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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Adrenocortical responses of the Apollo 17 crew members

Changes in adrenal activity of the three Apollo 17 crew members were studied during the 12.55-day mission and during selected post-recovery days. Aldosterone excretion was normal early and elevated later in the mission, probably causing a loss in total body exchangeable potassium. There was decreased 17-hydroxycorticosteroid excretion only during the early mission days for the two moon landers and throughout the mission for the other astronaut. Cortisol excretion was elevated on physically stressful mission days. At recovery, plasma ACTH was elevated without a similar increase in plasma cortisol. Angiotensin I activity was elevated at recovery in only one crewman. This crewman was the only one with a decreased extracellular fluid volume. These results indicate that the mission and its activities affect adrenal function of the crewmen.

Leach, C. S.↗
NASA NTRS1975

Basic results of medical examinations of Soyuz spacecraft crew members

Weightlessness, hypokinesia and intense activity of crew members caused changes in human physiological functions during prolonged space flight as expressed in unusual diurnal rhythms. Microclimate, radiation and the nervous emotional state were not of significance in emergence of human body response reactions.

Gurovskiy, N. N.↗
NASA NTRS1975

Device for use in loading tension members

The indicator is characterized by an elongated elastic body having extended from the opposite ends of threaded shanks adapted to selected tension members. A pair of external shoulders, one of which is axially displaceable relative to the other, and a rigid tubular sleeve interposed between said shoulders are included. Tension is applied to the elastic body for imparting strain. The movable shoulder can be advanced into abutting engagement with the sleeve, whereby the sleeve is placed in compression once the tensile forces are removed from the shanks. A reapplication of tensile forces equal to the initially applied tensile forces removes the sleeve from compression, whereby the sleeve is freed for rotation for thus indicating the magnitude of the applied tensile forces.

Appleberry, W. T.↗
NASA NTRS1977

An optimality criterion for sizing members of heated structures with temperature constraints

A thermal optimality criterion is presented for sizing members of heated structures with multiple temperature constraints. The optimality criterion is similar to an existing optimality criterion for design of mechanically loaded structures with displacement constraints. Effectiveness of the thermal optimality criterion is assessed by applying it to one- and two-dimensional thermal problems where temperatures can be controlled by varying the material distribution in the structure. Results obtained from the optimality criterion agree within 2 percent with results from a closed-form solution and with results from a mathematical programming technique. The thermal optimality criterion augments existing optimality criteria for strength and stiffness related constraints and offers the possibility of extension of optimality techniques to sizing structures with combined thermal and mechanical loading.

Rao, G. V.↗
NASA NTRS1980

Optimal member damper controller design for large space structures

Consideration is given to the selection of velocity feedback gains for individual dampers for the members of a structurally controlled large flexible space structure. The problem is formulated as an optimal output feedback regulator problem, and necessary conditions are derived for minimizing a quadratic performance function. The diagonal nature of the gain matrix is taken into account, along with knowledge of noise covariances. It is pointed out that the method presented offers a systematic approach to the design of a class of controllers for enhancing structural damping, which have significant potential if used in conjunction with a reduced-order optimal controller for rigid-body modes and selected structural modes.

Joshi, S. M.↗
NASA NTRS1982

Documentation for the machine-readable version of a deep objective-prism survey for large Magellanic cloud members

This catalog contains 1273 proven or probable Large Magellanic Cloud (LMC) members, as found on deep objective-prism plates taken with the Curtis Schmidt telescope at Cerro Tololo Inter-American Observatory in Chile. The stars are generally brighter than about photographic magnitude 14. Approximate spectral types were determined by examination of the 580 A/mm objective-prism spectra; approximate 1975 positions were obtained by measuring relative to the 1975 coordinate grids on the Uppsala-Mount Stromlo Atlas of the LMC (Gascoigne and Westerlund 1961), and approximate photographic magnitudes were determined by averaging image density measures from the plates and image-diameter measures on the 'B' charts. The machine-readable version of the LMC survey catalog is described to enable users to read and process the tape file without problems or guesswork.

Warren, W. H., Jr.↗
NASA NTRS1984

Payload crew members' view of Spacelab operations

Various operational aspects of the Spacelab 1 mission are reviewed by the four payload crew members. Two-shift operations, voice communication with ground investigators, joint participation in experiment activity, Spacelab performance, and recent advances are discussed.

Garriott, O. K.↗
NASA NTRS1984

Quantification of Saint-Venant's Principle for a General Prismatic Member

A semi-analytic finite element method for finding the decay rates of edge effects in anisotropic layered plates was extended to the treatment of prismatic members of an arbitrary cross section composed of any number of anisotropic elements. The displacement fields corresponding to the decay rates with positive real part were determined for a homogenous graphite/epoxy plate two units thick. The behavior of a rectangular beam is also considered.

Source record↗
NASA NTRS1987

Member vibration effects on LSS behavior

This paper evaluates the sensitivity of modal characteristics of large deployable lattice-type space structures to joint boundary conditions. The evaluation of joint rotational boundary conditions is accomplished by a review of modal strain energy among elements of the analytic dynamic model. This review shows that space structure designs having no bending energy in lattice members in the low frequency range are insensitive to joint rotational boundary conditions in that frequency range. Evaluation of joint translation boundary conditions is accomplished by the 'modal freeplay method' which is described in this paper. The modal freeplay method relates modal frequency to joint translational freeplay and to amplitude of applied forces.

White, Charles W.↗
NASA NTRS1989

Locating Damaged Members in a Truss Structure Using Modal Test Data: a Demonstration Experiment

On-orbit assessment of large flexible space truss structures can be accomplished, in principle, with dynamic response information, structural identification methods, and model correlation techniques which produce an adjusted mathematical model. In a previously developed approach for damage location, an optimal update of the structure model is formed using the response data, then examined to locate damaged members. An experiment designed to demonstrate and verify the performance of the on-orbit assessment approach uses a laboratory scale model truss structure which exhibits characteristics expected for large space truss structures. Vibration experiments were performed to generate response data for the damaged truss. The damage location approach, analytical work performed in support of the vibration tests, the measured response of the test article, and some preliminary results are described.

Smith, Suzanne Weaver↗
NASA NTRS1989

System identification test using active members

A modal test using active members as the excitation source has been performed on the Precision Truss. Using the step sine testing technique, the frequency response functions are obtained and the modal parameters are extracted by the curve-fitting method. Total of 10 global modes and 3 local modes are obtained. The results are compared with those obtained by the conventional external excitation test.

Chen, Jay-Chung↗
NASA NTRS1989

Locating damaged members in a truss structure using modal test data - A demonstration experiment

An experiment is designed to demonstrate and verify the performance of the on-orbit assessment approach for large flexible space truss structures. The on-orbit assessment approach can be accomplished, in principle, with dynamic response information, structural identification methods, and model correlation techniques which produce an adjusted mathematical model. An optimal update of the structure model is formed using the response data, then examined to locate damaged members. The experiment uses a laboratory scale model truss structure which exhibits characteristics expected for large space truss structures. Vibration experiments are performed to generate response data for the damaged truss. The damage location approach is described, as well as analytical work performed in support of the vibration tests, the measured response of the test article, and some preliminary results.

Smith, Suzanne Weaver↗
NASA NTRS1989

Experimental evaluation of active-member control of precision structures

The results of closed loop experiments that use piezoelectric active-members to control the flexible motion of a precision truss structure are described. These experiments are directed toward the development of high-performance structural systems as part of the Control/Structure Interaction (CSI) program at JPL. The focus of CSI activity at JPL is to develop the technology necessary to accurately control both the shape and vibration levels in the precision structures from which proposed large space-based observatories will be built. Structural error budgets for these types of structures will likely be in the sub-micron regime; optical tolerances will be even tighter. In order to achieve system level stability and local positioning at this level, it is generally expected that some form of active control will be required.

Fanson, James↗
NASA NTRS1989

Rotational velocities of newly discovered, low-mass members of the Alpha Persei cluster

About 30 new, low-mass members of the young open cluster Alpha Persei are identified via a proper-motion study and subsequent photometric and spectroscopic observations. Membership in the cluster is confirmed for a number of the fainter proper-motion candidates from Heckman, Dieckvoss, and Kox (1956). Coordinates, finding charts, BVRI photometry, and rotational velocities are provided for most of the stars. At least two of the stars show peculiar H-alpha emission profiles, with weak but very broad emission wings, and relatively narrow absorption reversals. The rotational velocity distribution for low-mass stars in the Alpha Per cluster are compared with recently derived rotational velocity distributions for T Tauri stars, placing strong constraints on the mechanisms for angular momentum loss during pre-main-sequence evolution.

Stauffer, John R.↗
NASA NTRS1990

On-orbit system identification using active members

The capability to perform accurate on-orbit system identification for both open loop (passive) and closed loop (active) structural systems will be required for future NASA missions; especially those missions which require large precision structures. The information is required to accurately establish the dynamic characteristics of the operational structure in order to adjust the structure itself using the concepts of Adaptive Structures and/or the control system. This paper presents the test results of using Active Members in an adaptive structural system to excite a free-free structure to determine both open and closed loop dynamic characteristics.

Kuo, C. P.↗
NASA NTRS1990

Analysis of elastically tailored viscoelastic damping member

For more than two decades, viscoelastic materials have been commonly used as a passive damping source in a variety of structures because of their high material loss factors. In most of the applications, viscoelastic materials are used either in series with or parallel to the structural load path. The latter is also known as the constrained-layer damping treatment. The advantage of the constrained-layer damping treatment is that it can be incorporated without loss in structural integrity, namely, stiffness and strength. However, the disadvantages are that: (1) it is not the most effective use of the viscoelastic material when compared with the series-type application, and (2) weight penalty from the stiff constraining layer requirement can be excessive. To overcome the disadvantages of the constrained-layer damping treatment, a new approach for using viscoelastic material in axial-type structural components, e.g., truss members, was studied in this investigation.

Chen, G.-S.↗
NASA NTRS1992

Vibration Testing Of Trusses By Use Of Active Members

Report describes experiments conducted to determine whether, in vibration tests of truss structure, active structural members can be used to excite test vibrations yielding accurate data on vibrational modes of structure. Results indicate accuracies equal or exceed those obtained from external-excitation tests.

Chen, Jay Chung↗
NASA NTRS1991

Crew member and instructor evaluations of line oriented flight training

Results obtained from the NASA/UT/LOFT survey of 8300 crew members from four airlines is presented. As simulator training is very expensive and excellence in training is the objective, some effort is justified in evaluating LOFT and in determining what it is about the best scenarios that creates positive effects. Attention is given to the effects of different scenarios, self reports of crew resource management behaviors, organization, fleet and crew position differences.

Wilhelm, John↗