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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 523 records · Page 29
All sourcesNASA NTRSDOE OSTI
NASA NTRS2000

Combined dietary and exercise intervention for control of serum cholesterol in the workplace

PURPOSE: To elucidate a potential combined dietary and exercise intervention affect on cardiovascular risk reduction of the National Aeronautics and Space Administration Headquarters employees. DESIGN: A nonexperimental, longitudinal, clinical-chart review study (1987 to 1996) of an identified intervention group and a reference (not a control) group. SETTING: The study group worked in an office environment and participated in the annual medical examinations. SUBJECTS: An intervention group of 858 people with initially elevated serum cholesterol, and a reference group of 963 people randomly sampled from 10% of the study group. MEASURES: Serum cholesterol data were obtained for both groups, respectively, from pre- and postintervention and annual examinations. The reference group was adjusted by statistical exclusion of potential intervention participants. Regression equations (cholesterol vs. study years) for the unadjusted/adjusted reference groups were tested for statistical significance. INTERVENTION: An 8-week individualized, combined dietary and exercise program was instituted with annual follow-ups and was repeated where warranted. RESULTS: Only the unadjusted (but not the adjusted) reference group with initial mean total serum cholesterol levels above 200 mg/dL shows a significant 9-year decline trend and significant beta coefficient tests. An intervention effect is suggested. Mean high density lipoprotein cholesterol rose slightly in the intervention group but was maintained in the reference group. CONCLUSION: With potential design limitations, the NASA intervention program focusing on a high risk group may be associated to some degree, if not fully, with an overall cardiovascular risk profile improvement.

Occupational Health Services↗
NASA NTRS2005

Orbiter LH2 Feedline Flowliner Cracking Problem

In May of 2002, three cracks were found in the downstream flowliner at the gimbal joint in the LH2 feedline at the interface with the Low Pressure Fuel Turbopump (LPFP) of Space Shuttle Main Engine (SSME) #1 of Orbiter OV-104. Subsequent inspections of the feedline flowliners in the other orbiters revealed the existence of 8 additional cracks. No cracks were found in the LO2 feedline flowliners. A solution to the cracking problem was developed and implemented on all orbiters. The solution included weld repair of all detectable cracks and the polishing of all slot edges to remove manufacturing discrepancies that could initiate new cracks. Using the results of a fracture mechanics analysis with a scatter factor of 4 on the predicted fatigue life, the orbiters were cleared for return to flight with a one-flight rationale requiring inspections after each flight. OV-104 flew mission STS-112 and OV-105 flew mission STS-113. The post-flight inspections did not find any cracks in the repaired flowliners. At the request of the Orbiter Program, the NESC conducted an assessment of the Orbiter LH2 Feedline Flowliner cracking problem with a team of subject matter experts from throughout NASA.

Harris, Charles E.↗
NASA NTRS2006

Simulated Data for High Temperature Composite Design

The paper describes an effective formal method that can be used to simulate design properties for composites that is inclusive of all the effects that influence those properties. This effective simulation method is integrated computer codes that include composite micromechanics, composite macromechanics, laminate theory, structural analysis, and multi-factor interaction model. Demonstration of the method includes sample examples for static, thermal, and fracture reliability for a unidirectional metal matrix composite as well as rupture strength and fatigue strength for a high temperature super alloy. Typical results obtained for a unidirectional composite show that the thermal properties are more sensitive to internal local damage, the longitudinal properties degrade slowly with temperature, the transverse and shear properties degrade rapidly with temperature as do rupture strength and fatigue strength for super alloys.

Chamis, Christos C.↗
NASA NTRS2006

A Bioinformatics Facility for NASA

Building on an existing prototype, we have fielded a facility with bioinformatics technologies that will help NASA meet its unique requirements for biological research. This facility consists of a cluster of computers capable of performing computationally intensive tasks, software tools, databases and knowledge management systems. Novel computational technologies for analyzing and integrating new biological data and already existing knowledge have been developed. With continued development and support, the facility will fulfill strategic NASA s bioinformatics needs in astrobiology and space exploration. . As a demonstration of these capabilities, we will present a detailed analysis of how spaceflight factors impact gene expression in the liver and kidney for mice flown aboard shuttle flight STS-108. We have found that many genes involved in signal transduction, cell cycle, and development respond to changes in microgravity, but that most metabolic pathways appear unchanged.

Schweighofer, Karl↗
NASA NTRS2007

Life Support System Technologies for NASA Exploration Missions

The Lunar Mars Life Support Test series successfully demonstrated integration and operation of advanced technologies for closed-loop life support systems, including physicochemical and biological subsystems. Increased closure was obtained when targeted technologies, such as brine dewatering subsystems, were added to further process life support system byproducts to recover resources. Physicochemical and biological systems can be integrated satisfactorily to achieve desired levels of closure. Imbalances between system components, such as differences in metabolic quotients between human crews and plants, must be addressed. Each subsystem or component that is added to increase closure will likely have added costs, ranging from initial launch mass, power, thermal, crew time, byproducts, etc., that must be factored into break even analysis. Achieving life support system closure while maintaining control of total mass and system complexity will be a challenge.

Ewert, Michael K.↗
NASA NTRS2007

Ceramic Integration Technologies for Energy and Aerospace Applications

Robust and affordable integration technologies for advanced ceramics are required to improve the performance, reliability, efficiency, and durability of components, devices, and systems based on them in a wide variety of energy, aerospace, and environmental applications. Many thermochemical and thermomechanical factors including joint design, analysis, and optimization must be considered in integration of similar and dissimilar material systems.

Singh, Mrityunjay↗
NASA NTRS2010

Representation of the Physiological Factors Contributing to Postflight Changes in Functional Performance Using Motion Analysis Software

Astronauts experience changes in multiple physiological systems due to exposure to the microgravity conditions of space flight. To understand how changes in physiological function influence functional performance, a testing procedure has been developed that evaluates both astronaut postflight functional performance and related physiological changes. Astronauts complete seven functional and physiological tests. The objective of this project is to use motion tracking and digitizing software to visually display the postflight decrement in the functional performance of the astronauts. The motion analysis software will be used to digitize astronaut data videos into stick figure videos to represent the astronauts as they perform the Functional Tasks Tests. This project will benefit NASA by allowing NASA scientists to present data of their neurological studies without revealing the identities of the astronauts.

Parks, Kelsey↗
NASA NTRS2011

Design and Analysis of a Stiffened Composite Structure Repair Concept

A design and analysis of a repair concept applicable to a stiffened thin-skin composite panel based on the Pultruded Rod Stitched Efficient Unitized Structure is presented. Since the repair concept is a bolted repair using metal components, it can easily be applied in the operational environment. Initial analyses are aimed at validating the finite element modeling approach by comparing with available test data. Once confidence in the analysis approach is established several repair configurations are explored and the most efficient one presented. Repairs involving damage to the top of the stiffener alone are considered in addition to repairs involving a damaged stiffener, flange and underlying skin. High fidelity finite element modeling techniques such as mesh-independent definition of compliant fasteners, elastic-plastic metallic material properties and geometrically nonlinear analysis are utilized in the effort. The results of the analysis are presented and factors influencing the design are assessed and discussed.

Przekop, Adam↗
NASA NTRS2012

Validation of Lower-Bound Estimates for Compression-Loaded Cylindrical Shells

The traditional approach used in the design of stability critical thin-walled circular cylin- ders, is to reduce unconservative buckling load predictions with an empirical knockdown factor. An alternative analysis-based approach to determine a lower bound buckling load for cylinders under axial compression is to use a lateral perturbation load to create an initial imperfection and determine the buckling load while that load is applied. This paper describes a preliminary e ort to develop a test capability to verify this approach. Results from tests of three aluminum alloy cylinders are described and compared to nite element predictions.

Haynie, Waddy T.↗
NASA NTRS2015

Design Considerations for a Crewed Mars Ascent Vehicle

Exploration architecture studies identified the Mars Ascent Vehicle (MAV) as one of the largest "gear ratio" items in a crewed Mars mission. Because every kilogram of mass ascended from the Martian surface requires seven kilograms or more of ascent propellant, it is desirable for the MAV to be as small and lightweight as possible. Analysis identified four key factors that drive MAV sizing: 1) Number of crew: more crew members require more equipment-and a larger cabin diameter to hold that equipment-with direct implications to structural, thermal, propulsion, and power subsystem mass. 2) Which suit is worn during ascent: Extravehicular Activity (EVA) type suits are physically larger and heavier than Intravehicular Activity (IVA) type suits and because they are less flexible, EVA suits require more elbow-room to maneuver in and out of. An empty EVA suit takes up about as much cabin volume as a crew member. 3) How much time crew spends in the MAV: less than about 12 hours and the MAV can be considered a "taxi" with few provisions for crew comfort. However, if the crew spends more than 12 consecutive hours in the MAV, it begins to look like a Habitat requiring more crew comfort items. 4) How crew get into/out of the MAV: ingress/egress method drives structural mass (for example, EVA hatch vs. pressurized tunnel vs. suit port) as well as consumables mass for lost cabin atmosphere, and has profound impacts on surface element architecture. To minimize MAV cabin mass, the following is recommended: Limit MAV usage to 24 consecutive hours or less; discard EVA suits on the surface and ascend wearing IVA suits; Limit MAV functionality to ascent only, rather than dual-use ascent/habitat functions; and ingress/egress the MAV via a detachable tunnel to another pressurized surface asset.

Rucker, Michelle A.↗
NASA NTRS2001

Carbon Dioxide Collection and Purification System for Mars

One of the most abundant resources available on Mars is the atmosphere. The primary constituent, carbon dioxide, can be used to produce a wide variety of consumables including propellants and breathing air. The residual gases can be used for additional pressurization tasks including supplementing the oxygen partial pressure in human habitats. A system is presented that supplies pure, high-pressure carbon dioxide and a separate stream of residual gases ready for further processing. This power-efficient method freezes the carbon dioxide directly from the atmosphere using a pulse-tube cryocooler. The resulting CO2 mass is later thawed in a closed pressure vessel, resulting in a compact source of liquefied gas at the vapor pressure of the bulk fluid. Results from a demonstration system are presented along with analysis and system scaling factors for implementation at larger scales. Trace gases in the Martian atmosphere challenge the system designer for all carbon dioxide acquisitions concepts. The approximately five percent of other gases build up as local concentrations of CO2 are removed, resulting in diminished performance of the collection process. The presented system takes advantage of this fact and draws the concentrated residual gases away as a useful byproduct. The presented system represents an excelient volume and mass solution for collecting and compressing this valuable Martian resource. Recent advances in pulse-tube cryocooler technology have enabled this concept to be realized in a reliable, low power implementation.

Clark, D. Larry↗
NASA NTRS2016

Influence of Population Variation of Physiological Parameters in Computational Models of Space Physiology

The earliest manifestations of Visual Impairment and Intracranial Pressure (VIIP) syndrome become evident after months of spaceflight and include a variety of ophthalmic changes, including posterior globe flattening and distension of the optic nerve sheath. Prevailing evidence links the occurrence of VIIP to the cephalic fluid shift induced by microgravity and the subsequent pressure changes around the optic nerve and eye. Deducing the etiology of VIIP is challenging due to the wide range of physiological parameters that may be influenced by spaceflight and are required to address a realistic spectrum of physiological responses. Here, we report on the application of an efficient approach to interrogating physiological parameter space through computational modeling. Specifically, we assess the influence of uncertainty in input parameters for two models of VIIP syndrome: a lumped-parameter model (LPM) of the cardiovascular and central nervous systems, and a finite-element model (FEM) of the posterior eye, optic nerve head (ONH) and optic nerve sheath. Methods: To investigate the parameter space in each model, we employed Latin hypercube sampling partial rank correlation coefficient (LHSPRCC) strategies. LHS techniques outperform Monte Carlo approaches by enforcing efficient sampling across the entire range of all parameters. The PRCC method estimates the sensitivity of model outputs to these parameters while adjusting for the linear effects of all other inputs. The LPM analysis addressed uncertainties in 42 physiological parameters, such as initial compartmental volume and nominal compartment percentage of total cardiac output in the supine state, while the FEM evaluated the effects on biomechanical strain from uncertainties in 23 material and pressure parameters for the ocular anatomy. Results and Conclusion: The LPM analysis identified several key factors including high sensitivity to the initial fluid distribution. The FEM study found that intraocular pressure and intracranial pressure had dominant impact on the peak strains in the ONH and retro-laminar optic nerve, respectively; optic nerve and lamina cribrosa stiffness were also important. This investigation illustrates the ability of LHSPRCC to identify the most influential physiological parameters, which must therefore be well-characterized to produce the most accurate numerical results.

biomechanics↗
NASA NTRS2018

Use of Shuttle Heritage Hardware in Space Launch System (SLS) Application-Structural Assessment

NASA is moving forward with the development of the next generation system of human spaceflight to meet the Nation's goals of human space exploration. To meet these goals, NASA is aggressively pursuing the development of an integrated architecture and capabilities for safe crewed and cargo missions beyond low-Earth orbit. Two important tenets critical to the achievement of NASA's strategic objectives are Affordability and Safety. The Space Launch System (SLS) is a heavy-lift launch vehicle being designed/developed to meet these goals. The SLS Block 1 configuration (Figure 1) will be used for the first Exploration Mission (EM-1). It utilizes existing hardware from the Space Shuttle inventory, as much as possible, to save cost and expedite the schedule. SLS Block 1 Elements include the Core Stage, "Heritage" Boosters, Heritage Engines, and the Integrated Spacecraft and Payload Element (ISPE) consisting of the Launch Vehicle Stage Adapter (LVSA), the Multi-Purpose Crew Vehicle (MPCV) Stage Adapter (MSA), and an Interim Cryogenic Propulsion Stage (ICPS) for Earth orbit escape and beyond-Earth orbit in-space propulsive maneuvers. When heritage hardware is used in a new application, it requires a systematic evaluation of its qualification. In addition, there are previously-documented Lessons Learned (Table -1) in this area cautioning the need of a rigorous evaluation in any new application. This paper will exemplify the systematic qualification/assessment efforts made to qualify the application of Heritage Solid Rocket Booster (SRB) hardware in SLS. This paper describes the testing and structural assessment performed to ensure the application is acceptable for intended use without having any adverse impact to Safety. It will further address elements such as Loads, Material Properties and Manufacturing, Testing, Analysis, Failure Criterion and Factor of Safety (FS) considerations made to reach the conclusion and recommendation.

Aggarwal, Pravin↗
NASA NTRS2014

Controller Inhibition of Automated Conflict Resolutions in a Maximum NextGen Condition

With the continued projection of increases in air traffic density, operations in the National Airspace System are expected to exceed human capabilities in the near future. In order to address the bottleneck of human workload capacity, highly automated safety-critical systems are under development to support air traffic controllers. A human-in-the-loop experiment examined controllers transition through four NextGen automation stages: Current-Day, Minimum, Moderate, and Maximum. Maximum NextGen simulated a fully automated environment where the automation was responsible for detecting and resolving conflicts within simulation parameters in high-density airspace. By allocating these tasks to the automation, the controllers task changed. The human moved to primarily a supervisory position- typically only regaining control over separation assurance tasks during conflict situations deferred by the automation. While tasks were allocated a-priori between the controller and automated agent, controllers maintained authority to inhibit the automation from interacting with particular aircraft. Preliminary work is complete, where significant differences were found in inhibition frequency between simulation participants. However, the contexts in which the controllers inhibited the automation, and their reasons for doing so, remain unclear. This analysis attempts to identity factors contributing to human controllers inhibition of the automation in the Maximum NextGen condition.

adaptable automation↗
NASA NTRS2020

Open Advanced Air Mobility Project Vertiport and Route Decision Support Tool

The expected rise of Urban Air Mobility (UAM) presents local and regional planners with unique challenges. Aviation-based urban transportation requires analysis of new planning factors in addition to traditional factors. For example, the planner must be able to analyze community impacts (e.g. aircraft noise) and restrictions (e.g. airspace restrictions, terrain avoidance). This presentation presents a software modeling tool to address these planning challenges.

Shapiro, David L.↗
NASA NTRSDate not supplied

Dust Solution Testing Initiative (DuSTI): Infusing Commercial Off the Shelf Dust Mitigation Technologies with NASA Practices

Dust is one of the most significant hazards to human lunar exploration. However, since the Apollo program concluded, limited research has been performed on lunar dust mitigation technologies. The safety of the crew members and sustainability of habitats, science, and supporting hardware depend on effective dust mitigation techniques and technologies. As NASA pursues a new generation of lunar missions with the Artemis program, the project team will pursue dust mitigation solutions with the Dust Solution Testing Initiative (DuSTI). DuSTI is a lunar dust mitigation effort that involves performing tests on commercial off the shelf (COTS) technologies over FY21. DuSTI will preform component and subsystem tests in dusty environments for up to five technologies with high potential. The specific technologies identified for study were selected based on several factors, including a market analysis of current terrestrial dust mitigation applications, availability of the technology, accessibility of various testing facilities, and cost of procurement. These technologies support the active and passive dust mitigation requirements of filtration systems, electro-mechanical systems, electro-static systems, surface coatings, textiles, and silicone polymers. Technology Readiness Level (TRL) will be increased by validating components in relevant environments. For example, if the COTS technology is at a TRL 9 for terrestrial use but at a 4-5 TRL for use in the lunar environment, we will test that technology in a lunar dust environment to increase the TRL for use on the Moon.

lunar dust↗