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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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26 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS2016

Comparison of Structural and Functional Ocular Outcomes Between 14- and 70 Day Bed Rest

Purpose: To compare structural and functional ocular outcomes in healthy human subjects undergoing 14- and/or 70-day head-down-tilt bed rest (HDTBR). We hypothesized the amount of HDTBR-induced ocular changes be affected by the HDTBR duration. Methods: The studies were conducted at the NASA Flight Analogs Research Unit, The University of Texas Medical Branch at Galveston, Galveston, TX. Participants were selected using NASA standard screening procedures. Standardized NASA screening procedures and bed rest conditions (e.g., strict sleep-wake cycle, standardized diet, continuous video monitoring) were implemented in both studies. Participants maintained a 6deg HDTBR position for 14 and/or 70 consecutive days and did not engage in exercise. Weekly ophthalmological examinations were conducted in the sitting (pre/post-bed rest only) and HDT positions. Ocular outcomes of interest included: near best-corrected visual acuity (BCVA); spherical equivalent, as determined by cycloplegic autorefraction; Goldmann applanation tonometry and iCare (Icare Finland Oy, Espoo, Finland) intraocular pressure (IOP) measurement; color vision; red dot test; modified Amsler grid test; confrontational visual field; stereoscopic color fundus photography; Spectralis OCT (Heidelberg Engineering, GmbH, Heidelberg, Germany) retinal nerve fiber layer thickness (RNFLT), peripapillary and macular retinal thicknesses. Mixed-effects linear models were used to compare pre- and post-HDTBR observations between 14- and 70-day HDTBR for our continuously scaled outcomes.

Cromwell, R. L.↗
NASA NTRS2017

Earth Science Project Office (ESPO) Field Experiences During ORACLES, ATom, KORUS and POSIDON

Very often, scientific field campaigns entail years of planning and incur substantial cost, especially if they involve the operation of large research aircraft in remote locations. Deploying and operating these aircrafts even for short periods of time poses challenges that, if not addressed properly, can have significant negative consequences and potentially jeopardize the success of a scientific campaign. Challenges vary from country to country and range from safety, health, and security risks to differences in cultural and social norms. Our presentation will focus on sharing experiences on the ESPO 2016 conducted field campaigns ORACLES, ATom, KORUS and POSIDON. We will focus on the best practices, lessons learned, international relations and coordination aspects of the country-specific experiences. This presentation will be part of the ICARE Conference (2nd International Conference on Airborne Research for the Environment (ICARE 2017) that will focus on "Developing the infrastructure to meet future scientific challenges". This unique conference and gathering of facility support experts will not only allow for dissemination and sharing of knowledge but also promote collaboration and networking among groups that support scientific research using airborne platforms around the globe.

Salazar, Vidal↗
NASA NTRSDate not supplied

Sirius: Simulation and Evaluation of Tactical Conflict Management in an Urban Environment

This presentation provides an overview of the SIRIUS framework, updates to the ICAROUS core modules, and highlights the results of recent simulation and evaluation of tactical deconfliction in an urban environment. The SIRIUS simulation framework provides a fast time method for simulation a large number of aircraft in parallel. Updates to the ICAROUS core modules highlighted in the presentation include the evaluation of the encounter type geometry and changes to the resolution type selection based on the encounter type and following right of way (ROW) rules. The main objective of the simulation was to evaluate the use of strategic and tactical conflict management strategies using a set of simulated UAM scenarios.

Andrew Peters↗
NASA NTRS2016

Influence of Exercise Modality on Cerebral-Ocular Hemodynamics and Pressures

Background: Moderate and high intensity aerobic or resistance exercise has clearly identified benefits for cardiac, muscle, and bone health. However, the impact of such exercise - either as a mitigating or an exacerbating factor - on the development of the visual impairment and intracranial pressure syndrome (VIIP) is unknown. Accordingly, our aim was to characterize the effect of an acute bout of resistance (RE), moderate-intensity continuous (CE), and high-intensity interval exercise (IE) during a cephalad fluid shift on cerebral-ocular hemodynamics and pressures. Methods: 10 male subjects (36 plus or minus 9 years) completed 4 testing days in a 15 degree head-down tilt (HDT): (1) assessment of maximum volume of O (sub 2), (2) RE session (4 sets of 12 repetition maximum leg press exercise), (3) CE session (30 minutes of cycling at 60 percent maximum volume of O (sub 2)), and (4) IE session (4 by 4-minute intervals of exercise at 85 percent maximum volume of O (sub 2) with 3-minute active rest periods). During each session, blood flow (Vivid-e, GE Healthcare) in extracranial arteries (common carotid artery, CCA; internal carotid artery, ICA; external carotid artery, ECA and vertebral artery, VA), and mean blood flow velocity in middle cerebral artery (MCA), internal jugular pressure (IJP; VeinPress), and intraocular pressure (IOP; Icare PRO) were measured at rest, at the end of each resistance or interval set, and every 5 minutes during continuous exercise. Translaminar pressure gradient (TLPG) was estimated by subtracting IJP from IOP. Results: There were no differences across days in pre-exercise resting blood flows or pressures. IOP decreased slightly from HDT rest (20.2 plus or minus 2.3 millimeters of mercury) to exercise (RE: 19.2 plus or minus 2.8 millimeters of mercury; CE: 18.9 plus or minus 3.2 millimeters of mercury; IE: 20.1 plus or minus 2.8 millimeters of mercury), while IJP decreased during CE (31.6 plus or minus 9.5 millimeters of mercury) and RE (32.0 plus or minus 8.1 millimeters of mercury), and increased during IE (35.1 plus or minus 9.5 millimeters of mercury) from HDT rest (33.3 plus or minus 6.5 millimeters of mercury). Estimated TLPG was increased during IE only. Compared to RE and CE, IE resulted in the greatest increase in MCA blood flow velocity and extracranial artery blood flow. Conclusions: These preliminary results suggest that high-intensity IE acutely increases cerebral blood flow, IJP, and TLPG. Alterations in TLPG is one mechanism that may contribute to optic nerve sheath edema in astronauts. Accordingly, acutely raising IOP and/or orbital pressure during exercise could optimize cerebral-ocular pressures during spaceflight.

Scott, J.↗
NASA NTRS2019

Overview of the PLEXIL Plan Execution Technology and its Applications in Autonomous Piloting Projects at NASA

Automated planning is a key Artificial Intelligence technology enabling Unmanned Aerial Systems (UAS) and the eminent reality of Urban Air Mobility (UAM). It produces plans, which formalize procedures often performed by humans. Plans differ from other kinds of computer programs in their ability to react and interact with a dynamically changing environment. Aviation plans must encode the procedural knowledge, reasoning capability, and capacity for multi-tasking held by competent human pilots. Correct execution of these plans (performed by software called an executive) in the dynamic airspace environment is vital to the success of each automated flight, and the safety of the vehicle and all things in its path. In the early 2000s NASA developed a plan representation language and executive called PLEXIL (Plan Execution Interchange Language) that has successfully been applied in several NASA aviation and UAS projects. Autonomy Operating System (AOS), Cockpit Hierarchical Automated Planning and Execution (CHAP-E), and ICAROUS are all projects that have used PLEXIL to help encode and automatically execute flight procedures, some normally performed by human pilots. AOS also automates a subset of pilot/Air Traffic Control communication towards enabling UAS entry into the National Airspace. PLEXIL has been open-source software since 2008 and has seen usage in a wide range of prototypical autonomy applications in academia, government, and industry. In this presentation, we describe PLEXIL and highlight its significant accomplishments in the aviation domain.

Dalal, Michael↗