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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 1,171 records · Page 65

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DOE OSTI2020

Interplanetary Protons versus Interacting Protons in the 2017 September 10 Solar Eruptive Event

We analyze the relativistic proton emission from the Sun during the eruptive event on 2017 September 10, which caused a ground-level enhancement (GLE 72) registered by the worldwide network of neutron monitors. Using the neutron monitor data and interplanetary transport modeling both along and across interplanetary magnetic field (IMF) lines, we deduce parameters of the proton injection into the interplanetary medium. The inferred injection profile of the interplanetary protons is compared with the profile of the >100 MeV γ -ray emission observed by the Fermi Large Area Telescope, attributed to pion production from the interaction of >300 MeV protons at the Sun. GLE 72 started with a prompt component that arrived along the IMF lines. This was followed by a more prolonged enhancement caused by protons arriving at the Earth across the IMF lines from the southwest. The interplanetary proton event is modeled using two sources—one source at the root of the Earth-connected IMF line and another source situated near the solar western limb. The maximum phase of the second injection of interplanetary protons coincides with the maximum phase of the prolonged >100 MeV γ -ray emission that originated from a small area at the solar western limb, below the current sheet trailing the associated coronal mass ejection (CME). A possible common source of interacting protons and interplanetary protons is discussed in terms of proton acceleration at the CME bow shock versus coronal (re-)acceleration in the wake of the CME.

79 ASTRONOMY AND ASTROPHYSICS↗

NASA NTRS1976

Single phase inverter for a three phase power generation and distribution system

A breadboard design of a single-phase inverter with sinusoidal output voltage for a three-phase power generation and distribution system was developed. The three-phase system consists of three single-phase inverters, whose output voltages are connected in a delta configuration. Upon failure of one inverter the two remaining inverters will continue to deliver three-phase power. Parallel redundancy as offered by two three-phase inverters is substituted by one three-phase inverter assembly with high savings in volume, weight, components count and complexity, and a considerable increase in reliability. The following requirements must be met: (1) Each single-phase, current-fed inverter must be capable of being synchronized to a three-phase reference system such that its output voltage remains phaselocked to its respective reference voltage. (2) Each single-phase, current-fed inverter must be capable of accepting leading and lagging power factors over a range from -0.7 through 1 to +0.7.

Lindena, S. J.↗

NASA NTRS1982

Effects of nuclear forces on ion thermalization in high-temperature plasmas

A number of investigations have been concerned with the kinetic theory and processes associated with a relativistic electron gas. Gould (1981) has considered a condition in which upon the ultimate thermalization the temperature can be such that the electron gas is highly relativistic while the gas of protons and other ions is nonrelativistic. With the nuclear component nonrelativistic but having energies in the MeV range and above, it is necessary to consider the effects of nuclear forces in the scattering of the ions in their thermalization. The effects of nuclear forces in the thermalization of ions in plasmas have been computed, principally in connection with problems of controlle; fusion. The present investigation is concerned with an attempt to express results in analytic form to as great a degree as possible. The p-p problem, which is the fundamental problem in astrophysical plasma, is studied. Attention is given to a low-energy formulation, the s-wave phase shift, the effective stopping number, Fokker-Planck operators, and the interaction with the electron gas.

Gould, R. J.↗

NASA NTRS1985

IUE results on the AM Herculis stars CW 1103, E1114, and PG 1550

IUE data are presented on three AM Her stars (CW 1103 + 254, E1114 + 182, and PG 1550 + 191) which are used in conjunction with optical and IR fluxes to study the accretion characteristics of these systems in relation to other polars.The time-resolved IUE spectra of CW 1103 show that the column contributes little to the UV, while the white dwarf, with a temperature of approximately 13,000 K and a distance of approximately 140 pc, is the dominant source of light. Thus, CW 1103 at its normal state is basically very similar to VV Pup at its low accretion state, except for increased IR emission that is not connected to the accretion column or the secondary. E1114 also appears to be a low UV emitter, but better data are needed to constrain the observed temperature. On the other hand, PG 1550 has a steeper UV distribution, with a possibility for a hot Rayleigh-Jeans component at wavelengths less than 1600 A. This source is very similar to E1405-451 and AM Her itself.

Szkody, P.↗

NASA NTRS1988

The GISS global climate-middle atmosphere model. II - Model variability due to interactions between planetary waves, the mean circulation and gravity wave drag

The variability which arises in the GISS Global Climate-Middle Atmosphere Model on two time scales is reviewed: interannual standard deviations, derived from the five-year control run, and intraseasonal variability as exemplified by statospheric warnings. The model's extratropical variability for both mean fields and eddy statistics appears reasonable when compared with observations, while the tropical wind variability near the stratopause may be excessive possibly, due to inertial oscillations. Both wave 1 and wave 2 warmings develop, with connections to tropospheric forcing. Variability on both time scales results from a complex set of interactions among planetary waves, the mean circulation, and gravity wave drag. Specific examples of these interactions are presented, which imply that variability in gravity wave forcing and drag may be an important component of the variability of the middle atmosphere.

Rind, D.↗

NASA NTRS1991

Optical observations of active galactic nuclei

The most important observed characteristics are described of active galactic nuclei, concentrating on their optical spectra. Connections with the standard model of such objects are emphasized. Some of the new observational developments that are leading to modifications of the standard model are outlined; these include spatial variations of the ionization parameters in the broad line region, the possible existence of a very dense component in the broad line region, and the presence of an intermediate density zone between the broad line and narrow line regions. Evidence for hidden Seyfert 1 nuclei and anisotropic ionizing radiation is also reviewed. The search for, and properties of, intrinsically weak Seyfert 1 nuclei are summarized, with emphasis given to the very low luminosity object in the late type dwarf galaxy NGC 4395. A discussion is also presented of the possibility that low level activity in some galactic nuclei might actually be produced by bursts of star formation and their associated supernovae.

Filippenko, Alexei V.↗

NASA NTRS1992

The MHD structure of the plasmasheet boundary. I - Tangential momentum balance and consistency with slow mode shocks

The MHD structure of the plasmasheet boundary in the near tail is investigated on the basis of data from the AMPTE/IRM spacecraft. The relationship between the change in the tangential velocity predicted by the Rankine-Hugoniot relations for a discontinuity with a normal magnetic field and the measured change in the tangential velocity for about 80 crossings is presented. The measured change is almost always much less than the predicted value. It is suggested that either there is not usually a normal component of the magnetic field across the boundary (combined with previous work on pressure balance, this implies that the boundary is a tangential discontinuity), or the boundary is not usually well-modeled as a planar, time-stationary MHD discontinuity. It is proposed that the magnetic connection to the earth inhibits the formation of slow mode shocks.

Cattell, C. A.↗

NASA NTRS1994

MUADEE: Mars Upper Atmosphere Dynamics, Energetics, and Evolution discovery mission. Executive summary volume

This document is the final report of the MAUDEE (Mars Upper Atmosphere Dynamics, Energetics, and Evolution) consortium. It describes a low cost Discovery mission to investigate the upper atmosphere of Mars and to understand the manner in which Mars has evolved over geologic time. In keeping with the innovative philosophy permeating the Discovery Program and in order to minimize the burden of reading an extensive prose exposition, a new presentation format has been adopted. The format involves a series of view graphs with facing text. The view graphs form the basis of a complete oral presentation of the MAUDEE mission and the facing text provides more detailed, but still brief, explanatory descriptions. Readers can scan the view graphs and/or read the facing text at their discretion. The oral presentation of this study was given to code SL personnel at NASA Headquarters on February 23, 1994. MAUDEE is an essential component of the Mars Exploration Program. It provides the information required to understand the evolution of the planet via the escape of volatiles. It provides the key measurements needed to understand the upper atmosphere of the last of the three terrestrial planets to be so studied. It connects and supplements investigations based on other Mars missions: Mars Surveyor, Planet-B and Mars-96. The MAUDEE mission plan involves a combination of remote and in-situ sensors, housed in three instrument packages. The sensors make measurements of the atmospheric regions between 60-200 km. These instruments are based on extensive heritage from Earth explorers and Pioneer Venus. The mission scenario has several phases and employs aerobraking maneuvers to lower initial apoapsis, thereby reducing fuel requirements. The spacecraft has body-mounted solar cells, enabling deep diving into the Martian atmosphere. The orbital inclination allows for pole-to-pole latitudinal sweeps in an initial elliptical phase, followed by a circular phase affording detailed diurnal measurements. The nominal mission duration at Mars is one Mars year.

Killeen, Timothy L.↗

NASA NTRS1992

Electrical capacitance clearanceometer

A hot gas turbine engine capacitive probe clearanceometer is employed to measure the clearance gap or distance between blade tips on a rotor wheel and its confining casing under operating conditions. A braze sealed tip of the probe carries a capacitor electrode which is electrically connected to an electrical inductor within the probe which is inserted into a turbine casing to position its electrode at the inner surface of the casing. Electrical power is supplied through a voltage controlled variable frequency oscillator having a tuned circuit in which the probe is a component. The oscillator signal is modulated by a change in electrical capacitance between the probe electrode and a passing blade tip surface while an automatic feedback correction circuit corrects oscillator signal drift. A change in distance between a blade tip and the probe electrode is a change in capacitance therebetween which frequency modulates the oscillator signal. The modulated oscillator signal which is then processed through a phase detector and related circuitry to provide an electrical signal is proportional to the clearance gap.

Hester, Norbert J.↗

NASA NTRS1999

Method and apparatus for cold gas reinjection in through-flow and reverse-flow wave rotors

A method and apparatus for cold gas reinjection in through-flow and reverse-flow wave rotors having a plurality of channels formed around a periphery thereof. A first port injects a supply of cool air into the channels. A second port allows the supply of cool air to exit the channels and flow to a combustor. A third port injects a supply of hot gas from the combustor into the channels. A fourth port allows the supply of hot gas to exit the channels and flow to a turbine. A diverting port and a reinjection port are connected to the second and third ports, respectively. The diverting port diverts a portion of the cool air exiting through the second port as reinjection air. The diverting port is fluidly connected to the reinjection port which reinjects the reinjection air back into the channels. The reinjection air evacuates the channels of the hot gas resident therein and cools the channel walls, a pair of end walls of the rotor, ducts communicating with the rotor and subsequent downstream components. In a second embodiment, the second port receives all of the cool air exiting the channels and the diverting port diverts a portion of the cool air just prior to the cool air flowing to the combustor.

Nalim, M. Razi↗

NASA NTRS2013

Space Images for NASA JPL Android Version

This software addresses the demand for easily accessible NASA JPL images and videos by providing a user friendly and simple graphical user interface that can be run via the Android platform from any location where Internet connection is available. This app is complementary to the iPhone version of the application. A backend infrastructure stores, tracks, and retrieves space images from the JPL Photojournal and Institutional Communications Web server, and catalogs the information into a streamlined rating infrastructure. This system consists of four distinguishing components: image repository, database, server-side logic, and Android mobile application. The image repository contains images from various JPL flight projects. The database stores the image information as well as the user rating. The server-side logic retrieves the image information from the database and categorizes each image for display. The Android mobile application is an interfacing delivery system that retrieves the image information from the server for each Android mobile device user. Also created is a reporting and tracking system for charting and monitoring usage. Unlike other Android mobile image applications, this system uses the latest emerging technologies to produce image listings based directly on user input. This allows for countless combinations of images returned. The backend infrastructure uses industry-standard coding and database methods, enabling future software improvement and technology updates. The flexibility of the system design framework permits multiple levels of display possibilities and provides integration capabilities. Unique features of the software include image/video retrieval from a selected set of categories, image Web links that can be shared among e-mail users, sharing to Facebook/Twitter, marking as user's favorites, and image metadata searchable for instant results.

Nelson, Jon D.↗

NASA NTRSDate not supplied

Hybrid-Electric Aero-Propulsion Controls Testbed Results

NASA is supporting the development of Electrified Aircraft Propulsion (EAP) technology due to its potential to reduce aircraft fuel burn, emissions, and noise as well as improving safety and performance. One focus of this research is the electrification of conventional turbomachinery propulsion systems, which offers ways to improve the performance and operability of turbine-engine powered aircraft through the addition of electro-mechanical systems. These hybrid-electric turbine engines provide additional actuation and energy management control opportunities for improving stability and transient response behavior. This paper summarizes the results of a Hardware-in-the-Loop (HIL) test performed at the NASA Electric Aircraft Testbed (NEAT) during the summer of 2022. The test demonstrates the feasibility and performance of an advanced energy management control strategy by integrating a simulated turbofan engine with scaled electro-mechanical hardware. A full-scale real-time reference model of a geared turbofan was run alongside a scaled electro-mechanical system representing the electrified turbofan components operating at a megawatt-scale power level. The model was interfaced with the hardware through a novel closed-loop control and scaling algorithm that emulated the dynamic speed and torque response of the turbofan shafts. The control strategy was implemented on the electrical machines connected to the emulated turbomachinery shafts. The results from the testbed are compared against simulations that predict the testbed and geared turbofan model operation. The energy management control strategy successfully changed the operating point of the engine model and improved its stability during throttle transients. These results also demonstrate the success of the novel closed loop control and scaling approach for emulating turbomachinery and elevate the Technology Readiness Level (TRL) of the energy management control strategy.

Aeronautics↗

NASA NTRSDate not supplied

Sub-Seasonal Variability of the Asian Summer Monsoon Transport of CO and Aerosols to the UTLS and Implications for Global Atmospheric Composition

The upper troposphere/ lower stratosphere (UTLS) is a climate sensitive region. The Asian summer monsoon (ASM) is a major component in the climate system. It transports aerosols and trace gases from the most polluted regions in Asia to UTLS where they spread out to the global atmosphere. Although ASM is a seasonal phenomenon with strongest global influences usually seen in summer, it is highly dynamic and connected to other weather and climate systems, with significant spatial and temporal variability ranging from sub-seasonal weather scale to multi-year climate scale. The interplay of multi-scale dynamics inevitably determines the variability of the transport pathways and atmospheric composition in the UTLS.

sub-seasonal variability↗

NASA NTRS2023

Hybrid-Electric Aero-Propulsion Controls Testbed Results

Aeronautics↗

DOE OSTI2021

Improving Real-world Measurement-based Phase Identification in Power Distribution Feeders with a Novel Reliability Criteria Assessment

This paper is concerned with solving the phase identification problem in a real-world smart grid project; where there is only a few smart meters available on each of the five power distribution feeders in the test site in Riverside, CA. The main idea is to develop and use two reliability criteria that can identify the most reliable components in a broken-down phase identification analysis; thereby significantly improving the accuracy of phase identification. The proposed method consists of three steps. The results from field implementation reveal the accuracy and consistency of the proposed method in practice, in correctly and reliability identifying the phase connectivity.

Phase identification Data-driven method Sliding wi↗

DOE OSTI2022

A multi-modal scanning system to digitize CBRNE emergency response scenes

A handheld system developed to digitize a contextual understanding of the scene at a chemical, biological, radiological, nuclear and/or explosives (CBRNE) events is described. The system uses LiDAR and cameras to create a colorized 3D model of the environment, which helps domain experts that are supporting responders in the field. To generate the digitized model, a responder scans any suspicious objects and the surroundings by carrying the system through the scene. The scanning system provides a real-time user interface to inform the user about scanning progress and to indicate any areas that may have been missed either by the LiDAR sensors or the cameras. Currently, the collected data are post-processed on a different device, building a colorized triangular mesh of the encountered scene, with the intention of moving this pipeline to the scanner at a later point. The mesh is sufficiently compressed to be sent over a reduced bandwidth connection to a remote analyst. Furthermore, the system tracks fiducial markers attached to diagnostic equipment that is placed around the suspicious object. The resulting tracking information can be transmitted to remote analysts to further facilitate their supporting efforts. The paper will discuss the system's design, software components, the user interface used for scanning a scene, the necessary procedures for calibration of the sensors, and the processing steps of the resulting data. The discussion will close by evaluating the system's performance on 11 scenes.

Prins, Nicholas↗

DOE OSTI2025

Infrastructure-Based Cooperative Perception at a Traffic Intersection: Overview and Challenges

Traffic intersections are crucial and challenging nodes in transportation networks where multiple lanes of vehicles and pedestrians converge. About one-quarter of traffic fatalities and about one-half of all traffic injuries in the United States happen at traffic intersections . Effective management of these intersections is important to ensure safety and efficiency of all users - vehicles, pedestrians, cyclists, and vulnerable road users (VRUs). With advancements in sensor perception technologies such as radar, light detection and ranging (lidar), and cameras, traffic intersections are developing into dynamic and data-rich environments. By using these data to create a real-time digital twin, we can enable real-time data-driven decision making and a range of applications such as sharing perception information to connected vehicles (CVs) and connected autonomous vehicles (CAVs), safety affirmative signaling, and curb optimizing to improve efficiency and enhance safety.This paper presents an overview of the concept and examines the challenges involved in implementing an infrastructure-based cooperative perception engine at a traffic intersection. In addition to outlining the physical components, this study also addresses important challenges involved in a multi-sensor system. We present results from deploying the National Renewable Energy Laboratory's (NREL's) Infrastructure Perception and Control (IPC) mobile trailer at a traffic intersection in the city of Colorado Springs, Colorado, USA that employed multiple radars and lidars to capture the data. This study provides necessary practical learning for the Cooperative Driving Automation (CDA) and traffic engineering communities for next-generation infrastructure-based cooperative perception that promises improvements in signal control for optimized traffic flow, among other applications, and documents findings for ongoing research and development efforts in other areas.

ADVANCED PROPULSION SYSTEMS,MATHEMATICS AND COMPUT↗

NASA NTRS1991

A guide to NASA's Pilot Land Data System (PLDS)

NASA's Pilot Land Data System (PLDS) is a distributed information management system designed to support NASA's land science community. The PLDS provides a wide range of services including management of information about scientific data, access to a library of scientific data, a data ordering capability, communications, connection to data analysis facilities, and electronic mail. The PLDS provides these services by offering the scientist the capability to search for and order data, and to communicate electronically with other scientists and computers. Three functions enable scientists to find what data are available and where they reside. The first two, Find data summaries and Read detailed descriptions give summary and detailed descriptions about data sets or groups of related data sets, science, projects, and institutions which archive land data. The third, gives information about specific pieces of data. This last function has two components, Search systemwide inventory and Search local inventory. The first component enables the user to find data elements (images, geological samples, transects, maps, etc.) that exist anywhere in the PLDS while the second has only information about data at the local site. The first enables the user to find pieces of data from several different data sets with the same temporal and spatial coverage and other elements common to most data sets, while the second allows the user to select a data set based on these descriptors and on those that are unique to a data set. The PLDS provides capabilities that enable electronic file transfers, intercomputer connection, and electronic mail. Both TCP/IP and DECnet protocols are supported via the NASA Science Internet (NIS). Access is also available through Telenet.

Source record↗