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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 685 records · Page 38
All sourcesNASA NTRSDOE OSTI
NASA NTRS1994

Design of a cooperative problem-solving system for en-route flight planning: An empirical evaluation

Both optimization techniques and expert systems technologies are popular approaches for developing tools to assist in complex problem-solving tasks. Because of the underlying complexity of many such tasks, however, the models of the world implicitly or explicitly embedded in such tools are often incomplete and the problem-solving methods fallible. The result can be 'brittleness' in situations that were not anticipated by the system designers. To deal with this weakness, it has been suggested that 'cooperative' rather than 'automated' problem-solving systems be designed. Such cooperative systems are proposed to explicitly enhance the collaboration of the person (or a group of people) and the computer system. This study evaluates the impact of alternative design concepts on the performance of 30 airline pilots interacting with such a cooperative system designed to support en-route flight planning. The results clearly demonstrate that different system design concepts can strongly influence the cognitive processes and resultant performances of users. Based on think-aloud protocols, cognitive models are proposed to account for how features of the computer system interacted with specific types of scenarios to influence exploration and decision making by the pilots. The results are then used to develop recommendations for guiding the design of cooperative systems.

Layton, Charles↗
NASA NTRS1994

Design of a cooperative problem-solving system for en-route flight planning: An empirical evaluation

Both optimization techniques and expert systems technologies are popular approaches for developing tools to assist in complex problem-solving tasks. Because of the underlying complexity of many such tasks, however, the models of the world implicitly or explicitly embedded in such tools are often incomplete and the problem-solving methods fallible. The result can be 'brittleness' in situations that were not anticipated by the system designers. To deal with this weakness, it has been suggested that 'cooperative' rather than 'automated' problem-solving systems be designed. Such cooperative systems are proposed to explicitly enhance the collaboration of the person (or a group of people) and the computer system. This study evaluates the impact of alternative design concepts on the performance of 30 airline pilots interacting with such a cooperative system designed to support enroute flight planning. The results clearly demonstrate that different system design concepts can strongly influence the cognitive processes and resultant performances of users. Based on think-aloud protocols, cognitive models are proposed to account for how features of the computer system interacted with specific types of scenarios to influence exploration and decision making by the pilots. The results are then used to develop recommendations for guiding the design of cooperative systems.

Layton, Charles↗
NASA NTRS1996

Continued Development of Expert System Tools for NPSS Engine Diagnostics

The objectives of this grant were to work with previously developed NPSS (Numerical Propulsion System Simulation) tools and enhance their functionality; explore similar AI systems; and work with the High Performance Computing Communication (HPCC) K-12 program. Activities for this reporting period are briefly summarized and a paper addressing the implementation, monitoring and zooming in a distributed jet engine simulation is included as an attachment.

Lewandowski, Henry↗
NASA NTRS1999

BIO-Plex Information System Concept

This paper describes a suggested design for an integrated information system for the proposed BIO-Plex (Bioregenerative Planetary Life Support Systems Test Complex) at Johnson Space Center (JSC), including distributed control systems, central control, networks, database servers, personal computers and workstations, applications software, and external communications. The system will have an open commercial computing and networking, architecture. The network will provide automatic real-time transfer of information to database server computers which perform data collection and validation. This information system will support integrated, data sharing applications for everything, from system alarms to management summaries. Most existing complex process control systems have information gaps between the different real time subsystems, between these subsystems and central controller, between the central controller and system level planning and analysis application software, and between the system level applications and management overview reporting. An integrated information system is vitally necessary as the basis for the integration of planning, scheduling, modeling, monitoring, and control, which will allow improved monitoring and control based on timely, accurate and complete data. Data describing the system configuration and the real time processes can be collected, checked and reconciled, analyzed and stored in database servers that can be accessed by all applications. The required technology is available. The only opportunity to design a distributed, nonredundant, integrated system is before it is built. Retrofit is extremely difficult and costly.

Jones, Harry↗
NASA NTRS1993

NASA Tech Briefs, December 1993

Topics covered include: High-Performance Computing; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery/Automation; Manufacturing/Fabrication; Mathematics and Information Sciences; Life Sciences; Books and Reports.

Source record↗
NASA NTRS2011

Human factors process failure modes and effects analysis (HF PFMEA) software tool

Methods, computer-readable media, and systems for automatically performing Human Factors Process Failure Modes and Effects Analysis for a process are provided. At least one task involved in a process is identified, where the task includes at least one human activity. The human activity is described using at least one verb. A human error potentially resulting from the human activity is automatically identified, the human error is related to the verb used in describing the task. A likelihood of occurrence, detection, and correction of the human error is identified. The severity of the effect of the human error is identified. The likelihood of occurrence, and the severity of the risk of potential harm is identified. The risk of potential harm is compared with a risk threshold to identify the appropriateness of corrective measures.

Chandler, Faith T.↗
NASA NTRS2011

Design and Measurements of Dual-Polarized Wideband Constant-Beamwidth Quadruple-Ridged Flared Horn

A quad-ridged, flared horn achieving nearly constant beamwidth and excellent return loss over a 6:1 frequency bandwidth is presented. Radiation pattern measurements show excellent beamwidth stability from 2 to 12 GHz. Measured return loss is > 10 dB over the entire band and > 15 dB from 2.5 to 11 GHz. Using a custom physical optics code, system performance of a radio telescope is computed and predicted performance is average 70% aperture efficiency and 10 Kelvin of antenna noise temperature.

decade bandwidth↗
NASA NTRS2016

Thermal Ablation Modeling for Silicate Materials

A general thermal ablation model for silicates is proposed. The model includes the mass losses through the balance between evaporation and condensation, and through the moving molten layer driven by surface shear force and pressure gradient. This model can be applied in the ablation simulation of the meteoroid and the glassy ablator for spacecraft Thermal Protection Systems. Time-dependent axisymmetric computations are performed by coupling the fluid dynamics code, Data-Parallel Line Relaxation program, with the material response code, Two-dimensional Implicit Thermal Ablation simulation program, to predict the mass lost rates and shape change. The predicted mass loss rates will be compared with available data for model validation, and parametric studies will also be performed for meteoroid earth entry conditions.

Ablation↗
NASA NTRS2016

Wave Amplitude Dependent Engineering Model of Propellant Slosh in Spherical Tanks

Liquid propellant slosh is often a concern for the controllability of flight vehicles. Anti-slosh devices are traditionally included in propellant tank designs to limit the amount of sloshing allowed during flight. These devices and any necessary supports can be quite heavy to meet various structural requirements. Some of the burden on anti-slosh devices can be relieved by exploiting the nonlinear behavior of slosh waves in bare smooth wall tanks. A nonlinear regime slosh model for bare spherical tanks was developed through a joint analytical and experimental effort by NASA/MSFC. The developed slosh model accounts for the large damping inherent in nonlinear slosh waves which is more accurate and drives conservatism from vehicle stability analyses that use traditional bare tank slosh models. A more accurate slosh model will result in more realistic predicted slosh forces during flight reducing or removing the need for active controls during a maneuver or baffles in the tank design. Lower control gains and smaller or fewer tank baffles can reduce cost and system complexity while increasing vehicle performance. Both Computational Fluid Dynamics (CFD) simulation and slosh testing of three different spherical tank geometries were performed to develop the proposed slosh model. Several important findings were made during this effort in addition to determining the parameters to the nonlinear regime slosh model. The linear regime slosh damping trend for spherical tanks reported in NASA SP-106 was shown to be inaccurate for certain regions of a tank. Additionally, transition to the nonlinear regime for spherical tanks was only found to occur at very large wave amplitudes in the lower hemisphere and was a strong function of the propellant fill level in the upper hemisphere. The nonlinear regime damping trend was also found to be a function of the propellant fill level.

Brodnick, Jacob↗
DOE OSTI2025

Early Research in Load-Following Management for HPC-Nuclear Integration

With the rising demand for high performance computing (HPC) and artificial intelligence (AI) systems, maintaining a stable and efficient power supply is increasingly critical. The HPC team at Idaho National Laboratory is spearheading efforts to seamlessly integrate HPC systems with nuclear reactors. This lightning talk explores one early strategy for managing power fluctuations using software-defined controls. To effectively harness nuclear reactors for power generation, control mechanisms are essential to address the slow load-following capabilities of reactors, which are typically around 5% per minute. While this rate is sufficient for many uses, large HPC systems can experience rapid power consumption changes by tens of megawatts when jobs start or stop running. A reactor could overproduce power and match the peak power rating for the HPC system, however when the system is not running a job or a job unexpectedly stops, the load-following of the system would be affected leading to power being wasted and the likelihood of power transient occurrences increases. Controlling the increase or decrease of power consumption on these systems at the same rate as the load-following of reactors is one piece of the puzzle to properly utilizing nuclear reactors as a power source for HPC systems.

97 - MATHEMATICS AND COMPUTING↗
NASA NTRS1979

Navigation-aid power systems

Design synthesis and performance analysis (DSPA) program package is collection of subroutines used for computation of design and performance characteristics of viable solar-array-charged battery powered system for flashing-lamp buoys employed as maritime aids to navigation.

Goltz, G. L.↗
NASA NTRS2017

Development of an Active Flow Control Technique for an Airplane High-Lift Configuration

This study focuses on Active Flow Control methods used in conjunction with airplane high-lift systems. The project is motivated by the simplified high-lift system, which offers enhanced airplane performance compared to conventional high-lift systems. Computational simulations are used to guide the implementation of preferred flow control methods, which require a fluidic supply. It is first demonstrated that flow control applied to a high-lift configuration that consists of simple hinge flaps is capable of attaining the performance of the conventional high-lift counterpart. A set of flow control techniques has been subsequently considered to identify promising candidates, where the central requirement is that the mass flow for actuation has to be within available resources onboard. The flow control methods are based on constant blowing, fluidic oscillators, and traverse actuation. The simulations indicate that the traverse actuation offers a substantial reduction in required mass flow, and it is especially effective when the frequency of actuation is consistent with the characteristic time scale of the flow.

Shmilovich, Arvin↗
NASA NTRS1993

Computer simulation of a 20-kHz power system for advanced launch systems

The performance of two 20-kHz actuator power systems being built for an advanced launch system are evaluated for typical launch senario using an end-to-end system simulation. Aspects of system performance ranging from the switching of the power electronic devices to the vehicle aerodynamics are represented in the simulation. It is shown that both systems adequately stabilize the vehicle against a wind gust during launch. However, it is also shown that in both cases there are bus voltage and current fluctuations which make system power quality a concern.

Sudhoff, S. D.↗
NASA NTRS2005

Heart Pump Design for Cleveland Clinic Foundation

Through a Lewis CommTech Program project with the Cleveland Clinic Foundation, the NASA Lewis Research Center is playing a key role in the design and development of a permanently implantable, artificial heart pump assist device. Known as the Innovative Ventricular Assist System (IVAS), this device will take on the pumping role of the damaged left ventricle of the heart. The key part of the IVAS is a nonpulsatile (continuous flow) artificial heart pump with centrifugal impeller blades, driven by an electric motor. Lewis is part of an industry and academia team, led by the Ohio Aerospace Institute (OAI), that is working with the Cleveland Clinic Foundation to make IVAS a reality. This device has the potential to save tens of thousands of lives each year, since 80 percent of heart attack victims suffer irreversible damage to the left ventricle, the part of the heart that does most of the pumping. Impeller blade design codes and flow-modeling analytical codes will be used in the project. These codes were developed at Lewis for the aerospace industry but will be applicable to the IVAS design project. The analytical codes, which currently simulate the flow through the compressor and pump systems, will be used to simulate the flow within the blood pump in the artificial heart assist device. The Interdisciplinary Technology Office heads up Lewis' efforts in the IVAS project. With the aid of numerical modeling, the blood pump will address many design issues, including some fluid-dynamic design considerations that are unique to the properties of blood. Some of the issues that will be addressed in the design process include hemolysis, deposition, recirculation, pump efficiency, rotor thrust balance, and bearing lubrication. Optimum pumping system performance will be achieved by modeling all the interactions between the pump components. The interactions can be multidisciplinary and, therefore, are influenced not only by the fluid dynamics of adjacent components but also by thermal and structural effects. Lewis-developed flow-modeling codes to be used in the pump simulations will include a one-dimensional code and an incompressible three-dimensional Navier-Stokes flow code. These codes will analyze the prototype pump designed by the Cleveland Clinic Foundation. With an improved understanding of the flow phenomena within the prototype pump, design changes to improve the performance of the pump system can be verified by computer prior to fabrication in order to reduce risks. The use of Lewis flow modeling codes during the design and development process will improve pump system performance and reduce the number of prototypes built in the development phase. The first phase of the IVAS project is to fully develop the prototype in a laboratory environment that uses a water/glycerin mixture as the surrogate fluid to simulate blood. A later phase of the project will include testing in animals for final validation. Lewis will be involved in the IVAS project for 3 to 5 years.

Source record↗
DOE OSTI2026

Elevating SolTrace's Capabilities for the Next Generation of Concentrating Solar Analysis

SolTrace is an open-source Monte Carlo ray tracing software developed at NREL. SolTrace can characterize concentrating solar thermal (CST) collector optical performance and is CST technology agnostic. Shown in Fig. 1, SolTrace is a foundational tool in NREL's CST system and component modeling suite. SolTrace's generic surface elements can flexibly model novel collector and receiver designs to predict spatial and temporal flux distributions - critical to understand for CST component design, performance prediction, and system integration. Since its initial development, SolTrace has over 1,650 references on Google Scholar, over 9,800 downloads since 2017, and has served the CST research and development community as a benchmark of 3rd party verification. SolTrace provides users with many options for defining surface shape and boundaries. However, SolTrace provides limited documentation which can result in a steep learning curve for new users. Additionally, SolTrace lacks the computational performance required to evaluate optical performance of a CST system over the course of a year and/or iteratively over design parameters in a timely manner. To address this, we are working towards a new release of SolTrace that enables increased computational throughput by implementing ray tracing acceleration structures and enabling GPU parallelization. Additionally, we are working to improve SolTrace's usability, accessibility, and maintainability by (1) automating solar position time-dependent simulation processes, (2) creating general CST collector templates of grouped elements, (3) updating the user interface to better visualize model inputs and outputs, and (4) creating a user support network through forums, "how to" videos, and documentation.

14 SOLAR ENERGY↗
NASA NTRS1984

Report of the Panel on Guidance, Navigation, and Control

Guidance, navigation, and control (GNC) systems have historically been vital to improving operational capability of aircraft. The development of autopilots and electronic navigation systems has greatly aided the crew in flying precise routes in all weather conditions while at the same time reducing pilot workload. Advances in high-integrity onboard computing and electronics technology have resulted in a significant increase in the capability of these subsystems to perform more reliably, efficiently, and safely. Onboard computing and control system capability has provided new design approaches for the aircraft designer. By using automatic control systems to stabilize the aircraft, the designer can relax certain conventional aerodynamic stability requirements and achieve aircraft performance benefits. Thus, modern fighter aircraft are designed with low levels, or in fact, negative levels of longitudinal static stability to boost maneuvering capability and cruise performance, relying on the use of full-time, full-authority automatic stability augmentation systems to stabilize the aircraft. During the next 20 years, GNC systems will become a driving force in aircraft design. Instead of making separately designed major aircraft systems work together, the designer will exploit the interaction and integration of aerodynamic, structural, and propulsion system controls to provide a better aircraft. The benefits of such integrated designs have been demonstrated already. Integrated digital control of the engine inlet and autopilot systems on a NASA YF-12 research aircraft resulted in a range increase of 7 percent. A civil transport derivative using extensions on each wing and an active control system to minimize the requirement for structural modifications achieved significant cruise performance improvements. These are first-generation applications of advanced GNC systems. More significant benefits are achievable by the year 2000. Complete integration of aerodynamic, propulsion and structural controls, and mission avionics will provide dramatically better aircraft performance, new capability (low observability, supermaneuverability) and/or improved mission effectiveness. This requires a concurrent, multidisciplinary design approach early in the design stage. The role of advanced GNC systems in future aircraft is not an option.

Fraser, Donald C.↗
NASA NTRS1980

YF-12 cooperative airframe/propulsion control system program, volume 1

Several YF-12C airplane analog control systems were converted to a digital system. Included were the air data computer, autopilot, inlet control system, and autothrottle systems. This conversion was performed to allow assessment of digital technology applications to supersonic cruise aircraft. The digital system was composed of a digital computer and specialized interface unit. A large scale mathematical simulation of the airplane was used for integration testing and software checkout.

Anderson, D. L.↗