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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 649 records · Page 36
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

The Jefferson Lab Eta Factory (JEF) experiment

The Jefferson Lab Eta Factory (JEF) experiment is an upcoming experiment designed to run in Hall D at Jefferson Lab using an upgraded GlueX spectrometer to study various decays of the ? meson. The GlueX spectrometer consists of a ?2 Tesla solenoid magnet housing a liquid hydrogen target and drift chambers used for tracking charged particles and an array of lead glass blocks (the Forward Calorimeter (FCAL)) downstream of the magnet for detecting neutral particles. The decays of the ? meson can be used to measure the light quark mass ratio via the ???+???0 channel and allow access to higher-order terms in Chiral Perturbation Theory via the ???0?? channel. The decays can also be used to constrain new charge-conjugation violating/parity conserving (CVPC) reactions and to search for signatures of dark matter. In particular, the ???0?? channel can be used to search for lepto-phobic dark vector (B) bosons in the reaction ??B? (B??0?) or dark scalar (S) bosons in the reaction ???0S (S???). Studying the rare radiative decay channel ???0?? requires replacing the 4×4×45 cm3 lead glass blocks in the inner region of the FCAL with 2×2×20 cm3 lead tungstate crystals, which will provide twice better position and energy resolution. This talk will describe the JEF physics program and the upgrade to the FCAL.

Taylor, Simon↗
DOE OSTI2017

A global map of saltmarshes

Saltmarshes are extremely valuable but often overlooked ecosystems, contributing to livelihoods locally and globally through the associated ecosystem services they provide, including fish production, carbon storage and coastal protection. Despite their importance, knowledge of the current spatial distribution (occurrence and extent) of saltmarshes is incomplete. In light of increasing anthropogenic and environmental pressures on coastal ecosystems, global data on the occurrence and extent of saltmarshes are needed to draw attention to these critical ecosystems and to the benefits they generate for people. Such data can support resource management, strengthen decision-making and facilitate tracking of progress towards global conservation targets set by multilateral environmental agreements, such as the Aichi Biodiversity Targets of the United Nations' (UN's) Strategic Plan for Biodiversity 2011-2020, the Sustainable Development Goals of the UN's 2030 Agenda for Sustainable Development and the Ramsar Convention.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1973

Orbit determination by range-only data.

The determination of satellite orbits for use in geodesy using range-only data has been examined. A recently developed recursive algorithm for rectification of the nominal orbit after processing each observation has been tested. It is shown that when a synchronous satellite is tracked simultaneously with a subsynchronous geodetic target satellite, the orbits of each may be readily determined by processing the range information. Random data errors and satellite perturbations are included in the examples presented.

Duong, N.↗
NASA NTRS1975

The Mariner Jupiter/Uranus 1979 mission

Some results of recent planning studies for a Mariner Jupiter/Uranus 1979 (MJU 79) mission are discussed. It is noted that a 1979 launch will provide unique approach geometries to Uranus because, when viewed from an approaching spacecraft in 1985, the pole-on orientation of the planet and its satellite orbit tracks will seem to describe a target, permitting a long observational period of almost all the lighted hemispheres of Uranus and its five known satellites. The overall scientific objectives for a MJU 79 mission are outlined, and mission considerations are discussed, including energy requirements, use of a Jupiter gravity-assist to reduce flight-time and launch vehicle-capability requirements, and various dual-launch strategies. Basic trajectories for Jupiter and Uranus encounters are considered, and general characteristics of the MJU 79 spacecraft are described. Expected scientific returns from a typical Uranus encounter is examined, including high-resolution scanning of the planet and its satellites, more accurate estimates of satellite radii and masses, and high-resolution IR studies of the planet.

Hyde, J. R.↗
NASA NTRS1979

Shoe-box orbit determination system for SMM preliminary results

The implementation of both sequential and batch methods of estimation on IMP-16 microprocessors was investigated. Simulated data was used from a tracking and data relay satellite whose target satellite was the Solar Maximum Mission. An interesting feature of the hardware was the use of two interconnected IMP-16's. Some preliminary results from the study, as well as the difficulties and advantages in the use of microprocessors, are presented.

Tasaki, K. K.↗
NASA NTRS1979

Shuttle orbiter radar cross-sectional analysis

Theoretical and model simulation studies on signal to noise levels and shuttle radar cross section are described. Pre-mission system calibrations, system configuration, and postmission system calibration of the tracking radars are described. Conversion of target range, azimuth, and elevation into radar centered east north vertical position coordinates are evaluated. The location of the impinging rf energy with respect to the target vehicles body axis triad is calculated. Cross section correlation between the two radars is presented.

Cooper, D. W.↗
NASA NTRS1984

Quaternions for Galileo scan platform control

The application of quaternions for the articulation control of the Galileo scan platform is presented in this paper. The purpose of selecting quaternions is to minimize onboard computation time and program size. Attention has been focused on performing inertial pointing while the spacecraft is in a dual spin configuration. Target quaternion and relative target quaternion are introduced and used to specify the target position of the scan platform for point-to-point absolute slews and mosaic relative slews, respectively. The pointing error of the platform is represented by an error quaternion which is converted into gimbal angular errors defining the attitude change. For path control, a moving target quaternion is generated; the corresponding tracking error quaternion and the related spacecraft motion compensation capability are also addressed. A sample slew case is used to demonstrate the implementation of these concepts.

Breckenridge, W. G.↗
NASA NTRS1986

Shuttle communication and tracking systems signal design and interface compatibility analysis

Various options for the Dedicated Payload Communication Link (DPCL) were evaluated. Specific subjects addressed include: payload to DPCL power transfer in the proximity of the payload, DPCL antenna pointing considerations, and DPCL transceiver implementations which can be mounted on the deployed antenna boom. Additional analysis of the Space Telescope performance was conducted. The feasibility of using the Global Positioning System (GPS) for attitude determination and control for large spacecraft was examined. The objective of the Shuttle Orbiter Radar Test and Evaluation (SORTE) program was to quantify the Ku-band radar tracking accuracy using White Sands Missile Range (WSMR) radar and optical tracking equipment, with helicopter and balloon targets.

Source record↗
NASA NTRS1989

Modeling and sensory feedback control for space manipulators

The positioning control problem of the endtip of space manipulators whose base are uncontrolled is examined. In such a case, the conventional control method for industrial robots based on a local feedback at each joint is not applicable, because a solution of the joint displacements that satisfies a given position and orientation of the endtip is not decided uniquely. A sensory feedback control scheme for space manipulators based on an artificial potential defined in a task-oriented coordinates is proposed. Using this scheme, the controller can easily determine the input torque of each joint from the data of an external sensor such as a visual device. Since the external sensor is mounted on the unfixed base, the manipulator must track the moving image of the target in sensor coordinates. Moreover the dynamics of the base and the manipulator are interactive. However, the endtip is proven to asymptotically approach the stationary target in an inertial coordinate frame by the Liapunov's method. Finally results of computer simulation for a 6-link space manipulator model show the effectiveness of the proposed scheme.

Masutani, Yasuhiro↗
NASA NTRS1991

Experimental validation of docking and capture using space robotics testbeds

This presentation describes the application of robotic and computer vision systems to validate docking and capture operations for space cargo transfer vehicles. Three applications are discussed: (1) air bearing systems in two dimensions that yield high quality free-flying, flexible, and contact dynamics; (2) validation of docking mechanisms with misalignment and target dynamics; and (3) computer vision technology for target location and real-time tracking. All the testbeds are supported by a network of engineering workstations for dynamic and controls analyses. Dynamic simulation of multibody rigid and elastic systems are performed with the TREETOPS code. MATRIXx/System-Build and PRO-MATLAB/Simulab are the tools for control design and analysis using classical and modern techniques such as H-infinity and LQG/LTR. SANDY is a general design tool to optimize numerically a multivariable robust compensator with a user-defined structure. Mathematica and Macsyma are used to derive symbolically dynamic and kinematic equations.

Spofford, John↗
NASA NTRS1993

Topographic slope from the SAR interferometric phase gradient

A new algorithm for the direct calculation of topographic slope maps from synthetic aperture radar (SAR) interferograms is presented. The algorithm derives slope maps without first requiring the creation of a digital elevational model (DEM) from the interferogram, thus obviating the need for high SNR in the interferogram and altitude calibration points for the scene. SAR data useful for interferometry has been collected by the Active Microwave Imager on board the ERS-1 satellite, when it was in a short period repeat orbit. Two passes of the radar sensor form a cross-track interferometric baseline. For a point target at some position (x,y,h), the interferometric phase difference phi is proportional to the difference in path lengths for the two sensor positions to the scatterer. Given the phase difference as measured in the complex interferogram and an accurate baseline geometry, the position of the scatterer, most significantly the height h, can be determined through triangulation. The interferometric phase measurement however is known only modulo 2-pi, and hence it is necessary to determine the correct multiple of 2-pi to add to the phase at each point to obtain an estimate of the actual phase with respect to an absolute datum. This phase unwrapping process is required for creating DEM's, and is difficult or impossible for regions of low SNR or SAR image layover. The new algorithm described here derives slope maps without requiring phase unwrapping.

Werner, Charles L.↗
NASA NTRS1994

The AEDC aerospace chamber 7V: An advanced test capability for infrared surveillance and seeker sensors

An advanced sensor test capability is now operational at the Air Force Arnold Engineering Development Center (AEDC) for calibration and performance characterization of infrared sensors. This facility, known as the 7V, is part of a broad range of test capabilities under development at AEDC to provide complete ground test support to the sensor community for large-aperture surveillance sensors and kinetic kill interceptors. The 7V is a state-of-the-art cryo/vacuum facility providing calibration and mission simulation against space backgrounds. Key features of the facility include high-fidelity scene simulation with precision track accuracy and in-situ target monitoring, diffraction limited optical system, NIST traceable broadband and spectral radiometric calibration, outstanding jitter control, environmental systems for 20 K, high-vacuum, low-background simulation, and an advanced data acquisition system.

Simpson, W. R.↗
NASA NTRS2000

Adaptation of the phase of the human linear vestibulo-ocular reflex (LVOR) and effects on the oculomotor neural integrator

The phase of the translational linear VOR (LVOR) can be adaptively modified by exposure to a visual-vestibular mismatch. We extend here our earlier work on LVOR phase adaptation, and discuss the role of the oculomotor neural integrator. Ten subjects were oscillated laterally at 0.5 Hz, 0.3 g peak acceleration, while sitting upright on a linear sled. LVOR was assessed before and after adaptation with subjects tracking the remembered location of a target at 1 m in the dark. Phase and gain were measured by fitting sine waves to the desaccaded eye movements, and comparing sled and eye position. To adapt LVOR phase, the subject viewed a computer-generated stereoscopic visual display, at a virtual distance of 1 m, that moved so as to require either a phase lead or a phase lag of 53 deg. Adaptation lasted 20 min, during which subjects were oscillated at 0.5 Hz/0.3 g. Four of five subjects produced an adaptive change in the lag condition (range 4-45 deg), and each of five produced a change in the lead condition (range 19-56 deg), as requested. Changes in drift on eccentric gaze suggest that the oculomotor velocity-to-position integrator may be involved in the phase changes.

Non-NASA Center↗
DOE OSTI2018

Analysis Insights: The Key Role Analysis Plays in R&D

Over the last two decades, the National Renewable Energy Laboratory (NREL) has been applying its analytical expertise to help guide and advance renewable energy technology research and development (R&D). Working shoulder-to-shoulder with world-class researchers - at NREL, other national laboratories, and universities - and industry partners, NREL analysts continue to search for answers to emerging energy challenges every day. Our objective methodologies and tools are now helping stakeholders assess and prioritize R&D efforts as fast as new innovative technologies transition from concept to commercial application. Throughout that journey, NREL's analyses highlight key technical barriers, compare tradeoffs among proposed technology development pathways, track progress toward performance and cost targets, and illuminate the impacts of proposed innovations. This edition of NREL's Analysis Insights takes a deeper look at the role analysis has played in guiding renewable energy innovation at our laboratory, and beyond. In doing so, the report substantiates what we have known for 20 years - that informed analyses must remain at the leading edge of future R&D efforts.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2015

Multileaf Collimator Tracking Improves Dose Delivery for Prostate Cancer Radiation Therapy: Results of the First Clinical Trial

Purpose: To test the hypothesis that multileaf collimator (MLC) tracking improves the consistency between the planned and delivered dose compared with the dose without MLC tracking, in the setting of a prostate cancer volumetric modulated arc therapy trial. Methods and Materials: Multileaf collimator tracking was implemented for 15 patients in a prostate cancer radiation therapy trial; in total, 513 treatment fractions were delivered. During each treatment fraction, the prostate trajectory and treatment MLC positions were collected. These data were used as input for dose reconstruction (multiple isocenter shift method) to calculate the treated dose (with MLC tracking) and the dose that would have been delivered had MLC tracking not been applied (without MLC tracking). The percentage difference from planned for target and normal tissue dose-volume points were calculated. The hypothesis was tested for each dose-volume value via analysis of variance using the F test. Results: Of the 513 fractions delivered, 475 (93%) were suitable for analysis. The mean difference and standard deviation between the planned and treated MLC tracking doses and the planned and without-MLC tracking doses for all 475 fractions were, respectively, PTV D{sub 99%} −0.8% ± 1.1% versus −2.1% ± 2.7%; CTV D{sub 99%} −0.6% ± 0.8% versus −0.6% ± 1.1%; rectum V{sub 65%} 1.6% ± 7.9% versus −1.2% ± 18%; and bladder V{sub 65%} 0.5% ± 4.4% versus −0.0% ± 9.2% (P<.001 for all dose-volume results). Conclusion: This study shows that MLC tracking improves the consistency between the planned and delivered doses compared with the modeled doses without MLC tracking. The implications of this finding are potentially improved patient outcomes, as well as more reliable dose-volume data for radiobiological parameter determination.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
NASA NTRS2021

Covid-19 Impact Monitoring for Climate Environment (Greenhouse Gases)

To track atmospheric CO2 changes resulting from the lockdowns, observations collected by the NASA Orbiting Carbon Observatory-2 (OCO-2) satellite and Japan’s Greenhouse gases Observing SATellite (GOSAT) in 2020 were compared to results collected in previous years. The OCO-2 results were used to search for changes on regional scales over the globe. Targeted observations from GOSAT were used to track changes in large urban areas, such as Beijing and Tokyo. Both types of observations yielded key insights into the CO2 changes accompanying the economic disruptions caused by the COVID-19 lockdowns. ESA, NASA and JAXA developed the dashboard jointly to monitor the climate impacts of COVID-19.

greenhouse gases↗