6 research outputs found
NASA Standard GAS Can Satellite
This paper describes a new direction in small low cost spacecraft. This 150 pound satellite provides access to conduct experiments in space on an economical and short term basis. It can be used by commercial as well as scientific institutions. Currently called the XSAT, it was developed by NASA in cooperation with Defense Systems Inc. (DSI) of McLean, Virginia. XSAT provides for experimental payloads up to 50 pounds, 50 watt hours per day, one megabyte data storage, three day command memory and packetized protocol. Structural and thermal designs can handle worst case loads of the STS manned launch vehicle. XSAT can be operated by an experimenter using a personal computer from a ground-based station either locally or over normal telephone lines. An Attitude Control System (ACS) and/or propulsion system is added to XSAT on a mission peculiar basis in order to accommodate the requirements of each specific payload
Incremental QBF Solving
We consider the problem of incrementally solving a sequence of quantified
Boolean formulae (QBF). Incremental solving aims at using information learned
from one formula in the process of solving the next formulae in the sequence.
Based on a general overview of the problem and related challenges, we present
an approach to incremental QBF solving which is application-independent and
hence applicable to QBF encodings of arbitrary problems. We implemented this
approach in our incremental search-based QBF solver DepQBF and report on
implementation details. Experimental results illustrate the potential benefits
of incremental solving in QBF-based workflows.Comment: revision (camera-ready, to appear in the proceedings of CP 2014,
LNCS, Springer
Self‐heating burn‐in pattern generation based on the genetic algorithm incorporated with a BACK‐like procedure
Blocked clause elimination for QBF
Abstract. Quantified Boolean formulas (QBF) provide a powerful framework for encoding problems from various application domains, not least because efficient QBF solvers are available. Despite sophisticated evaluation techniques, the performance of such a solver usually depends on the way a problem is represented. However, the translation to processable QBF encodings is in general not unique and may either introduce variables and clauses not relevant for the solving process or blur information which could be beneficial for the solving process. To deal with both of these issues, preprocessors have been introduced which rewrite a given QBF before it is passed to a solver. In this paper, we present novel preprocessing methods for QBF based on blocked clause elimination (BCE), a technique successfully applied in SAT. Quantified blocked clause elimination (QBCE) allows to simulate various structural preprocessing techniques as BCE in SAT. We have implemented QBCE and extensions of QBCE in the preprocessor bloqqer. In our experiments we show that preprocessing with QBCE reduces formulas substantially and allows us to solve considerable more instances than the previous state-of-the-art.