abatement features and procedures. Even though NASA is using effective hardware and operational risk mitigation approaches, there remains a residual risk of a penetrating impact. Due to weight, volume, and funding constraints, a gap exists between the passive protection (shielding) capability and active protection (collision avoidance) lower particle size tracking limits. Fortunately, the estimated number of impacts per year decreases exponentially as the size of the particle increases. With the implemented design and planned operational measures, the resulting residual risk of an impact that could potentially cause severe damage to the station is extremely small. Options are continually being assessed and implemented to reduce the residual risk and increase reliability. Control of the debris threat is being pursued by NASA through international treaties and agreements among all space-faring nations. These agreements refer to guidelines for the design, development and operation of satellites with the intent to reduce the evolving orbital debris environment