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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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All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

Anodized aluminum coatings for thermal control. II - Environmental effects and cracking

The environmental effects of thermal cycling and humidity on coating cracking are examined. Experimental measurements of thermal deflection were used to calculate values for the thermal expansion coefficient and the in situ elastic modulus of an anodized aluminum. The thermal expansion coefficient is found to be approximately the same as for alumina in bulk form. The modulus in atmospheres with less than 100 ppm water is about 12,500 ksi. Two sets of experiments are used to study cracking directly during thermal excursions: one determines the minimum temperature (Tc) at which cracks first appear during a single heating cycle and the other involves rapid thermal cycling (RTC) between fixed T max and T min values. Fatigue models for describing initiation of the first crack and the development of multiple cracking are presented, which can be used as the basis for prediction of LEO cracking.

Mcclung, R. C.↗
NASA NTRS1992

Efficiency of an AMTEC recirculating test cell, experiments and projections

The alkali metal thermal to electric converter (AMTEC) is an electrochemical device for the direct conversion of heat to electrical energy with efficiencies potentially near Carnot. The future usefulness of AMTEC for space power conversion depends on the efficiency of the devices. Systems studies have projected from 15 to 35 percent thermal to electric conversion efficiencies, and one experiment has demonstrated 19 percent efficiency for a short period of time. Recent experiments in a recirculating test cell (RTC) have demonstrated sustained conversion efficiencies as high as 10.2 percent early in cell life and 9.7 percent after maturity. Extensive thermal and electrochemical analysis of the cell during several experiments demonstrated that the efficiency could be improved in two ways. First, the electrode performance could be improved. The electrode for these tests operated at about one third the power density of state of the art electrodes. The low power density was caused by a combination of high series resistance and high mass flow resistance. Reducing these resistances could improve the efficiency to greater than 10 percent. Second, the cell thermal performance could be improved. Efficiencies greater than 14 percent could be realized through reducing the radiative thermal loss. Further improvements to the efficiency range predicted by systems studies can be accomplished through the development and use of an advanced condenser with improved reflectivity, close to that of a smooth sodium film, and the series connecting of individual cells to further reduce thermal losses.

Underwood, M. L.↗
NASA NTRS1993

RighTime: A real time clock correcting program for MS-DOS-based computer systems

A computer program is described which effectively eliminates the misgivings of the DOS system clock in PC/AT-class computers. RighTime is a small, sophisticated memory-resident program that automatically corrects both the DOS system clock and the hardware 'CMOS' real time clock (RTC) in real time. RighTime learns what corrections are required without operator interaction beyond the occasional accurate time set. Both warm (power on) and cool (power off) errors are corrected, usually yielding better than one part per million accuracy in the typical desktop computer with no additional hardware, and RighTime increases the system clock resolution from approximately 0.0549 second to 0.01 second. Program tools are also available which allow visualization of RighTime's actions, verification of its performance, display of its history log, and which provide data for graphing of the system clock behavior. The program has found application in a wide variety of industries, including astronomy, satellite tracking, communications, broadcasting, transportation, public utilities, manufacturing, medicine, and the military.

Becker, G. Thomas↗
NASA NTRS2000

Highly Parallel Computing Architectures by using Arrays of Quantum-dot Cellular Automata (QCA): Opportunities, Challenges, and Recent Results

There has been significant improvement in the performance of VLSI devices, in terms of size, power consumption, and speed, in recent years and this trend may also continue for some near future. However, it is a well known fact that there are major obstacles, i.e., physical limitation of feature size reduction and ever increasing cost of foundry, that would prevent the long term continuation of this trend. This has motivated the exploration of some fundamentally new technologies that are not dependent on the conventional feature size approach. Such technologies are expected to enable scaling to continue to the ultimate level, i.e., molecular and atomistic size. Quantum computing, quantum dot-based computing, DNA based computing, biologically inspired computing, etc., are examples of such new technologies. In particular, quantum-dots based computing by using Quantum-dot Cellular Automata (QCA) has recently been intensely investigated as a promising new technology capable of offering significant improvement over conventional VLSI in terms of reduction of feature size (and hence increase in integration level), reduction of power consumption, and increase of switching speed. Quantum dot-based computing and memory in general and QCA specifically, are intriguing to NASA due to their high packing density (10(exp 11) - 10(exp 12) per square cm ) and low power consumption (no transfer of current) and potentially higher radiation tolerant. Under Revolutionary Computing Technology (RTC) Program at the NASA/JPL Center for Integrated Space Microelectronics (CISM), we have been investigating the potential applications of QCA for the space program. To this end, exploiting the intrinsic features of QCA, we have designed novel QCA-based circuits for co-planner (i.e., single layer) and compact implementation of a class of data permutation matrices, a class of interconnection networks, and a bit-serial processor. Building upon these circuits, we have developed novel algorithms and QCA-based architectures for highly parallel and systolic computation of signal/image processing applications, such as FFT and Wavelet and Wlash-Hadamard Transforms.

Fijany, Amir↗
NASA NTRS2017

Efficient Trajectory Options Allocation for the Collaborative Trajectory Options Program

The Collaborative Trajectory Options Program (CTOP) is a Traffic Management Initiative (TMI) intended to control the air traffic flow rates at multiple specified Flow Constrained Areas (FCAs), where demand exceeds capacity. CTOP allows flight operators to submit the desired Trajectory Options Set (TOS) for each affected flight with associated Relative Trajectory Cost (RTC) for each option. CTOP then creates a feasible schedule that complies with capacity constraints by assigning affected flights with routes and departure delays in such a way as to minimize the total cost while maintaining equity across flight operators. The current version of CTOP implements a Ration-by-Schedule (RBS) scheme, which assigns the best available options to flights based on a First-Scheduled-First-Served heuristic. In the present study, an alternative flight scheduling approach is developed based on linear optimization. Results suggest that such an approach can significantly reduce flight delays, in the deterministic case, while maintaining equity as defined using a Max-Min fairness scheme.

Traffic Management Initiative (TMI)↗
NASA NTRS2017

Efficient Trajectory Options Allocation for the Collaborative Trajectory Options Program

The Collaborative Trajectory Options Program (CTOP) is a Traffic Management Initiative (TMI) intended to control the air traffic flow rates at multiple specified Flow Constrained Areas (FCAs), where demand exceeds capacity. CTOP allows flight operators to submit the desired Trajectory Options Set (TOS) for each affected flight with associated Relative Trajectory Cost (RTC) for each option. CTOP then creates a feasible schedule that complies with capacity constraints by assigning affected flights with routes and departure delays in such a way as to minimize the total cost while maintaining equity across flight operators. The current version of CTOP implements a Ration-by-Schedule (RBS) scheme, which assigns the best available options to flights based on a First-Scheduled-First-Served heuristic. In the present study, an alternative flight scheduling approach is developed based on linear optimization. Results suggest that such an approach can significantly reduce flight delays, in the deterministic case, while maintaining equity as defined using a Max-Min fairness scheme.

Rodionova, O.↗
NASA NTRS2018

Tactical Surface Metering Procedures for Charlotte Douglas International Airport

NASA has been collaborating with the Federal Aviation Administration (FAA) and aviation industry partners to develop and demonstrate new concepts and technologies for the Integrated Arrival, Departure, and Surface (IADS) traffic management capabilities under the Airspace Technology Demonstration 2 (ATD-2) project. The primary goal of the ATD-2 project is to improve the predictability and the operational efficiency of the air traffic system in metroplex environments while maintaining or improving throughput by enhancing and integrating arrival, departure and surface prediction, scheduling, and management systems. In the Phase 1 Baseline IADS Demonstration, the tactical surface scheduling capability and the user interfaces for ramp controllers and ramp traffic managers were implemented for ramp operations. The purpose of the tactical surface scheduling capability is to provide the airline ramp controller with aircraft pushback advisories that prevent surface congestion and to respond to surface and airspace constraints that become known over relatively short time horizons. For this purpose, the tactical surface metering tool first estimates the capacity of current and near-future runway resources from flight schedule and surveillance data. With demand forecasts and predicted taxi trajectories, this tool computes an efficient runway schedule of aircraft in the planning horizon based on their readiness, Earliest Off-Block Times (EOBTs), and a ration by schedule (RBS) rule. Details on the implementation of the Tactical Surface Metering tool will be provided in the full paper. Both pushback and recommended hold times advisories provided by this surface metering tool are shown on the user interfaces for the ramp controller and the ramp traffic manager, called Ramp Traffic Console (RTC) and Ramp Manager Traffic Console (RMTC), respectively. There is excess queue time in the system due to demand capacity imbalance, this time can be taken as a hold on the runway queue or at the gate and was referred to as the Metering Value. This metering value can be adjusted by the Ramp Manager in collaboration with Air Traffic Controller-Tower Traffic Management Coordinator (TMC). They selected a set of metering values as default values for the tool during human-in-the-loop simulation. As the metering value increases, there is a decrease in the gate hold and increase in the queue time at the runway. Procedures and Information needs related to managing the surface metering procedures were researched in the simulated environment. These procedures will be compared to the procedures adopted at Charlotte Douglas International Airport when the tools were deployed and adopted in November 2017 for one departure push bank per day. Feedback regarding initial issues, information needs such as the need to see EOBTs on the flight data tags and how they compare to scheduled times will also be discussed in the full paper. Initial results will be provided regarding the choice of the metering value and how it was adjusted on a daily basis and what procedures evolved will also be presented in the paper.

surface metering↗
NASA NTRS2019

Automatic Execution of Collision Avoidance and Return to Course Analysis (D.6.20) Experiment Review

This presentation details the experimental design for an upcoming engineering analysis of a mock version of the Airborne Collision Avoidance System (ACAS), specifically the 'Xu' variant, which is designed for unmanned aircraft platforms. As a component of the Unmanned Aircraft System (UAS) Integration into the National Airspace System (NAS) project, this engineering analysis intends to study aspects of ACAS Xu in two parts. In the first phase of the study, the display and alerting guidance for collision avoidance (CA) resolution advisories (RA) shown to pilots at a ground control station will be manipulated, varying in level of RA transparency and presentation of safe maneuver parameters. The second phase of the engineering analysis will examine pilots' response to increasing levels of automation in the tasks of collision avoidance and return-to-course (RTC).

Sadler, Garrett↗
NASA NTRS2002

SIM testbed 3 real-time control software

SIM System Testbed 3 (STB3) features three optical interferometers sharing a common baseline, as a dynamic representation of the SIM instrument. An artificial star feeding the interferometers is installed on a separate optics bench. All three interferometers use photons captured by avalanche photo diodes (APDs) to measure the position and quality of fringes, and additional pointing precision is achieved by fast steering mirrors (FSMs) that keep the star images centered on the beam combining optics using a CCD camera. Each interferometer uses internal metrology to measure changes in its optical pathlength. External metrology beams measure changes in the baseline vector. This system acquires and tracks white light fringes with one interferometer, while the other two acquire and track laser light fringes representing the bright guide stars that will be used by SIM. The white light source represents a dim star that cannot supply enough photons for the Science interferometer to lock onto fringes in closed-loop mode; instead it operates open-loop, using pathlength corrections fed to it from the two guide interferometers and the external metrology subsystem to reject disturbances and maintain the fringes. This tracking mode is known as Pathlength Feed Forward (PFF). The precise real-time behavior required to achieve this result is implemented by a complex set of interacting software control loops. This paper describes how these loops take advantage of the benefits of the RTC Core architecture, and how they work together to accomplish STB3's objectives.

interferometry↗
NASA NTRSDate not supplied

Modeling Relative Trajectory Costs for Airborne Trajectory Reroutes using Trajectory Option Sets

As part of the Increasing Diverse Operations Project (IDO), the Trajectory Options Program (TOS), which was introduced with the Collaborative Trajectory Options Program, is used in a novel way to help reroute airborne aircraft. Different trajectories in this TOS are ranked by a Relative Trajectory Cost (RTC) which had to be adapted from its original use expressing ground delay, into expressing costs in a dollar value to adapt to aircraft being airborne. For this, a set of models consisting of the parameters Fuel, Crew, Airspace and Downstream Congestion cost, has been developed in an attempt to represent linear and non-linear behavior of airline delay costs. While Fuel and Airspace Cost in this model increase linearly, the Parameter Crew consists of three subset factors which leverage an underlying Crew-Placement algorithm using the IDO scenario to model non-linearity. The parameter Downstream Congestion attempts to predict delay in minutes by looking at sector overload for each sector a selected trajectory passes through.

automation↗
NASA NTRSDate not supplied

ACAS Xr Part Task Sim, Preliminary Experiment Design

In early 2022, the Human Autonomy Teaming Lab (NASA Ames Research Center) will conduct a manned, human-in-the-loop (HITL) simulation. This part task HITL will begin the lab’s Hazard Perception and Avoidance (HPA) technical work under NASA’s Advanced Air Mobility (AAM), Automated Flight and Contingency Management (AFCM) Sub-Project. The goals will be to assess levels of automation for manned, electric vertical takeoff and landing (eVTOL) aircraft. This simulation will test manual and automated Resolution Advisory (RA) responses and return-to-course (RTC) maneuvers for the first version of the Airborne Collision Avoidance System’s (ACAS) rotary-wing (Xr) variant. This will be conducted on a fixed-based simulator designed to fly eVTOL aircraft while maneuvering for intruding traffic. Variables for this study include levels of autonomy (i.e., manual and automated) as well as the types of alerts at the onset of conflicts (i.e., Corrective and RA). The data collected will include response times, losses of well clear, and maneuver sizes and durations as well as subjective ratings like acceptability, perceived workload, and meaningful human control. Additional details and future anticipations are also discussed.

air taxis↗
NASA NTRSDate not supplied

Upgrading the 14x22 Data Acquisition System (DAS)

The 14-by 22-Foot Subsonic Tunnel recently completed development and installation of a new Data Acquisition System for use in the tunnel and in the Rotor Test Cell (RTC). Planning and development of this new system has been ongoing for several years, and installation was performed over this past year. This effort also required an upgrade of the facility infrastructure to support the upgraded power and cooling requirements. This presentation summarizes the new data acquisition system, improved capabilities, challenges of installation, and proposed future enhancements to the system.

wind tunnel↗
NASA NTRSDate not supplied

Hazard Perception & Avoidance (HPA): Part Task 1 - Results Outbrief

n April 2022, the Human Autonomy Teaming Lab (NASA Ames Research Center) conducted a manned, human-in-the-loop (HITL) simulation. This part task HITL began the lab’s Hazard Perception and Avoidance (HPA) technical work under NASA’s Advanced Air Mobility (AAM), Automated Flight and Contingency Management (AFCM) Sub-Project. The goals were to assess levels of automation for manned, electric vertical takeoff and landing (eVTOL) aircraft. This simulation tested manual and automated Resolution Advisory (RA) responses and return-to-course (RTC) maneuvers for the first version of the Airborne Collision Avoidance System’s (ACAS) rotary-wing (Xr) variant. This was conducted on a fixed-based simulator designed to fly eVTOL aircraft while maneuvering for intruding traffic. Variables for this study included levels of autonomy (i.e., manual and automated) as well as the types of alerts at the onset of conflicts (i.e., Corrective and RA). The data collected included response times, losses of well clear, and maneuver sizes and durations as well as subjective ratings like acceptability, and perceived workload. Additional details and future anticipations are also discussed.

air taxis↗
NASA NTRSDate not supplied

Hazard Perception & Avoidance (HPA), Assured Vehicle Automation 1 Simulation (AVA-1h) Results Outbrief

In late 2022, the Human Autonomy Teaming Lab (NASA Ames Research Center) conducted a manned, human-in-the-loop (HITL) simulation. This HITL was the lab’s second Hazard Perception and Avoidance (HPA) technical work under NASA’s Advanced Air Mobility (AAM), Automated Flight and Contingency Management (AFCM) Sub-Project. The goals were to assess detect and avoid technology for manned, electric vertical takeoff and landing (eVTOL) aircraft. This simulation tested Resolution Advisory (RA) responses and return-to-course (RTC) maneuvers for the second version of the Airborne Collision Avoidance System’s (ACAS) rotary-wing (Xr) variant. This was conducted at the center's Vertical Motion Simulator (VMS), on a motion-based platform, and was configured to fly eVTOL aircraft while maneuvering for intruding traffic. Variables for this study included ACAS Xr modes (i.e., TA/RA and DAA) and phases of flight (i.e., Cruise, Hover, and Approach). The data collected included response times, losses of well clear, and pilots' noncompliances to alerts and guidance as well as subjective ratings like acceptability and perceived workload. Additional details and future anticipations are also discussed.

ACAS Xr↗
NASA NTRSDate not supplied

Flood Detection with Synthetic Aperture Radar: A Case Study of Houston, Texas Following Hurricane Harvey (2017) using C- and X-Band Observations

Hurricane Harvey produced record-breaking rainfall of up to 60 inches resulting in extensive flooding in Houston, Texas, in late August and early September of 2017. The slow forward motion of the storm following landfall left much of the area unobservable to optical remote sensing instruments for several days due to cloud cover. The active nature of Synthetic Aperture Radar (SAR) instruments allows for observations through clouds, which can supplement efforts to estimate hurricane-induced flood impacts. A growing fleet of SAR constellations has helped lower the latency of imagery following a hurricane, allowing for more timely detections of flooding to help support emergency response efforts. In this study, we leverage publicly available C-band SAR observations from the European Space Agency’s Sentinel-1B (S1B) satellite, collected on 30 August, and X-band SAR imagery collected on 1 September by the Airbus TanDEM-X (TDX) satellite made available through the NASA Commercial Smallsat Data Acquisition (CSDA) program. For each dataset, one co-polarized, StripMap, Radiometric Terrain Corrected (RTC) image was used to create a binary water/no water classification map by referencing permanent water in the Cropland Data Layer (CDL) dataset to determine thresholds. A validation dataset of randomly distributed “ground truth” points was generated using optical imagery from PlanetScope on 31 August, where the domain had relatively little cloud cover. We found that the S1B- and TDX-derived open water maps achieved overall accuracies of 94.17% and 91.57%, respectively. The variation in performance is attributed to both the penetrative abilities of C- and X-band SAR wavelengths in vegetated areas and the increased spatial resolution of the commercial SAR (~3 m) over Sentinel-1 (30 m). While publicly available Sentinel-1 observations are commonly relied upon in response and recovery efforts, these results suggest that including commercial X-band SAR imagery could be beneficial by providing both increased spatial resolution and more frequent revisits when deriving post-event flood mapping products.

Alexander M Melancon↗