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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 1,153 records · Page 64

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NASA NTRS1986

Evaluation of multilayer printed wiring boards by metallographic techniques: An illustrated guide to the preparation and inspection of plated-through hole test coupons based on the requirements of Mil-P-55110D

This work is an illustrated handbook containing the rationale and procedure for the evaluation of multilayer printed wiring board construction integrity with respect to plated-through holes in accordance with the requirements of MIL-P-55110D, Printed Wiring Boards. It is intended as a practical aid for those concerned with determining the construction integrity of multilayer boards for high reliability applications. Photomicrographs of cross sectioned holes illustrate defect types, acceptable and unacceptable conditions, and methods of measurement. A procedure for specimen preparation is given, and appropriate paragraphs of the military specification are included and explained.

Jellison, J.↗

NASA NTRS1985

Analyses and tests for design of an electro-impulse de-icing system

De-icing of aircraft by using the electro-magnetic impulse phenomenon was proposed and demonstrated in several European countries. However, it is not available as a developed system due to lack of research on the basic physical mechanisms and necessary design parameters. The de-icing is accomplished by rapidly discharging high voltage capacitors into a wire coil rigidly supported just inside the aircraft skin. Induced eddy currents in the skin create a repulsive force resulting in a hammer-like force which cracks, de-bonds, and expels ice on the skin surface. The promised advantages are very low energy, high reliability of de-icing, and low maintenance. Three years of Electo-Impulse De-icing (EIDI) research is summarized and the analytical studies and results of testing done in the laboratory, in the NASA Icing Research Tunnel, and in flight are presented. If properly designed, EIDI was demonstrated to be an effective and practical ice protection system for small aircraft, turbojet engine inlets, elements of transport aircraft, and shows promise for use on helicopter rotor blades. Included are practical techniques of fabrication of impulse coils and their mountings. The use of EIDI with nonmetallic surface materials is also described.

Zumwalt, G. W.↗

NASA NTRS1985

Design considerations for a gas microcontroller

This paper discusses some of the design problems that we are now addressing in considering a microcontroller for our upcoming GAS payload. We will be using microcontrollers to run our experiments and collect and store the data from those experiments. microcontroller are to be small , lightweight, have low power consumption, and high reliability. This paper will discuss some of the solutions that we have developed to meet these design requirements. still in the design stage and our final design may change from what we have now. We are continuing to look for new integrated circuits that will do what we need all in one package.

Douglas A. Ritter↗

NASA NTRS1986

The new 34-meter antenna

The new 34-m high efficiency Azimuth - Elevation antenna configuration, including its features, dynamic characteristics and performance at 8.4-GHz frequencies is described. The current-technology features of this antenna produce a highly reliable configuration by incorporation of a main wheel and track azimuth support, central pintle pivot bearing, close tolerance surface panels and all-welded construction. Also described are basic drive controls that, as slaved to three automatic microprocessors, provide accurate and safe control of the antenna's steering tasks. At this time antenna installations are completed at Goldstone and Canberra and have operationally supported the Voyager - Uranus encounter. A third installation is being constructed currently in Madrid and is scheduled for completion in late 1986.

Pompa, M. F.↗

NASA NTRS1986

Plasma contactor performance characterization

The plasma contactor performance is outlined. Some performance objectives are given including expellant compatibility, high electron production capability, high ion production capability, high reliability for starting and operation, passive emission control, switchover capability between ion/electron emission, low ion and electron energies, low system mass, and low expellant consumption rate. The basic elements of the hollow cathode are shown along with key features of the plasma source.

Wilbur, P.↗

NASA NTRS1986

Parametric and cycle tests of a 40-A-hr bipolar nickel-hydrogen battery

A series of tests was performed to characterize battery performance relating to certain operating parameters which included charge current, discharge current, temperature and pressure. The parameters were varied to confirm battery design concepts and to determine optimal operating conditions. Spacecraft power requirements are constantly increasing. Special spacecraft such as the Space Station and platforms will require energy storage systems of 130 and 25 kWh, respectively. The complexity of these high power systems will demand high reliability, and reduced mass and volume. A system that uses batteries for storage will require a cell count in excess of 400 units. These cell units must then be assembled into several batteries with over 100 cells in a series connected string. In an attempt to simplify the construction of conventional cells and batteries, the NASA Lewis Research Center battery systems group initiated work on a nickel-hydrogen battery in a bipolar configuration in early 1981. Features of the battery with this bipolar construction show promise in improving both volumetric and gravimetric energy densities as well as thermal management. Bipolar construction allows cooling in closer proximity to the cell components, thus heat removal can be accomplished at a higher rejection temperature than conventional cell designs. Also, higher current densities are achievable because of low cell impedance. Lower cell impedance is achieved via current flow perpendicular to the electrode face, thus reducing voltage drops in the electrode grid and electrode terminals tabs.

Cataldo, R. L.↗

NASA NTRS1985

Systems approach to software fault tolerance

Computing systems are employed for aerospace applications with high reliability requirements. In order to provide the needed reliability, it was necessary to make use of computing systems with fault-tolerance characteristics. Traditionally, fault tolerance is achieved through the use of hardware redundance. However, fault-tolerant techniques based on suitable software design considerations have also been developed. The present paper is concerned with the major issues arising in the context of an application of fault-tolerant software techniques to dynamic systems. Attention is given to fault-tolerant flight software, software component stability, system stability with fault-tolerant software, the preservation of functional performance, N-version vs. recovery blocks in flight software, systems-based software, static and dynamic models, static and dynamic consistency tests, and recovery block initialization.

Caglayan, A. K.↗

NASA NTRS1985

Lunar base - A stepping stone to Mars

Basic elements of technology and programmatic development are identified that appear relevant to the Case for Mars, starting from a base on the moon. The moon is a logical stepping stone toward human exploration of Mars because a lunar base can provide the first test of human ability to use the resources of another planetary body to provide basic materials for life support. A lunar base can provide the first long-term test of human capability to work and live in a reduced (but not zero) gravity field. A lunar base requires creation of the elements of a space transportation system that will be necessary to deliver large payloads to Mars and the space operations capability and experience necessary to carry out a Mars habitation program efficiently and with high reliability. A lunar base is feasible for the first decade of the 21st Century. Scenarios have been studied that provide advanced capability by 2015 within budget levels that are less than historical U.S. space expenditures (Apollo). Early return on the investment in terms of knowledge, practical experience and lunar products are important in gaining momentum for an expanded human exploration of the solar system and the eventual colonization of Mars.

Duke, M. B.↗

NASA NTRS1985

Artificial intelligence - NASA

Artificial Intelligence (AI) represents a vital common space support element needed to enable the civil space program and commercial space program to perform their missions successfully. It is pointed out that advances in AI stimulated by the Space Station Program could benefit the U.S. in many ways. A fundamental challenge for the civil space program is to meet the needs of the customers and users of space with facilities enabling maximum productivity and having low start-up costs, and low annual operating costs. An effective way to meet this challenge may involve a man-machine system in which artificial intelligence, robotics, and advanced automation are integrated into high reliability organizations. Attention is given to the benefits, NASA strategy for AI, candidate space station systems, the Space Station as a stepping stone, and the commercialization of space.

Erickson, J. D.↗

NASA NTRS1986

An approximation formula for a class of fault-tolerant computers

An approximation formula is derived for the probability of failure for fault-tolerant process-control computers. These computers use redundancy and reconfiguration to achieve high reliability. Finite-state Markov models capture the dynamic behavior of component failure and system recovery, and the approximation formula permits an estimation of system reliability by an easy examination of the model.

White, A. L.↗

NASA NTRS1986

An analysis of estimation of pulmonary blood flow by the single-breath method

The single-breath method represents a simple noninvasive technique for the assessment of capillary blood flow across the lung. However, this method has not gained widespread acceptance, because its accuracy is still being questioned. A rigorous procedure is described for estimating pulmonary blood flow (PBF) using data obtained with the aid of the single-breath method. Attention is given to the minimization of data-processing errors in the presence of measurement errors and to questions regarding a correction for possible loss of CO2 in the lung tissue. It is pointed out that the estimations are based on the exact solution of the underlying differential equations which describe the dynamics of gas exchange in the lung. The reported study demonstrates the feasibility of obtaining highly reliable estimates of PBF from expiratory data in the presence of random measurement errors.

Srinivasan, R.↗

NASA NTRS1987

Braking System for Wind Turbines

Operating turbine stopped smoothly by fail-safe mechanism. Windturbine braking systems improved by system consisting of two large steel-alloy disks mounted on high-speed shaft of gear box, and brakepad assembly mounted on bracket fastened to top of gear box. Lever arms (with brake pads) actuated by spring-powered, pneumatic cylinders connected to these arms. Springs give specific spring-loading constant and exert predetermined load onto brake pads through lever arms. Pneumatic cylinders actuated positively to compress springs and disengage brake pads from disks. During power failure, brakes automatically lock onto disks, producing highly reliable, fail-safe stops. System doubles as stopping brake and "parking" brake.

Krysiak, J. E.↗

NASA NTRS1986

Laser-powered MHD generators for space application

Magnetohydrodynamic (MHD) energy conversion systems of the pulsed laser-supported detonation (LSD) wave, plasma MHD, and liquid-metal MHD (LMMHD) types are assessed for their potential as space-based laser-to-electrical power converters. These systems offer several advantages as energy converters relative to the present chemical, nuclear, and solar devices, including high conversion efficiency, simple design, high-temperature operation, high power density, and high reliability. Of these systems, the Brayton cycle liquid-metal MHD system appears to be the most attractive. The LMMHD technology base is well established for terrestrial applications, particularly with regard to the generator, mixer, and other system components. However, further research is required to extend this technology base to space applications and to establish the technology required to couple the laser energy into the system most efficiently. Continued research on each of the three system types is recommended.

Jalufka, N. W.↗

NASA NTRS1984

Experiences performing conceptual design optimization of transport aircraft

Optimum Preliminary Design of Transports (OPDOT) is a computer program developed at NASA Langley Research Center for evaluating the impact of new technologies upon transport aircraft. For example, it provides the capability to look at configurations which have been resized to take advantage of active controls and provide and indication of economic sensitivity to its use. Although this tool returns a conceptual design configuration as its output, it does not have the accuracy, in absolute terms, to yield satisfactory point designs for immediate use by aircraft manufacturers. However, the relative accuracy of comparing OPDOT-generated configurations while varying technological assumptions has been demonstrated to be highly reliable. Hence, OPDOT is a useful tool for ascertaining the synergistic benefits of active controls, composite structures, improved engine efficiencies and other advanced technological developments. The approach used by OPDOT is a direct numerical optimization of an economic performance index. A set of independent design variables is iterated, given a set of design constants and data. The design variables include wing geometry, tail geometry, fuselage size, and engine size. This iteration continues until the optimum performance index is found which satisfies all the constraint functions. The analyst interacts with OPDOT by varying the input parameters to either the constraint functions or the design constants. Note that the optimization of aircraft geometry parameters is equivalent to finding the ideal aircraft size, but with more degrees of freedom than classical design procedures will allow.

Arbuckle, P. D.↗

NASA NTRS1986

Emitted vibration measurement device and method

This invention is directed to a method and apparatus for measuring emitted vibrational forces produced by a reaction wheel assembly due to imbalances, misalignment, bearing defects and the like. The apparatus includes a low mass carriage supported on a large mass base. The carriage is in the form of an octagonal frame having an opening which is adapted for receiving the reaction wheel assembly supported thereon by means of a mounting ring. The carriage is supported on the base by means of air bearings which support the carriage in a generally frictionless manner when supplied with compressed air from a source. A plurality of carriage brackets and a plurality of base blocks provided for physical coupling of the base and carriage. The sensing axes of the load cells are arranged generally parallel to the base and connected between the base and carriage such that all of the vibrational forces emitted by the reaction wheel assembly are effectively transmitted through the sensing axes of the load cells. In this manner, a highly reliable and accurate measurment of the vibrational forces of the reaction wheel assembly can be had. The output signals from the load cells are subjected to a dynamical analyzer which analyzes and identifies the rotor and spin bearing components which are causing the vibrational forces.

Gisler, G. L.↗

NASA NTRS1986

Shutter mechanism for calibration of the cryogenic diffused infrared background experiment (DIRBE) instrument

The design requirements, the design, the assembly and alignment, and the test program for a shutter mechanism which must operate at cryogenic temperature and draw less than 1.0 milliwatt are discussed. The design solution to meet these requirements is a device that positions a mirror with repeated accuracy, has no wearing surfaces, and operates at 2.0 K. The unique feature of this device is the simplicity of the mechanism, thus obtaining high reliability.

Tyler, Allen↗

NASA NTRS1986

Mars landing mission: A structural approach

A Mars landing mission in 2000 presents a structural challenge. Earlier studies have indicated that a Mars landing was then feasible using current structural techniques. Since these earlier studies, technology advances were made to enhance the capability. Lighter and stronger materials, large structures programs, and supercomputers now exist and even greater advances are expected. The feasibility of a Mars landing does not depend on the structure. If the space travelers can withstand the trip, the necessary structures can be provided to deliver them. If artificial gravity is required the structure can also provide for it. The structural challenge is to provide structural designs that are lightweight with high reliability. In order to do this advanced technology must be utilized to the fullest on all structural elements.

Fuller, Stan↗

NASA NTRS1987

CARE 3 user-friendly interface user's guide

CARE 3 predicts the unreliability of highly reliable reconfigurable fault-tolerant systems that include redundant computers or computer systems. CARE3MENU is a user-friendly interface used to create an input for the CARE 3 program. The CARE3MENU interface has been designed to minimize user input errors. Although a CARE3MENU session may be successfully completed and all parameters may be within specified limits or ranges, the CARE 3 program is not guaranteed to produce meaningful results if the user incorrectly interprets the CARE 3 stochastic model. The CARE3MENU User Guide provides complete information on how to create a CARE 3 model with the interface. The CARE3MENU interface runs under the VAX/VMS operating system.

Martensen, A. L.↗