Guidance and dispersion studies of National Launch System ascent trajectories

Hanson, John M.; Shrader, M. Wade; Chang, Ho-Pen; Freeman, Scott E.

doi:10.2514/6.1992-4306

Cited by 2 publications

(4 citation statements)

References 3 publications

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“…These systems include the flow-dynamics model of the space shuttle main rocket (Hanson et al 1992), the national launch system (Wells et al 1997), and a six-degree-of-freedom robot simulation (Otter et al 1996). Information such as the number of tasks, the precedence-relationship edge density, and the average task complexity were determined by examining the major frame task structures and profiling existing simulations when they were encoded in software and executed on an instruction set processor.…”

Section: Synthetic Task-system Generation and Scheduling-methodology mentioning

confidence: 99%

“…These values all fall within the range of the three real-world task systems that were examined previously with measured edge densities from 0.05 to 0.10 (Hanson et al 1992, Wells et al 1997, Otter et al 1996. For each value of , two task systems were generated by varying the seed of the random-number generator.…”

Section: Search/scheduling Strategy Comparisonmentioning

confidence: 99%

“…This is because the average task will have a higher probability of having more predecessor tasks that have to appear before it in the schedule. Most task systems are sparse in nature, having values of less than 0.1 for graphs with 100 or more tasks (Hanson et al 1992, Wells et al 1997, Otter et al 1996. For each task system created, tasks should also be assigned synthetically-generated execution times for each functional unit in the hardware library.…”

Section: Synthetic Task System Generationmentioning

confidence: 99%

See 2 more Smart Citations

Task Scheduling in a Finite-Resource, Reconfigurable Hardware/Software Codesign Environment

Loo

Wells

2006

INFORMS Journal on Computing

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This paper describes how static task-scheduling methods using stochastic search techniques can be applied to digital systems that are composed entirely of reconfigurable hardware. Such reconfigurable hardware is characterized by the property that its low-level logical functionality is not determined at the time of manufacture, but rather that this functionality becomes set only shortly before or during the invocation of the targeted application. The purpose of this paper is to introduce the basic framework for applying static scheduling theory to arbitrarily-structured task systems targeted to be implemented in prefabricated resource-constrained reconfigurable hardware. The paper also describes initial solutions to this heterogeneous task-scheduling problem that combine a distributed list-based scheduling technique with three probabilistic search strategies. The techniques introduced produce detailed task scheduling and high-level hardware configuration information that can serve as inputs to the software and reconfigurable hardware design automation tools used in the hardware/software codesign process

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Section: Synthetic Task-system Generation and Scheduling-methodology mentioning

confidence: 99%

Section: Search/scheduling Strategy Comparisonmentioning

confidence: 99%

Section: Synthetic Task System Generationmentioning

confidence: 99%

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Task Scheduling in a Finite-Resource, Reconfigurable Hardware/Software Codesign Environment

Loo

Wells

2006

INFORMS Journal on Computing

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“…The first structure which was considered is based upon a simulation of NASA's proposed National Launch System (NLS) [16]. The NLS simulation is a real-time guidance and control type simulation of the U.S. heavy launch vehicle which was proposed in the early 1990's.…”

Section: Analysis For Real-world Structuresmentioning

confidence: 99%

Highly Constrained Task Scheduling on Multiprocessing Systems

2007

Journal of the ACS Advances in Computer Science

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The problem of non-preemptively scheduling a set of m tasks on n processors with communication overhead subject to precedence, memory and deadline constraints is considered. A new heuristic with the time complexity of 0(m 2 n), Augmented Least Space-Time First (LSTF), is proposed to minimize the maximum tardiness. The efficiency of the augmented LSTF using a large number of randomly-generated graphs and three real-world structures is compared with that of the augmented Earliest Deadline First-Earliest Task First (EDF-E) that schedules each ready task on the processor at which it can be scheduled at the earliest time and with that of EDF-R that select the processor at random. The result of the comparisons, which are based on the maximum tardiness and the number of tasks that miss their deadlines, indicates that the augmented LSTF outperforms both EDF-E and EDF-R.

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Guidance and dispersion studies of National Launch System ascent trajectories

Cited by 2 publications

References 3 publications

Task Scheduling in a Finite-Resource, Reconfigurable Hardware/Software Codesign Environment

Task Scheduling in a Finite-Resource, Reconfigurable Hardware/Software Codesign Environment

Highly Constrained Task Scheduling on Multiprocessing Systems

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