Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “PERFORMANCE PREDICTION”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
DOE OSTI2012

Modeling and Predicting Performance of High Performance Computing Applications on Hardware Accelerators

Computers with hardware accelerators, also referred to as hybrid-core systems, speedup applications by offloading certain compute operations that can run faster on accelerators. Thus, it is not surprising that many of top500 supercomputers use accelerators. However, in addition to procurement cost, significant programming and porting effort is required to realize the potential benefit of such accelerators. Hence, before building such a system it is prudent to answer the question 'what is the projected performance benefit from accelerators for the workloads of interest?'. We address this question by way of a performance-modeling framework that predicts realizable application performance on accelerators rapidly and accurately without going to the considerable effort of porting and tuning. The modeling framework first automatically identifies commonly found compute patterns in scientific applications which we term idioms, which may benefit by accelerator technology. Next the framework models the predicted speedup of those idioms if they were to be ported to and run on hardware accelerators. As a proof of concept we characterize two kinds of accelerators 1) the FPGA accelerators on a Convey HC-1 system and 2) an NVIDIA FERMI GPU accelerator. We model performance of the idioms gather/scatter and stream and our predictions show that where these occur in two full-scale HPC applications, Milc and HYCOM, gather/scatter speeds up by as much as 15X, and stream by as much as 14X, whereas the overall compute time of Milc improves by 3.4% and HYCOM by 20%.

Computer Science↗
NASA NTRS2022

MSL MMRTG Power Modeling for Lifetime Performance Predictions

The Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) has been providing power to the Mars Science Laboratory (MSL) rover, Curiosity, for surface operations since 2012. The Jet Propulsion Laboratory (JPL) has employed the Life Performance Prediction Model (LPPM) to generate predictions and outputs based upon flight data from the rover and experimental data from the thermoelectric (TE) couples. In order to make these predictions, LPPM requires various spacecraft inputs relevant to RTG performance such as fin root temperature, load voltage, general purpose heat source (GPHS) inventory, etc., combined with couple data such as thermoelectric properties, interface degradation, and sublimation properties. With tens of thousands of hours of flight data to date, LPPM can not only track performance to date, but also make predictions on the power output of the MMRTG through the 17-year end-of-design-life (EODL). These predictions are useful for mission planners and surface operators who rely on the MMRTG for power in order to perform the critical science necessary during the mission. This paper will showcase the power data extracted from the flight electronics, comparing it to the predictions and outputs generated from LPPM.

Pinkowski, Stanley↗
NASA NTRS1997

Predicted Performance of a Thrust-Enhanced SR-71 Aircraft with an External Payload

NASA Dryden Flight Research Center has completed a preliminary performance analysis of the SR-71 aircraft for use as a launch platform for high-speed research vehicles and for carrying captive experimental packages to high altitude and Mach number conditions. Externally mounted research platforms can significantly increase drag, limiting test time and, in extreme cases, prohibiting penetration through the high-drag, transonic flight regime. To provide supplemental SR-71 acceleration, methods have been developed that could increase the thrust of the J58 turbojet engines. These methods include temperature and speed increases and augmentor nitrous oxide injection. The thrust-enhanced engines would allow the SR-71 aircraft to carry higher drag research platforms than it could without enhancement. This paper presents predicted SR-71 performance with and without enhanced engines. A modified climb-dive technique is shown to reduce fuel consumption when flying through the transonic flight regime with a large external payload. Estimates are included of the maximum platform drag profiles with which the aircraft could still complete a high-speed research mission. In this case, enhancement was found to increase the SR-71 payload drag capability by 25 percent. The thrust enhancement techniques and performance prediction methodology are described.

Conners, Timothy R.↗
NASA NTRS2003

Navier-Stokes and Comprehensive Analysis Performance Predictions of the NREL Phase VI Experiment

A vortex lattice code, CAMRAD II, and a Reynolds-Averaged Navier-Stoke code, OVERFLOW-D2, were used to predict the aerodynamic performance of a two-bladed horizontal axis wind turbine. All computations were compared with experimental data that was collected at the NASA Ames Research Center 80- by 120-Foot Wind Tunnel. Computations were performed for both axial as well as yawed operating conditions. Various stall delay models and dynamics stall models were used by the CAMRAD II code. Comparisons between the experimental data and computed aerodynamic loads show that the OVERFLOW-D2 code can accurately predict the power and spanwise loading of a wind turbine rotor.

NREL (NATIONAL RENEWABLE ENERGY LABORATORY)↗
DOE OSTI2021

Comparing Retrofit Wall Performance Predicted from Hygrothermal Simulations to Measurements

Over the past few years ORNL has been showing that WUFI® can be used to predict the moisture performance of walls when exposed to diffusion of water vapor, convection of moist air through the wall, and solar driven moisture. This is accomplished by comparing the hygrothermal simulation results to carefully instruments walls exposed to these phenomena in a climate chamber. In FY 2018, three stick-built walls were succumbed to typical Chicago, Illinois weather conditions in Oak Ridge National Laboratory’s Heat, Air and Moisture chamber. The measured temperature, relative humidity, and moisture content within these walls were compared with WUFI hygrothermal simulation results. In FY 2019, similar experiments and comparisons with WUFI results were completed with two walls, a structural insulated panel-based wall and a concrete masonry unit-based wall. In FY 2020, experiments were completed for a probable exterior retrofit of a wall which included adding cavity and continuous insulation. Two pairs of walls were tested by exposing them to Chicago winter weather with a positive pressure pushing outside air into the wall. The results from the FY 2020 experiments are reported here.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
NASA NTRS1979

Traction drive performance prediction for the Johnson and Tevaarwerk traction model

The fluid rheology model is used to investigate the traction behavior for typical traction drive contacts. The aspect ratio of the contact and the invariably present spin are investigated. Contacts with a low aspect ratio predict a superior performance in that they show less slip for the same degree of traction. Spin always has a diminishing effect on the traction at the same slip. At sufficiently high spin the model may be simplified to a limiting shear stress model. The conventional rigid plastic analysis applies here equally well.

Tevaarwerk, J. L.↗
NASA NTRS1999

Video Guidance Sensor: Optical Performance Predictions and Results from STS-95 Experiment

The Video Guidance Sensor is a key component of NASA's Automated Rendezvous & Capture Program. The Video Guidance Sensor Uses laser illumination of a passive target in the field of view of an on-board camera and signal processor to determine the relative position and attitude between the target and sensor. The Video Guidance Sensor flew on space shuttle mission STS-95 in November of 1998 and was a marked success. Comparisons of experimental results from that mission and theoretical models predicting the optical performance will be discussed.

Jackson, John L.↗
NASA NTRSDate not supplied

Design and Predicted Performance of 4-m Baseline Habitable-Zone Exoplanet Observatory Telescope

The Habitable Exoplanet Observatory Mission (HabEx) is one of four missions which NASA is studying. Its goal is to directly image and spectroscopically characterize planets in the habitable zone around nearby sun-like stars. Additionally, HabEx would perform a broad range of general astrophysics science enabled by 115 to 1700 nm spectral range and 3x3 arc-minute FOV instruments. Critical to achieving its science goals is a large, ultra-stable UV/Optical/Near-IR (UVOIR) telescope. The baseline HabEx telescope is a 4-meter off-axis unobscured three-mirror-anastigmatic, diffraction limited at 400 nm with wavefront stability on the order of a few 10s of picometers. This paper summarizes how science driven systems engineering (using science requirements to derive engineering specifications) resulting in the opto-mechanical design of the HabEx baseline optical telescope assembly. And, how Structural Thermal Optical Performance (STOP) modeling predicts tolerance compliance.

H Philip Stahl↗
NASA NTRS1984

Rotary-wing aerodynamics. Volume 1 - Basic theories of rotor aerodynamics (With application to helicopters). Volume 2 Performance prediction of helicopters (2nd revised and enlarged edition)

Basic theories of rotor aerodynamics are presented and applied to the performance prediction of helicopters. The very simple physicomathematical model of the rotor offered by momentum theory is addressed first, followed by the combined blade-element and momentum theory. Vortex theory is discussed, and a rotor blade is modeled by means of a vortex filament or vorticity surface. Considerations of airfoil sections suitable for rotors are examined. Detailed performance techniques for a single-rotor helicopter in hover, vertical ascent, and forward flight are described, and winged and tandem-rotor helicopter performance calculations are presented as extensions and modifications of single-rotor methodology. Computer data based on the vortex theory are compared with approximate results obtained from the simplified momentum theory and the blade element solution.

Stepniewski, W. Z.↗