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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 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
NASA NTRS2010

Space Technology 5 (ST-5) Observations of Field-Aligned Currents: Temporal Variability

Space Technology 5 (ST-5) is a three micro-satellite constellation deployed into a 300 x 4500 km, dawn-dusk, sun-synchronous polar orbit from March 22 to June 21, 2006, for technology validations. In this paper, we present a study of the temporal variability of field-aligned currents using multi-point magnetic field measurements from STS. The data demonstrate that masoscale current structures are commonly embedded within large-scale field-aligned current sheets. The meso-scale current structures are very dynamic with highly variable current density and/or polarity in time scales of about 10 min. They exhibit large temporal variations during both quiet and disturbed times in such time scales. On the other hand, the data also shown that the time scales for the currents to be relatively stable are about I min for meso-scale currents and about 10 min for large scale current sheets. These temporal features are obviously associated with dynamic variations of their particle carriers (mainly electrons) as they respond to the variations of the parallel electric field in auroral acceleration region. The characteristic time scales for the temporal variability of meso-scale field-aligned currents are found to be consistent with those of auroral parallel electric field.

Le, Guan↗
NASA NTRS2009

Trajectory Reconstruction of the ST-9 Sounding Rocket Experiment Using IMU and Landmark Data

This paper presents trajectory reconstruction of the ST-9 sounding rocket experiment using the onboard IMU data and descent imagery. The raw IMU accelerometer measurements are first converted into inertial acceleration and then used in trajectory integration. The descent images are pre-processed using a map-matching algorithm and unique landmarks for each image are created. Using the converted IMU data and descent images, the result from dead-reckoning and the kinematic-fix approaches are first compared with the GPS measurements. Then, both the IMU data and landmarks are processed together using a batch least-squares filter and the position, velocity, stochastic acceleration, and camera orientation of each image are estimated. The reconstructed trajectory is compared with the GPS data and the corresponding formal uncertainties are presented. The result shows that IMU data and descent images processed with a batch filter algorithm provide the trajectory accuracy required for pin-point landing.

Park, Ryan S.↗
DOE OSTI2024

Community Public Mobility Using On-Demand, Low-Speed Electric Vehicles: A Case Study in Downtown St. Louis, Missouri

Legacy fixed route transit systems designed to serve commuters struggle to provide efficient and effective service for short neighborhood trips and for population groups unable to access and egress transit stops using active modes (e.g., elderly, disabled). Neighborhood on-demand transit (ODT) services using low-speed electric vehicles (LSEV) are an innovative technological solution that can help fill this gap in service (e.g., short, high-frequency trips) for diverse populations and trip types. This study evaluated user characteristics and travel behavior for a neighborhood ODT service (using LSEVs) in downtown St. Louis, Missouri using responses from a community survey (n=244), ridership data, and vehicle trajectory information. A comparative analysis between neighborhood ODT, fixed route transit, and transportation network companies (TNC) was also conducted from the perspectives of total travel time, cost, and greenhouse gas emissions. Ultimately, the goal of the analysis was to motivate and inform holistic public mobility systems where different services are optimized to meet specific community needs. Findings indicate that the neighborhood ODT was effective at reaching diverse populations (elderly (20%), lower income (27%), and households with limited access to private vehicles (34%)). ODT reduced total travel time by 32% compared to fixed route transit, produced 2.4 - 4.3 times less greenhouse gas emissions per passenger mile (compared to transit and TNCs), and was more affordable (free to users) than alternative options ($1 for transit, $10-12 for TNCs). Overall satisfaction rates were high, with 80% of respondents rating the service a 4 or 5 out of 5.

ADVANCED PROPULSION SYSTEMS↗
NASA NTRS1999

Design of the ST 3 Formation Flying Interferometer

The interferometer will operate in both a single spacecraft mode and a formation flying mode using two spacecraft. The primary goal is to validate interferometer and formation flying technology for future missions.

ST 3 optical interferometry formation flying↗
NASA NTRS2005

Assessing Technology Maturity for ST-9 Technology Validation Experiments

This viewgraph presentation reviews the process of assessing the maturity of a technology for use in NASA missions. The NASA New Millennium Program (NMP) identifies and flight validates breakthrough technologi es that will significantly benefit future operational Space and Earth Science missions NMP conducts two types of flight validation projec ts for the Space Science Enterprise: (1) Integrated System Validatio n Projects, and (2) Stand-Alone Subsystem Validation Projects.

Space Technology (ST) 9↗
DOE OSTI2015

Energy Transition Initiative: Island Energy Snapshot - St. Lucia (Fact Sheet)

This profile provides a snapshot of the electricity generation or reduction technologies, including solar hot water heating, available to Saint Lucia, one of six Caribbean countries that make up the Windward Islands - the southern arc of the Lesser Antilles chain - at the eastern end of the Caribbean Sea. Heating and transportation fuels are not addressed.

14 SOLAR ENERGY↗
DOE OSTI2020

Energy Snapshot - St. Lucia

This profile provides a snapshot of the electricity capacity and generation profile of Saint Lucia, one of six Caribbean countries that make up the Windward Islands - the southern arc of the Lesser Antilles chain - at the eastern end of the Caribbean Sea.

44 EE - Strategic Programs, Energy Transition Init↗
DOE OSTI2018

Calculations of the relative energies of the low-lying electronic states of 2,7-naphthoquinodimethane and 2,7-naphthoquinone. Substitution of oxygen for CH 2 is predicted to increase the singlet-triplet energy difference ( ΔE ST )

CASSCF and CASPT2 calculations have been performed on the triplet and two lowest-lying singlet states of the 2,7-naphthoquinodimethane (NQDM) and 2,7-naphthoquinone (NQ) diradicals. Both diradicals are predicted to have triplet ground states but to differ in the ordering of the two lowest singlet states, with E(1A1) < E(1B2) in NQDM, but E(1A1) > E(1B2) in NQ. The reason for the difference in ordering of the singlet states in these two diradicals is discussed. The state reordering is shown to be responsible for the prediction that the substitution of the oxygens in NQ for the CH2 groups in NQDM increases, rather than decreases, the singlet-triplet energy separation (EST).

Hrovat, David A.↗