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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Mooring Load Monitoring of a Wave Energy Converter Using a Self-Synchronizing Underwater Acoustic Network

A self-synchronizing underwater acoustic network, designed for remote monitoring of mooring loads in Wave Energy Converters (WEC), has been developed and tested. This network uses Time Division Multiple Access and operates self-contained with the ability for users to remotely transmit commands to the network as needed. Each node is a self-contained unit, consisting of a protocol adaptor board, an underwater acoustic modem and a battery pack. A node can be connected to a load cell, to a topside user or to the WEC. Every node is swapable. The protocol adaptor board, named Protocol Adaptor for Digital LOad Cell (PADLOC) supports a variety of digital load cell message formats (CAN, MODBUS, custom ASCII) and underwater acoustic modem serial formats. PADLOC enables topside users to connect to separate load cells through a user-specific command.

acoustic↗
NASA NTRS1975

Characterization of measurements in quantum communication

A characterization of quantum measurements by operator valued measures is presented. The generalized measurements include simultaneous approximate measurement of noncommuting observables. This characterization is suitable for solving problems in quantum communication. Two realizations of such measurements are discussed. The first is by adjoining an apparatus to the system under observation and performing a measurement corresponding to a self-adjoint operator in the tensor-product Hilbert space of the system and apparatus spaces. The second realization is by performing, on the system alone, sequential measurements that correspond to self-adjoint operators, basing the choice of each measurement on the outcomes of previous measurements. Simultaneous generalized measurements are found to be equivalent to a single finer grain generalized measurement, and hence it is sufficient to consider the set of single measurements. An alternative characterization of generalized measurement is proposed. It is shown to be equivalent to the characterization by operator-values measures, but it is potentially more suitable for the treatment of estimation problems. Finally, a study of the interaction between the information-carrying system and a measurement apparatus provides clues for the physical realizations of abstractly characterized quantum measurements.

Chan, V. W. S.↗
NASA NTRS1976

Analytical Work in Support of the Design and Operation of Two Dimensional Self Streamlining Test Sections

A method has been developed for accurately computing the imaginary flow fields outside a flexible walled test section, applicable to lifting and non-lifting models. The tolerances in the setting of the flexible walls introduce only small levels of aerodynamic interference at the model. While it is not possible to apply corrections for the interference effects, they may be reduced by improving the setting accuracy of the portions of wall immediately above and below the model. Interference effects of the truncation of the length of the streamlined portion of a test section are brought to an acceptably small level by the use of a suitably long test section with the model placed centrally.

Judd, M.↗
NASA NTRS1984

The design and operational development of self-streamlining 2-dimensional flexible walled test sections

Self streamlining two dimensional flexible walled test sections eliminate the uncertainties found in data from conventional test sections particularly at transonic speeds. The test section sidewalls are rigid, while the floor and ceiling are flexible and are positioned to streamline shapes by a system of jacks, without reference to the model. The walls are therefore self streamlining. Data are taken from the model when the walls are good streamlines such that the inevitable residual wall induced interference is acceptably small and correctable. Successful two dimensional validation testing at low speeds has led to the development of a new transonic flexible walled test section. Tunnel setting times are minimized by the development of a rapid wall setting strategy coupled with on line computer control of wall shapes using motorized jacks. Two dimensional validation testing using symmetric and cambered aerofoils in the Mach number range up to about 0.85 where the walls are just supercritical, shows good agreement with reference data using small height-chord ratios between 1.5 and unity.

Wolf, S. W. D.↗
NASA NTRS2010

Human in the Loop Simulation Measures of Pilot Response Delay in a Self-Separation Concept of Operations

A human-in-the-loop (HITL) simulation experiment was conducted by the National Aeronautics and Space Administration (NASA) to assess airline transport pilots performance and reported acceptance of the use of procedures relying on airborne separation assistance and trajectory management tools. This study was part of a larger effort involving two NASA centers that includes multiple HITL experiments planned over the next few years to evaluate the use of automated separation assurance (SA) tools by both air traffic controllers and pilots. This paper presents results of measured pilot response delay that subject pilots incurred when interacting with cockpit tools for SA and discusses possible implications for future concept and procedures design.

Consiglio, Maria C.↗
NASA NTRS1972

Eigenvalues of singular differential operators by finite difference methods. I.

Approximation of the eigenvalues of certain self-adjoint operators defined by a formal differential operator in a Hilbert space. In general, two problems are studied. The first is the problem of defining a suitable Hilbert space operator that has eigenvalues. The second problem concerns the finite difference operators to be used.

Baxley, J. V.↗
NASA NTRS1972

Eigenvalues of singular differential operators by finite difference methods. II.

Note is made of an earlier paper which defined finite difference operators for the Hilbert space L2(m), and gave the eigenvalues for these operators. The present work examines eigenvalues for higher order singular differential operators by using finite difference methods. The two self-adjoint operators investigated are defined by a particular value in the same Hilbert space, L2(m), and are strictly positive with compact inverses. A class of finite difference operators is considered, with the idea of application to the theory of Toeplitz matrices. The approximating operators consist of a good approximation plus a perturbing operator.

Baxley, J. V.↗
DOE OSTI2021

Jet Fuel Production at the Pittsburgh Airport: GTL via Fischer-Tropsch Synthesis

The Pittsburgh International Airport (PIT)—with the Allegheny County Airport Authority (which manages PIT)—has established itself as a leader in resiliency by becoming the first major United States (U.S.) airport to have a self-sustaining microgrid, providing electricity, heating, and cooling for airport operations. The microgrid is powered by natural gas and solar power produced on the airport property and was completed in Summer 2021. This study examines the feasibility of producing jet fuel at the airport to provide a secure supply of aviation fuel, furthering PIT’s ability to weather supply disruptions and operate self-sufficiently. Gas-to-liquids (GTL) is a commercially available technology that converts natural gas to liquid hydrocarbons, including synthetic jet fuel. A GTL facility at PIT could convert natural gas from onsite wells to jet fuel, effectively doubling the onsite fuel stores in the event of a supply disruption. Moreover, GTL provides a pathway to renewable jet fuel production and reduced greenhouse gas (GHG) emissions from the aviation sector, particularly if renewable natural gas (RNG) is used as a feedstock or other renewable energy sources are used for energy inputs. This study has found that it would be technically feasible to construct and operate a GTL facility on PIT’s property. The approximately 6,000-barrel per day (BPD) facility evaluated would produce nearly 70 million (MM) gallons (gal) of synthetic jet fuel per year, which could supplant nearly all (85 percent) current jet fuel consumption at PIT. Given the current blend limitation of 50 percent Fischer-Tropsch fuels by volume, the plant would have excess production capacity available for the United States Air Force (USAF) Pittsburgh Air Reserve Station and the USAF 171st Air Refueling Wing co-located at the airport.

03 NATURAL GAS↗
NASA NTRS2003

Methods for Determining the Level of Autonomy to Design into a Human Spaceflight Vehicle: A Function Specific Approach

The next-generation human spaceflight vehicle is in a unique position to realize the benefits of more than thirty years of technological advancements since the Space Shuttle was designed. Computer enhancements, the emergence of highly reliable decision-making algorithms, and an emphasis on efficiency make an increased use of autonomous systems highly likely. NASA is in a position to take advantage of these advances and apply them to the human spaceflight environment. One of the key paradigm shifts will be the shift, where appropriate, of monitoring, option development, decision-making, and execution responsibility from humans to an Autonomous Flight Management (AFM) system. As an effort to reduce risk for development of an AFM system, NASA engineers are developing a prototype to prove the utility of previously untested autonomy concepts. This prototype, called SMART (Spacecraft Mission Assessment and Replanning Tool), is a functionally decomposed flight management system with an appropriate level of autonomy for each of its functions. As the development of SMART began, the most important and most often asked question was, How autonomous should an AFM system be? A thorough study of the literature through 2002 surrounding autonomous systems has not yielded a standard method for designing a level of autonomy into either a crewed vehicle or an uncrewed vehicle. The current focus in the literature on defining autonomy is centered on developing IQ tests for built systems. The literature that was analyzed assumes that the goal of all systems is to strive for complete autonomy from human intervention, rather than identifying how autonomous each function within the system should have been. In contrast, the SMART team developed a method for determining the appropriate level of autonomy to be designed into each function within a system. This paper summarizes the development of the Level of Autonomy Assessment Tool and its application to the SMART project.

AFM (AUTONOMOUS FLIGHT MANAGEMENT)↗
NASA NTRS2010

Ultra Low Temperature Ultra Low Power Instrument Packages for Planetary Surfaces

Achievement of solar system exploration roadmap goals will involve robotic or human deployment and longterm operation of surface science packages remote from human presence, thus requiring autonomous, self-powered operation. The major challenge such packages face will be operating during long periods of darkness in extreme cold potentially without the Pu238 based power and thermal systems available to Apollo era packages (ALSEP). Development of such science payloads will thus require considerable optimization of instrument and subsystem design, packaging and integration for a variety of planetary surface environments in order to support solar system exploration fully. Our work supports this process through the incorporation of low temperature operational components and design strategies which radically minimize power, mass, and cost while maximizing the performance under extreme surface conditions that are in many cases more demanding than those routinely experienced by spacecraft in deep space. Chief instruments/instrument package candidates include those which could provide long-term monitoring of the surface and subsurface environments for fundamental science and human crew safety. The initial attempt to design a 10 instrument environmental monitoring package with a solar/battery based power system led to a package with a unacceptably large mass (500 kg) of which over half was battery mass. In phase 1, a factor of 5 reduction in mass was achieved, first through the introduction of high performance electronics capable of operating at far lower temperature and then through the use of innovative thermal balance strategies involving the use of multi-layer thin materials and gravity-assisted heat pipes. In phase 2, reported here, involves strategies such as universal incorporation of ULT/ULP digital and analog electronics, and distributed or non-conventionally packaged power systems. These strategies will be required to meet the far more challenging thermal requirements of operating through a normal 28 day diurnal cycle. The limited temperature range of efficient battery operation remains the largest obstacle.

Clark, P. E.↗
NASA NTRS2006

A Bearingless Switched-Reluctance Motor for High Specific Power Applications

A 12-8 switched-reluctance motor (SRM) is studied in bearingless (or self-levitated) operation with coil currents limited to the linear region to avoid magnetic saturation. The required motoring and levitating currents are summed and go into a single motor coil per pole to obtain the highest power output of the motor by having more space for motor coil winding. Two controllers are investigated for the bearingless SRM operation. First, a model-based controller using the radial force, which is adjusted by a factor derived from finite element analysis, is presented. Then a simple and practical observation-based controller using a PD (proportional-derivative) control algorithm is presented. Both controllers were experimentally demonstrated to 6500 rpm. This paper reports the initial efforts toward eventual self levitation of a SRM operating into strong magnetic core saturation at liquid nitrogen temperature.

Choi, Benjamin B.↗
DOE OSTI2021

A Self-Synchronizing Underwater Acoustic Network for Mooring Load Monitoring of a Wave Energy Converter

This paper reports on the development of a self-synchronizing underwater acoustic network developed for remote monitoring of mooring loads in Wave Energy Converters (WECs). This network uses Time Division Multiple Access and operates self-contained with the ability for users to remotely transmit commands to the network as needed. Each node is a self-contained unit, consisting of a protocol adaptor board, an FAU-DPAM underwater acoustic modem and a battery pack. A node can be connected to a load cell, to a topside user or to the WEC. Every node is swapable. The protocol adaptor board, named Protocol Adaptor for Digital LOad Cell (PADLOC) supports a variety of digital load cell message formats (CAN, MODBUS, custom ASCII) and underwater acoustic modem serial formats. PADLOC enables topside users to connect to separate load cells through a user-specific command. This is especially important if the user is monitoring multiple load cells during deployment or maintenance, when the primary data system may be offline. Each PADLOC board handles formatting, buffering and has a one-on-one serial connection with each pair (node) of a digital load cell and acoustic modem. In addition, each PADLOC board handles the timekeeping and power saving features for each node. The only limitation is the data bit rate and delay limitations associated with the underwater acoustic modem. A four node self-synchronizing network has been developed to demonstrate the load cell monitoring capability using the PADLOC technology on the CalWave WEC.

acoustic↗
NASA NTRS1993

Observables, measurements and phase operators from a Bohmian perspective

Bohmian mechanics is a deterministic theory of point particles in motion. While avoiding all the paradoxes of nonrelativistic quantum mechanics, it yields the quantum formalism itself--especially the role of self-adjoint operators--as a macroscopic measurement formalism. As an 'application' it is shown that much of the confusion connected with the phase operator for the electromagnetic field arises from a misunderstanding of the role of operators in quantum theory.

Daumer, Martin↗
NASA NTRS2012

Autonomous Operations Planner: A Flexible Platform for Research in Flight-Deck Support for Airborne Self-Separation

The Autonomous Operations Planner (AOP), developed by NASA, is a flexible and powerful prototype of a flight-deck automation system to support self-separation of aircraft. The AOP incorporates a variety of algorithms to detect and resolve conflicts between the trajectories of its own aircraft and traffic aircraft while meeting route constraints such as required times of arrival and avoiding airspace hazards such as convective weather and restricted airspace. This integrated suite of algorithms provides flight crew support for strategic and tactical conflict resolutions and conflict-free trajectory planning while en route. The AOP has supported an extensive set of experiments covering various conditions and variations on the self-separation concept, yielding insight into the system s design and resolving various challenges encountered in the exploration of the concept. The design of the AOP will enable it to continue to evolve and support experimentation as the self-separation concept is refined.

Karr, David A.↗
NASA NTRS2013

Influence of Tailored Applied Magnetic Fields on High-Power MPD Thruster Current Transport and Onset-Related Phenomena

This work investigated the effects of tailored, externally-applied magnetic fields on current transport and near-anode processes in the plasma discharge of a magnetoplasmadynamic thruster (MPDT). Electrical and plasma diagnostics were used to investigate how localized applied magnetic fields could mitigate the effects of the "onset" phenomena, including large-amplitude terminal voltage fluctuations and high anode fall voltages associated with unstable operation and anode erosion. An MPDT with a multi-channel hollow cathode was developed and tested with quasi-steady pulses of 1 millisecond duration at power levels of 36 kilowatts (20 volts, 1800 amperes) to 3.3 milliwatts (255 volts, 13.1 kiloamperes) with argon propellant in three different magnetic configurations: self-field, applied B field tangential to the anode lip near the exit plane, and applied cusp B field. The current pattern and current densities redistributed to follow the applied poloidal magnetic field lines, which created increased conduction paths to the anode. Also, the anode fall voltage was substantially reduced with both applied B field topologies over a large range of currents. For example, at 10.7 kiloamperes, the cusp applied magnetic field decreased anode fall voltages from 45-83 volts down to 15 volts or lower along much of the anode. The amplitude and frequency of the voltage fluctuations were also reduced over a broad range of currents with the applied fields. E.g., the standard deviations of the fluctuations were lowered by 37-49 percent at 8-9 kiloamperes. In addition, decreases in the mean terminal voltages as large as 31 percent were measured with the applied magnetic fields. These effects are shown to be associated with the increased current conduction along the applied magnetic field lines in the near-anode region. These results also suggest a reduction in frequency and intensity of current-concentrating filaments and anode spots, which contribute to erosion. Overall, both applied magnetic field configurations enabled significant reductions in onset-related behaviors relative to self-field operation. These improvements should lead to reduced anode erosion, i.e., improved thruster lifetime, and increased thruster efficiency with the applied fields. The applied fields used in this study differ from both the topologies and relative field strengths typically used in the vast majority of conventional, so-called "applied-field MPD thrusters" (AF-MPDTs). These results suggest a distinctive and more effective approach to influencing the near-anode phenomena and mitigating the deleterious effects of onset with appropriately designed applied magnetic fields.

delta-V↗
NASA NTRS1978

Self-scanned photodiode array - High performance operation in high dispersion astronomical spectrophotometry

A multichannel spectrophotometric detector system has been developed using a 1024 element self-scanned silicon photodiode array, which is now in routine operation with the high-dispersion coude spectrograph of the University of Texas McDonald Observatory 2.7-m telescope. Operational considerations in the use of such arrays for high precision and low light level spectrophotometry are discussed. A detailed description of the system is presented. Performance of the detector as measured in the laboratory and on astronomical program objects is described, and it is shown that these arrays are highly effective detectors for high dispersion astronomical spectroscopy.

Vogt, S. S.↗