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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,117 records · Page 62
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

Model-based software design

Domain-specific knowledge is required to create specifications, generate code, and understand existing systems. Our approach to automating software design is based on instantiating an application domain model with industry-specific knowledge and then using that model to achieve the operational goals of specification elicitation and verification, reverse engineering, and code generation. Although many different specification models can be created from any particular domain model, each specification model is consistent and correct with respect to the domain model.

Iscoe, Neil↗
NASA NTRS1998

An approach to the design and implementation of spacecraft attitude control systems

Over 39 years and a long list of missions, the guidance, navigation, and control (GN&C) groups at the Goddard Space Flight Center have gradually developed approaches to the design and implementation of successful spacecraft attitude control systems. With the recent creation of the Guidance, Navigation, and Control Center at Goddard, there is a desire to document some of these design practices to help to ensure their consistent application in the future. In this paper, we will discuss the beginnings of this effort, drawing primarily on the experience of one of the past attitude control system (ACS) groups at Goddard (what was formerly known as Code 712, the Guidance, Navigation, and Control Branch). We will discuss the analysis and design methods and criteria used, including guidelines for linear and nonlinear analysis, as well as the use of low- and high-fidelity simulation for system design and verification of performance. Descriptions of typical ACS sensor and actuator hardware will be shown, and typical sensor/actuator suites for a variety of mission types detailed. A description of the software and hardware test effort will be given, along with an attempt to make some qualitative estimates on how much effort is involved. The spacecraft and GN&C subsystem review cycles will be discussed, giving an outline of what design reviews are typically held and what information should be presented at each stage. Finally, we will point out some of the lessons learned at Goddard.

ODonnell, James R., Jr.↗
NASA NTRS1998

An Approach to the Design and Implementation of Spacecraft Attitude Control Systems

Over 39 years and a long list of missions, the guidance, navigation, and control (GN&C) groups at the Goddard Space Flight Center have gradually developed approaches to the design and implementation of successful spacecraft attitude control systems. With the recent creation of the Guidance, Navigation, and Control Center at Goddard, there is a desire to document some of these design practices to help to ensure their consistent application in the future. In this paper, we will discuss the beginnings of this effort, drawing primarily on the experience of one of the past attitude control system (ACS) groups at Goddard (what was formerly known as Code 712, the Guidance, Navigation, and Control Branch). We will discuss the analysis and design methods and criteria used, including guidelines for linear and nonlinear analysis, as well as the use of low- and high-fidelity simulation for system design and verification of performance. Descriptions of typical ACS sensor and actuator hardware will be shown, and typical sensor/actuator suites for a variety of mission types detailed. A description of the software and hardware test effort will be given, along with an attempt to make some qualitative estimates on how much effort is involved. The spacecraft and GN&C subsystem review cycles will be discussed, giving an outline of what design reviews are typically held and .what information should be presented at each stage. Finally, we will point out some of the lessons learned at Goddard.

ODonnell, James R., Jr.↗
NASA NTRS2001

Simulation of MC-1 Engine on Real-Time Station

The MC-1 rocket engine is a new, 60,000-pound-thrust engine designed to boost small spacecraft carrying payloads weighing up to 500 pounds. The engine was designed in-house at NASA's Marshall Space Flight Center (MSFC) in Huntsville, Alabama, and built by SUMMA Technology, Inc. A vital part of the success of the engine development was the verification of the Propulsion System Controller (PSC) used to control the MC-1 engine during development testing at test facilities in Mississippi and California. The MC-1 engine simulation software was developed on the Applied Dynamics, Inc.'s Real-Time Station (RTS) computer system (ESL) to verify the PSC's hardware and software performance in the Marshall Avionics System Testbed's (MAST) Engine Simulation Lab at the MSFC. The engine model includes the simulation of pressure transducers, thermocouple sensors and valve-positions.

Ly, William↗
NASA NTRS2003

An Overview of the Process for Pre-Launch Checkout and Transition Activities in Support of the International Space Station (ISS) Payload Operations Integration Center

The objective of this paper is to provide future ISS scientists and/or engineers with an overview of the coordination process for the preparation and implementation of the pre-launch checkout and transition activities as observed from the Marshall Control Flight Center (MSFC) Payload Operations Integration Center perspective. This includes 4 major phases: (1) Verification and validation of the new command and telemetry databases that are needed for new payload experiments and new onboard formats; (2) Integration testing of the new ground control software and hardware; (3) Final internal and external pre-launch checkouts with cadre and experiment teams; (4) Performance of the actual synchronized transition between MSFC, Johnson Space Center (JSC), and ISS onboard configuration to new onboard software, ground software, and databases.

Digesu, Sam↗
NASA NTRS2007

SPENVIS Implementation of End-of-Life Solar Cell Calculations Using the Displacement Damage Dose Methodology

This paper presents a method for using the SPENVIS on-line computational suite to implement the displacement damage dose (D(sub d)) methodology for calculating end-of-life (EOL) solar cell performance for a specific space mission. This paper builds on our previous work that has validated the D(sub d) methodology against both measured space data [1,2] and calculations performed using the equivalent fluence methodology developed by NASA JPL [3]. For several years, the space solar community has considered general implementation of the D(sub d) method, but no computer program exists to enable this implementation. In a collaborative effort, NRL, NASA and OAI have produced the Solar Array Verification and Analysis Tool (SAVANT) under NASA funding, but this program has not progressed beyond the beta-stage [4]. The SPENVIS suite with the Multi Layered Shielding Simulation Software (MULASSIS) contains all of the necessary components to implement the Dd methodology in a format complementary to that of SAVANT [5]. NRL is currently working with ESA and BIRA to include the Dd method of solar cell EOL calculations as an integral part of SPENVIS. This paper describes how this can be accomplished.

Walters, Robert↗
DOE OSTI2022

Towards Ultra-high-resolution E3SM Land Modeling on Exascale Computers

Here we present an ultra-high-resolution E3SM land model (uELM) for high-fidelity land simulations targeting new Exascale computers. After considering modeling infrastructure compatibility and ELM software features, we designed a parallel model for the uELM development targeting hybrid architectures of new US Exascale computers. We also described a function unit test framework to expedite the piece-wise code porting (with compiler directives), verification, and global variable management. Furthermore, in this study, we report an early uELM model development using OpenACC within a function unit test framework on a pre-Exascale computer, demonstrate the performance of a uLEM submodel with a 3.0-time speedup, and summarize the code porting experience regarding global variable handling, deepcopy, memory reduction, and parallel loop reconstruction.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2014

SU-D-18A-02: Towards Real-Time On-Board Volumetric Image Reconstruction for Intrafraction Target Verification in Radiation Therapy

Purpose: To expedite on-board volumetric image reconstruction from limited-angle kV—MV projections for intrafraction verification. Methods: A limited-angle intrafraction verification (LIVE) system has recently been developed for real-time volumetric verification of moving targets, using limited-angle kV—MV projections. Currently, it is challenged by the intensive computational load of the prior-knowledge-based reconstruction method. To accelerate LIVE, we restructure the software pipeline to make it adaptable to model and algorithm parameter changes, while enabling efficient utilization of rapidly advancing, modern computer architectures. In particular, an innovative two-level parallelization scheme has been designed: At the macroscopic level, data and operations are adaptively partitioned, taking into account algorithmic parameters and the processing capacity or constraints of underlying hardware. The control and data flows of the pipeline are scheduled in such a way as to maximize operation concurrency and minimize total processing time. At the microscopic level, the partitioned functions act as independent modules, operating on data partitions in parallel. Each module is pre-parallelized and optimized for multi-core processors (CPUs) and graphics processing units (GPUs). Results: We present results from a parallel prototype, where most of the controls and module parallelization are carried out via Matlab and its Parallel Computing Toolbox. The reconstruction is 5 times faster on a data-set of twice the size, compared to recently reported results, without compromising on algorithmic optimization control. Conclusion: The prototype implementation and its results have served to assess the efficacy of our system concept. While a production implementation will yield much higher processing rates by approaching full-capacity utilization of CPUs and GPUs, some mutual constraints between algorithmic flow and architecture specifics remain. Based on a careful analysis of the prototype performance, it will be feasible to resolve such issues through appropriate algorithmic modifications or special-purpose hardware, thus enabling target verification in seconds with the LIVE system. This work was partially supported by a research grant from Varian Medical Systems.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2014

Physics based model for online fault detection in autonomous cryogenic loading system

We report the progress in the development of the chilldown model for a rapid cryogenic loading system developed at NASA-Kennedy Space Center. The nontrivial characteristic feature of the analyzed chilldown regime is its active control by dump valves. The two-phase flow model of the chilldown is approximated as one-dimensional homogeneous fluid flow with no slip condition for the interphase velocity. The model is built using commercial SINDA/FLUINT software. The results of numerical predictions are in good agreement with the experimental time traces. The obtained results pave the way to the application of the SINDA/FLUINT model as a verification tool for the design and algorithm development required for autonomous loading operation.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
NASA NTRS1987

A methodology for evaluation of an interactive multispectral image processing system

Because of the considerable cost of an interactive multispectral image processing system, an evaluation of a prospective system should be performed to ascertain if it will be acceptable to the anticipated users. Evaluation of a developmental system indicated that the important system elements include documentation, user friendliness, image processing capabilities, and system services. The criteria and evaluation procedures for these elements are described herein. The following factors contributed to the success of the evaluation of the developmental system: (1) careful review of documentation prior to program development, (2) construction and testing of macromodules representing typical processing scenarios, (3) availability of other image processing systems for referral and verification, and (4) use of testing personnel with an applications perspective and experience with other systems. This evaluation was done in addition to and independently of program testing by the software developers of the system.

Kovalick, William M.↗
NASA NTRS1987

Expert system verification concerns in an operations environment

The Space Shuttle community is currently developing a number of knowledge-based tools, primarily expert systems, to support Space Shuttle operations. It is proposed that anticipating and responding to the requirements of the operations environment will contribute to a rapid and smooth transition of expert systems from development to operations, and that the requirements for verification are critical to this transition. The paper identifies the requirements of expert systems to be used for flight planning and support and compares them to those of existing procedural software used for flight planning and support. It then explores software engineering concepts and methodology that can be used to satisfy these requirements, to aid the transition from development to operations and to support the operations environment during the lifetime of expert systems. Many of these are similar to those used for procedural hardware.

Goodwin, Mary Ann↗
NASA NTRS2002

Component based approach to modeling for model checking

This paper presents a portion of an overall research project on the generation of a software security assessment instrument to aid developers in assessing and assuring the security of software in the development and maintenance lifecycles.

security toolset model checking security safety fo↗
NASA NTRS2013

Physics Based Model for Online Fault Detection in Autonomous Cryogenic Loading System

We report the progress in the development of the chilldown model for rapid cryogenic loading system developed at KSC. The nontrivial characteristic feature of the analyzed chilldown regime is its active control by dump valves. The two-phase flow model of the chilldown is approximated as one-dimensional homogeneous fluid flow with no slip condition for the interphase velocity. The model is built using commercial SINDAFLUINT software. The results of numerical predictions are in good agreement with the experimental time traces. The obtained results pave the way to the application of the SINDAFLUINT model as a verification tool for the design and algorithm development required for autonomous loading operation.

Cryogenics↗
NASA NTRSDate not supplied

From Correct Specifications to Automatically Verified Implementations

Creating formally verified implementations of software can be time-consuming and difficult. This presentation details this process, and the attempts at easing the level of difficulty and human interaction. It begins by discussing the verification of an implementation of the Compact Position Reporting algorithm, which was an involved and manual process, and goes on to show the advances made since.

Mariano M. Moscato↗
DOE OSTI2021

Sensitivity Analysis of MFiX-PIC Parameters Using Nodeworks, PSUADE, and DAKOTA

The study presented in this report was aimed to demonstrate UQ analysis performed not only with Nodeworks, but also two other well-established UQ software tools from the U.S. DOE’s National Laboratories (PSUADE from Lawrence Livermore National Laboratory and DAKOTA from Sandia National Laboratory). It is important to emphasize that the motivation of this study was not to determine the best UQ software, but to verify if the global sensitivity analyses from the end-to-end workflow in Nodeworks are consistent with the results of other two UQ software. The components of Nodeworks from Python’s ecosystem have been tested as standalone libraries. However, an assessment study for the complete workflow targeting a specific UQ analysis has not been performed for Nodeworks. Hence, this study is expected to serve as an equivalent of solution verification for Nodeworks using other established UQ tools as reference solution. For this purpose, three distinct flow configurations (i.e., settling bed, bubbling fluidized, and circulating fluidized bed) have been used as representative multiphase flow problems of interest. The results of the systematic simulation campaigns performed in an earlier study using the particle-in-cell (PIC) approach in the Multiphase Flow with Interphase eXchanges (MFIX) suite of solvers (i.e., MFiX-PIC) was utilized. The same set of tabulated results was provided as input to the different UQ software for global sensitivity analysis. Results for the three cases indicate that based on the Sobol’ Sensitivity Indices method the order of importance ranking determined by Nodeworks for the Sobol’ Total Sensitivity Indices is consistent with PSUADE and DAKOTA in each case for the five model parameters considered. The input files for Nodeworks for the three cases are also shared through NETL’s Gitlab repository for the reader interested in reproducibility and further analysis (See Section 1.2).

97 MATHEMATICS AND COMPUTING↗
NASA NTRSDate not supplied

Seamless Integration of Multibody and Orbital Dynamics to Support Human Spaceflight Simulations

At the NASA Johnson Space Center (JSC), modeling capability requirements are often driven by the need to simulate upcoming mission scenarios for analysis, procedures development, and training. In preparation for free-flyer vehicle capture, maneuvers, and release, it was determined that the multibody dynamics capabilities provided by MBDyn and the orbital dynamics capabilities supplied by JEOD needed to be merged to properly simulate the dynamic behaviors expected on-orbit. After initial attempts to combine the two packages proved cumbersome, it was decided that a more refined solution was required to facilitate the interface between these two packages. The resulting interface software package was named MBJEOD. The primary design goals for this new package were to leave MBDyn and JEOD untouched, to simplify and clarify simulation initialization for users, and to support any topology or on-orbit operational scenario that future missions might require. This paper provides a detailed overview of MBJEOD and the approach taken to seamlessly integrate the multibody dynamics of MBDyn with the orbital dynamics of JEOD. Additional attention is given to the numerical considerations required for MBJEOD and the simplifying assumptions leveraged to provide for real-time simulation needs. Verification and validation are addressed and current MBJEOD applications at the NASA JSC are discussed.

modeling↗
NASA NTRSDate not supplied

Seamless Integration of Multibody and Orbital Dynamics to Support Human Spaceflight Simulations

At the NASA Johnson Space Center (JSC), modeling capability requirements are often driven by the need to simulate upcoming mission scenarios for analysis, procedures development, and training. In preparation for free-flyer vehicle capture, maneuvers, and release, it was determined that the multibody dynamics capabilities provided by MBDyn and the orbital dynamics capabilities supplied by JEOD needed to be merged to properly simulate the dynamic behaviors expected on-orbit. After initial attempts to combine the two packages proved cumbersome, it was decided that a more refined solution was required to facilitate the interface between these two packages. The resulting interface software package was named MBJEOD. The primary design goals for this new package were to leave MBDyn and JEOD untouched, to simplify and clarify simulation initialization for users, and to support any topology or on-orbit operational scenario that future missions might require. This paper provides a detailed overview of MBJEOD and the approach taken to seamlessly integrate the multibody dynamics of MBDyn with the orbital dynamics of JEOD. Additional attention is given to the numerical considerations required for MBJEOD and the simplifying assumptions leveraged to provide for real-time simulation needs. Verification and validation are addressed and current MBJEOD applications at the NASA JSC are discussed.

modeling↗