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Results for “DIGITAL SIMULATION”

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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Speed in Information Processing with a Computer Driven Visual Display in a Real-time Digital Simulation

Information transfer between the operator and computer-generated display systems is an area where the human factors engineer discovers little useful design data relating human performance to system effectiveness. This study utilized a computer-driven, cathode-ray-tube graphic display to quantify human response speed in a sequential information processing task. The performance criteria was response time to sixteen cell elements of a square matrix display. A stimulus signal instruction specified selected cell locations by both row and column identification. An equal probable number code, from one to four, was assigned at random to the sixteen cells of the matrix and correspondingly required one of four, matched keyed-response alternatives. The display format corresponded to a sequence of diagnostic system maintenance events, that enable the operator to verify prime system status, engage backup redundancy for failed subsystem components, and exercise alternate decision-making judgements. The experimental task bypassed the skilled decision-making element and computer processing time, in order to determine a lower bound on the basic response speed for given stimulus/response hardware arrangement.

Kyle, R. G.↗
NASA NTRS1972

Digital simulation and experimental evaluation of the CO2-H(plus) control of pulmonary ventilation

Previous models of the CO2-H(+) control of ventilation have been concerned either with the response to CO2 inhalation, or the response to perfusion of the surface of the medulla with mock cerebrospinal fluid having a high P sub CO2. Simulation of both responses with the same model has not been attempted. The purpose of the present study was two fold; first to develop such a model and, second, to obtain experimental data from human subjects for both developing this model and for evaluating this and future models.

Milhorn, H. T., Jr.↗
NASA NTRS1973

Digital simulation of the serpentuator using MARSYAS

Serpentuator is a serpentine teleoperator device for intravehicular and extravehicular activities in space. The serpentuator is simulated using simulation software system MARSYAS and using the Component-Connection Simulation model and the Direct Simulation model. A comparison of the results for the two cases shows that under identical conditions, simulation execution time in the Component-Connection model case is reduced by a factor of the order of 100. A visual display of the serpentuator positions is obtained using the AMTRAN system on the Datacraft DC 6024 computer.

Singh, S., P.↗
NASA NTRS1975

Digital simulation of V/STOL aircraft for autopilot research

Simulations of V/STOL aircraft for autopilot research were introduced as examples of large scale systems. A hierarchy of simulations was assembled, and a modular organization was given to the simulations. The dynamics of the system were subdivided into translational and rotational degrees of freedom, based on the different frequencies at which significant variations in motion variables, control forces and moments occur in two subsystems. This is the basis of the autopilot partitioning into two smaller control problems.

Cicolani, L. S.↗
NASA NTRS1974

Digital simulation by partitioning and uncoupling the system model

The present work reviews state variable simulation and then proposes a technique for simulation of nonlinear time varying systems by partitioning the system state variable model and uncoupling the resulting subsystem models so that the linear time-invariant ones can be simulated by state variable solution. Computational requirements and computer time are shown to be reduced. The method does, however, introduce an integration error due to the treatment of the intercoupling terms between the subsystems as inputs which are assumed constant over a computation interval. A fictitious sampler is thereby introduced, which is then derived in the form of a state variable error model. The application of this method in a simulation error analysis for a Saturn V attitude control system model and the simulation of a detailed nonlinear, single-axis model of the LST fine pointing control system is described.

Henson, T. F.↗
NASA NTRS1979

Verification and validation of the NASA Terminal Configured Vehicle's /TCV/ Wind Analysis program using real-time digital simulation

NASA's Terminal Configured Vehicle (TCV) program has been established to develop and evaluate aircraft and flight management technology that will benefit conventional takeoff and landing operations in the terminal area. To this end, a process whereby estimates of longitudinal, lateral, and vertical winds are obtained using the present complement of sensors onboard the TCV aircraft (B737-100) is developed. The results of the simulation experiment to verify and validate the TCV B737 Data Merging and Wind Analysis program have shown that the wind analysis algorithms are correct and that very satisfactory estimates of all three wind components are obtained even in the presence of adverse atmospheric conditions and realistic measurement noise. In realistic worst case conditions, wind component errors of the order of + or - 2.0 knots longitudinally, + or - 0.5 knot laterally, and + or - 1.0 knot vertically are to be expected.

Dieudonne, J. E.↗
NASA NTRS1980

Digital simulation of dynamic processes in radiometer systems

The development and application of several computer programs for simulating different classes of microwave radiometers are described. The programs are dynamic in nature, and they may be used to determine the instantaneous behavior of system variables as a function of time. Some of the programs employ random variable models in the simulations so that the statistical nature of the results may be investigated. The programs have been developed to utilize either the Continuous System Modeling Program or the Advanced Continuous System Language. The validity of most of the programs was investigated using statistical tests, and the results show excellent correlation with theoretical predictions. The programs are currently being used in the investigation of new design techniques for microwave radiometers.

Stanley, W. D.↗
NASA NTRS1984

A fast time domain digital simulation technique for power converters - Application to a buck converter with feedforward compensation

Small signal analysis was performed earlier to demonstrate the marked improvement of dynamic properties and stability margins of a switching regulator employing a novel feedforward input filter compensation scheme. A large signal nonlinear recurrent time domain model is presented for the converter to analyse the transient response due to a step input change with and without the presence of the proposed feedforward loop. The results are verified with experimental data.

Kelkar, S. S.↗
NASA NTRS1983

A functional language approach in high-speed digital simulation

A functional programming approach for a multi-microprocessor architecture is presented. The language, based on Backus FP, its intermediate form and the translation process are discussed and illustrated with an example. The approach allows performance analysis to be performed at a high level as an aid in program partitioning.

Ercegovac, M. D.↗
DOE OSTI2016

Real-time digital simulation to improve advanced microgrid design

In this study, there are several ways to address energy reliability concerns during an extended power outage. This can include hardening the energy infrastructure to reduce potential loss of power, adding redundant backup systems with larger fuel tanks, and improving generator reliability through better maintenance. While each is valid, they are often expensive to adequately implement. The traditional emergency power approach for decades has been the use of building-tied emergency generators to start up and supply emergency power until the utility can come back on line. Unfortunately, operational experience from many recent extended power outages has shown that emergency backup generators are often mismatched in size with the building energy load, under-maintained such that their operational reliability is well below expected values, and have insufficient fuel to operate for the entire power outage. Here we describe how energy reliability and security can be enhanced with the use of Advanced Microgrids.

24 POWER TRANSMISSION AND DISTRIBUTION↗
NASA NTRS2023

The Digital Astronaut Simulation

The Digital Astronaut Simulation provides a human biomechanics modeling, simulation, and analysis capability that is enabling spaceflight hardware design to incorporate the human dynamic input early in development cycles as well as characterize performance after prototypes are built. The enhanced toolset includes a modified multibody model, updated motion capture marker sets, and refined methods for scaling and inverse kinematics. These provide increased accuracy for applications in exercise and extravehicular tasks in reduced gravity, especially where upper extremity motion is involved. A core capability highlighted is the calculation of ground reaction forces, moments, and center of pressure based on motion capture. Verification and validation efforts include comparison with force platform measurements.

Human Spaceflight↗
NASA NTRS1981

Using radar image simulation to assess relative geometric distortions inherent in radar imagery

A unique method for observing the relative contributions of backscatter and propagation effects is afforded by radar image simulation. Digital terrain data are used in modeling radar image formation. Backscatter and propagation effects are modeled separately. These are incorporated serially and the image expression of each is noted. Sequences of images are presented illustrating these effects over a range of slopes and angles of incidence. The conclusions reached are that at angles of incidence that are smaller than the average slope of the terrain in a region, propagation phenomena predominate. As the angle of incidence increases beyond this, the radar image portrays an increasingly faithful representation of the backscatter from the ground. It is also demonstrated that digital simulation affords an important tool for evaluating complex interactions between the ground and radar, for training users in radar image interpretation, and for selecting optimum sensor parameters for particular applications.

Kaupp, V. H.↗