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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

The ASSIST trial: Acute effects of manipulating strength exercise volume on insulin sensitivity in obese adults: A protocol for a randomized controlled, crossover, clinical trial

Type 2 diabetes mellitus is a disease in which insulin action is impaired, and an acute bout of strength exercise can improve insulin sensitivity. Current guidelines for strength exercise prescription suggest that 8 to 30 sets could be performed, although it is not known how variations in exercise volume impact insulin sensitivity. Additionally, this means an almost 4-fold difference in time commitment, which might directly impact an individual’s motivation and perceived capacity to exercise. This study will assess the acute effects of high- and low-volume strength exercise sessions on insulin sensitivity. After being thoroughly familiarized, 14 obese individuals of both sexes (>40 year old) will undergo 3 random experimental sessions, with a minimum 4-day washout period between them: a high-volume session (7 exercises, 3 sets per exercise, 21 total sets); a low-volume session (7 exercises, 1 set per exercise, 7 total sets); and a control session, where no exercise will be performed. Psychological assessments (feeling, enjoyment, and self-efficacy) will be performed after the sessions. All sessions will be held at night, and the next morning, an oral glucose tolerance test will be performed in a local laboratory, from which indexes of insulin sensitivity will be derived. We believe this study will aid in strength exercise prescription for individuals who claim not to have time to exercise or who perceive high-volume strength exercise intimidating to adhere to. This trial was prospectively registered.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2021

Low-Cost Aero Technology Demonstrations

The main focus of this work was to demonstrate the use of polymeric additive manufacturing (AM) to create tooling for both preforming and consolidation. Polymeric tooling was utilized where both modest and higher pressures are used for part consolidation. The key focus for the AM tooling development was for fabrication of complex structures such as ducting, C-channel stiffened skins, and airfoils where conventional male tooling would typically be trapped in the cured part. The AM tooling was evaluated for use as a tool master used to fabricate and re-shape deformable/re-formable mandrels based on SpinTech’s shape memory composite technology known as Smart Tooling. The AM tooling was also evaluated for use as a mold for composite infusion and consolidation. Key performance parameters were tracked for project schedule completion with each step comprising of “art to part” cycle time, cost, and model fidelity for dimensions, performance, and cost. The primary focus of this demonstration was to determine if a 50% cost reduction was achievable, for each AM tooling-set, as compared to conventional processes. UDRI leveraged project partner SpinTech, who manufactures tools and parts in these categories and thus provided a baseline regarding current best practices and provided valuable feedback during the entirety of this demonstration. This demonstration primarily focused on the use of AM tooling for fabrication of three composite component structures which are typically utilized in aircraft and comprise salient geometric features of broad interest. These components are often tooling intensive and have features requiring extraction of male tools which are usually trapped by the geometry. The three structures selected by the team included: 1) A one-piece airfoil shell comprised of compound contours where male tooling would be trapped unless the part were manufactured in two halves as is typically the case. 2) A one-piece duct used for air handling, comprised of compound contours where male tooling would be trapped unless the part were manufactured in two halves, or a washout mandrel were to be used. 3) A co-cured C-channel stiffened skin where typically C-channels would be individually manufactured and then bonded to a cured skin. The demonstration was comprised of three main tasks: • Task 1: AM Tool Feasibility Study – ensure the AM tooling meets the performance requirements as specified by SpinTech to match baseline performance. • Task 2: Complex Tool Demonstration – Fabricate tooling, preforms, and parts representative of an airfoil and duct. • Task 3: Large Aerostructure Fabrication Demonstration – Fabricate tooling, preforms, and part representative of a C-channel stiffened skin. With the conclusion of this project, a decision tree was developed to determine the key considerations necessary to determine if use of AM tooling for the three selected structures was able to attain the same quality as historically achieved on metallic tooling, while providing a significant cost reduction.

36 MATERIALS SCIENCE↗
NASA NTRS1971

Motion effects on an IFR hovering task: Analytical predictions and experimental results

An analytical pilot model incorporating the effects of motion cues and display scanning and sampling is tested by comparing predictions against experimental results on a moving base simulator. The simulated task is that of precision hovering of a VTOL having varying amounts of rate damping, and using separated instrument displays. Motion cue effects are investigated by running the experiment under fixed and moving base conditions, the latter in two modes; full motion, and angular motion only. Display scanning behavior is measured on some of the runs. The results of the program show that performance is best with angular motion only, most probably because a g-vector tilt cue is available to the pilot in this motion condition. This provides an attitude indication even when not visually fixating the attitude display. Vestibular threshold effects are also present in the results because of the display scaling used to permit hovering position control within the motion simulator limits; no washouts are used in the simulator drive signals. The IFR nature of the task results in large decrements in pilot opinion and performance relative to VFR conditions because of the scanning workload. Measurements of scanning behavior are sensitive to motion conditions and show more attention to attitude control under fixed base conditions.

Ringland, R. F.↗
NASA NTRS1972

Visibility of lunar surface features - Apollo 14 orbital observations and lunar landing.

Description of an in-flight visibility test conducted during the Apollo 14 mission for the purpose of validating and extending the mathematical visibility models used previously in the course of the Apollo program to examine the constraints on descent operations imposed by lunar visibility limitations. Following a background review of the effects on mission planning of the visibility limitations due to downsun lunar surface detail 'washout' and a discussion of the visibility prediction techniques previously used for studying lunar visibility problems, the visibility test rationale and procedures are defined and the test results presented. The results appear to confirm the validity of the visibility prediction techniques employed in lunar visibility problem studies. These results provide also a basis for improving the accuracy of the prediction techniques by appropriate modifications.

Ziedman, K.↗
NASA NTRS1973

Coordinated adaptive filters for motion simulators.

A new approach to providing motion drive signals to a flight simulator utilizing coordinated adaptive filters is presented. Some motivation for the use of coordinated washout is discussed, along with conditions that determine the burden of coordination. The coordinated adaptive filters are derived, based on continuous steepest descent, and the application of the filters to simulated flight data is demonstrated.

Parrish, R. V.↗
NASA NTRS1974

An experimental and theoretical study of low-aspect ration swept and oblique wings at Mach numbers between 0.6 and 1.4

Experimental forces and moments for two wing-body combinations having (a) a swept wing and (b) an oblique wing are compared. At all Mach numbers, the oblique wing (at its optimum sweep angle) had higher maximum lift-to-drag ratios than the fixed, swept wing. At high angles of attack, the direction of the pitching or rolling tendencies of the oblique wing was a function of the spanwise distribution of wing bend or washout for the two bends being investigated. At low angles of attack, linear theory gave satisfactory predictions of the subsonic lift-curve slope, the aerodynamic-center travel with Mach number, and the maximum lift-to-drag ratio.

Hopkins, E. J.↗
NASA NTRS1974

A motion-constraint logic for moving-base simulators based on variable filter parameters

A motion-constraint logic for moving-base simulators has been developed that is a modification to the linear second-order filters generally employed in conventional constraints. In the modified constraint logic, the filter parameters are not constant but vary with the instantaneous motion-base position to increase the constraint as the system approaches the positional limits. With the modified constraint logic, accelerations larger than originally expected are limited while conventional linear filters would result in automatic shutdown of the motion base. In addition, the modified washout logic has frequency-response characteristics that are an improvement over conventional linear filters with braking for low-frequency pilot inputs. During simulated landing approaches of an externally blown flap short take-off and landing (STOL) transport using decoupled longitudinal controls, the pilots were unable to detect much difference between the modified constraint logic and the logic based on linear filters with braking.

Miller, G. K., Jr.↗
NASA NTRS1974

Man-systems evaluation of moving base vehicle simulation motion cues

A motion cue investigation program is reported that deals with human factor aspects of high fidelity vehicle simulation. General data on non-visual motion thresholds and specific threshold values are established for use as washout parameters in vehicle simulation. A general purpose similator is used to test the contradictory cue hypothesis that acceleration sensitivity is reduced during a vehicle control task involving visual feedback. The simulator provides varying acceleration levels. The method of forced choice is based on the theory of signal detect ability.

Kirkpatrick, M.↗
NASA NTRS1976

Effect of wing bend on the experimental force and moment characteristics of an oblique wing

Static longitudinal and lateral/directional force and moment characteristics are presented for an elliptical oblique wing mounted on top of a Sears-Haack body of revolution. The wing had an aspect ratio of 6 (based on the unswept span) and was tested at various sweep angles relative to the body axis ranging from 0 to 60 deg. In an attempt to create more symmetrical spanwise wing stalling characteristics, both wing panels were bent upward to produce washout on the trailing wing panel and washing on the leading wing panel. Small fluorescent tufts were attached to the wing surface to indicate the stall progression on the wing. The tests were conducted throughout a Mach number range from 0.6 to 1.4 at a constant unit Reynolds number of 8.2 x 10 per meter. The test results indicate that upward bending of the wing panels had only a small effect on the linearity of the moment curves and would require an impractical wing-pivot location at low lift to eliminate the rolling moment resulting from this bending.

Hopkins, E. J.↗
NASA NTRS1974

An automated system for pulmonary function testing

An experiment to quantitate pulmonary function was accepted for the space shuttle concept verification test. The single breath maneuver and the nitrogen washout are combined to reduce the test time. Parameters are defined from the forced vital capacity maneuvers. A spirometer measures the breath volume and a magnetic section mass spectrometer provides definition of gas composition. Mass spectrometer and spirometer data are analyzed by a PDP-81 digital computer.

Mauldin, D. G.↗
NASA NTRS1977

Theoretical Parametric Study of the Relative Advantages of Winglets and Wing-Tip Extensions

This study provides sweeping confirmation, for a wide range of wings, of the recommendations of Whitcomb in NASA TN D-8560. For identical increases in bending moment, a winglet provides a greater gain in induced efficiency than tip extension. Winglet toe angle allows design trades between efficiency and root moment. A winglet shows the greatest benefit when the wing loads are heavy near the tip. Washout diminishes the benefit of either tip modification, and the gain in induced efficiency becomes a function of lift coefficient; thus, heavy wing loadings obtain the greatest benefit from a winglet, and low-speed performance is enhanced even more than cruise performance. Both induced efficiency and bending moment increase with winglet length and outward cant. The benefit of a winglet relative to a tip extension is greatest for a nearly vertical winglet. Root bending moment is proportional to the minimum weight of bending material required in the wing; thus, it is a valid index of the impact of tip modifications on a new wing design.

Aerodynamics↗
NASA NTRS1977

Effect of wing flexibility on the experimental aerodynamic characteristics of an oblique wing

A solid-aluminum oblique wing was designed to deflect considerably under load so as to relieve the asymmetric spanwise stalling that is characteristic of this type of wing by creating washout on the trailing wing panel and washin on the leading wing panel. Experimental forces, and pitching, rolling and yawing moments were measured with the wing mounted on a body of revolution. In order to vary the dynamic pressure, measurements were made at several unit Reynolds numbers, and at Mach numbers. The wing was investigated when unswept (at subsonic Mach numbers only) and when swept 45 deg, 50 deg, and 60 deg. The wing was straight tapered in planform, had an aspect ratio of 7.9 (based on the unswept span), and a profile with a maximum thickness of 4 percent chord. The results substantiate the concept that an oblique wing designed with the proper amount of flexibility self relieves itself of asymmetric spanwise stalling and the associated nonlinear moment curves.

Hopkins, E. J.↗
NASA NTRS1977

Simulation of a synergistic six-post motion system on the flight simulator for advanced aircraft at NASA-Ames

Motion system drive philosophy and corresponding real-time software have been developed for the purpose of simulating the characteristics of a typical synergistic Six-Post Motion System (SPMS) on the Flight Simulator for Advanced Aircraft (FSAA) at NASA-Ames which is a non-synergistic motion system. This paper gives a brief description of these two types of motion systems and the general methods of producing motion cues of the FSAA. An actuator extension transformation which allows the simulation of a typical SPMS by appropriate drive washout and variable position limiting is described.

Bose, S. C.↗
NASA NTRS1977

Theoretical parametric study of the relative advantages of winglets and wing-tip extensions

It was found that for identical increases in bending moment, a winglet provides a greater gain in induced efficiency than a tip extension. Winglet toe-in angle allows design trades between efficiency and root moment. A winglet showed the greatest benefit when the wing loads were heavy near the tip. Washout diminished the benefit of either tip modification, and the gain in induced efficiency became a function of lift coefficient; heavy wing loadings obtained the greatest benefit from a winglet, and low speed performance was enhanced even more than cruise performance. Both induced efficiency and bending moment increased with winglet length and outward cant. The benefit of a winglet relative to a tip extension was greatest for a nearly vertical winglet. Root bending moment was proportional to the minimum weight of bending material required in the wing; it is a valid index of the impact of tip modifications on a new wing design.

Heyson, H. H.↗
NASA NTRS1977

Computed Responses of Several Aircraft to Atmospheric Turbulence and Discrete Wind Shears

The computed RMS and peak responses due to atmospheric turbulence and discrete wind shears, respectively, are presented for several aircraft in different flight conditions. The responses are presented with and without the effects of a typical second order washout filter. A complete set of dimensional stability derivatives for each aircraft/flight condition combination evaluated is also presented.

Jewell, W. F.↗
NASA NTRS1979

Experiments in sensing transient rotational acceleration cues on a flight simulator

Results are presented for two transient motion sensing experiments which were motivated by the identification of an anomalous roll cue (a 'jerk' attributed to an acceleration spike) in a prior investigation of realistic fighter motion simulation. The experimental results suggest the consideration of several issues for motion washout and challenge current sensory system modeling efforts. Although no sensory modeling effort is made it is argued that such models must incorporate the ability to handle transient inputs of short duration (some of which are less than the accepted latency times for sensing), and must represent separate channels for rotational acceleration and velocity sensing.

Parrish, R. V.↗