A zone of avoidance catalogue of 2MASS bright galaxies – I. Sample description and analysis
Explore the source record for details and available documents.
A C Schröder↗
SEARCH · Search NASA
Results for “avoidance”
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.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Bandwidth switching is transient-free, avoids loss of loop lock
A circuit, in a wide bandwidth mode, overcomes transient-producing capacitance switching by maintaining an equivalent voltage at all times. Bandwidth switching may be done at any time, and integrity of the loop lock is maintained.
Source record↗
Visual requirements based on minimum obstacle avoidance distance
Operator visual requirements for lunar surface vehicle control
VISUAL CONTROL↗
Avoiding errors from stray radiation in measuring the spectral emittance of diffusely reflecting specimens.
Stray radiation error reduction in spectral emmittance measurements for diffusely reflecting materials
SPECTRAL EMISSION↗
Avoidance and escape behavior controlled by artificial gravity.
Squirrel monkeys escape behavior under centrifuge simulated gravity in excess of earth gravity
Belleville, R. E.↗
Fixed-base visual simulation of obstacle avoidance during terminal descent of advanced Apollo spacecraft with an all-flexible parawing
Fixed-base visual simulation study for ability determination of onboard pilot during landing
Miller, G. K., Jr.↗
Pipe installation technique avoids disturbing work areas
Pipe supports for 0.305 m diameter pipes are pre-hung and an opening is cut in exterior wall of the building. Pipes are welded outside the building and then rolled through the opening into the final location. Technique affords cost and time savings.
Malysz, E. F.↗
Improved circuit avoids premature power transistor failure
Reactor inserted in the base-drive circuit of each power transistor delays the turn-on of one transistor until the other has turned off.
Mclyman, W. T.↗
Visual aspects of air collision avoidance: Computer studies on pilot warning indicator specifications
Techniques of computer calculations used to analyze the potential for improving visual acquisition of collision threats by means of Pilot Warning Indicator systems (PWI) are described. The quantitative effects of PWI resolution and effective range upon the average cumulative probability of detection are presented.
Edwards, G. D.↗
Use of the space shuttle to avoid spacecraft anomalies
An existing data base covering 304 spacecraft of the U.S. space program was analyzed to determine the effect on individual spacecraft failures and other anomalies that the space shuttle might have had if it had been operational throughout the period covered by the data. By combining the results of this analysis, information on the prelaunch activities of selected spacecraft programs, and shuttle capabilities data, the potential impact of the space shuttle on future space programs was derived. The shuttle was found to be highly effective in the prevention or correction of spacecraft anomalies, with 887 of 1,230 anomalies analyzed being favorably impacted by full utilization of shuttle capabilities. The shuttle was also determined to have a far-reaching and favorable influence on the design, development, and test phases of future space programs. This is documented in 37 individual statements of impact.
Source record↗
Avoidance, control, and repair of fatigue damage.
A summary is presented of various methods available to the engineer for dealing with fatigue problems. Design, metallurgical, and service factors are considered. An attempt is made to provide a rational basis for each approach, resorting in each case to an understanding of the fundamental mechanism of the fatigue process.
Manson, S. S.↗
Analysis and design of antennas for air traffic collision avoidance systems.
The analysis and design procedure of an antenna for a CW Doppler radar system being developed for pilot warning of midair collision hazards is presented. The antenna consists of two vertical arrays of half-wavelength dipoles mounted near a circular conducting cylinder. Each vertical array is composed of three vertical dipoles. Each array provides relatively uniform illumination (2.3 dB) in the forward 180-deg angular segment of the horizontal plane and approximately plus or minus 10 to 15 deg coverage in the vertical plane. The antenna could be used in a two-mode operation, either in a standard monopulse radar system (sum and difference amplitude patterns) or in a system where amplitude and phase are the measurable quantities.
Balanis, C. A.↗
Avoidance of Trailing Vortex Hazard by Airport Warning System
In an effort to improve airport traffic operation near jumbo jets, an airport trailing vortex warning system (ATVWS) was developed to predict trailing vortex turbulence. The ATVWS consists of a computer simulator which is compatible with a vortex sensor such as a laser Doppler velocimeter or an acoustic radar. A study of the traffic in one of the ten busiest airports, Atlanta Municipal Airport, provided information on traffic patterns of a statistical nature. With this information, airport traffic patterns can be studied and hazard statistics developed. Based on a careful study of this simulation model, requirements for the development and testing of an ATVWS can be accurately specified.
Rudland, R. S.↗
Contamination avoidance devices for poppettype shutoff valves
The determination of the cycle life is reported of the scal closure of a typical poppet-type shutoff valve in an uncontaminated GH2 environment and then compared this component performance with simulated operation with GN2 and LN2 containing controlled amounts of AL2O3 contaminant particles. The original valve design was tested for contamination damage tolerance characteristics under full-flow and cyclic-operating conditions, redesigned to improve the damage tolerance to contaminants, and then retested. The redesigned valve was found to have acceptable tolerance characteristics under all full-flow conditions and cyclic operation with small (25-75 microns) particulate contamination. The tolerance characteristics of the valve under cyclic conditions with large (75-250 microns) particulate contamination was improved but was not found to be completely satisfactory.
Endicott, D. L.↗
Theoretical study of lift generated vortex sheets designed to avoid roll up
The random motions of the vortex elements behind a wing that sheds a disturbed, translating array of vortices are analyzed. The analysis indicates that the wake would diffuse and decay rapidly when viscosity is present and would produce small rolling moments on encountering aircraft. It was found that comparable results could also be achieved with an array consisting of vortices that are equal in magnitude but which alternate in sign. This observation indicates that random motion can probably be achieved with a variety of stepped loadings.
Rossow, V. J.↗
Contamination damage avoidance concepts for propulsion feed system components.
The potential gain in the reliability of reusable long-term mission vehicles through the minimization of component damage due to the ingestion of particulate contamination by feed system components has been recognized by the NASA-LeRC and MDAC, and a program to investigate these problems has been completed. This investigation covered the determination of the cycle life of a typical 2-in. poppet type of shutoff valve in an uncontaminated GH2 environment and then compared this component performance with simulated operation with GN2 and LN2 containing controlled amounts of AL2O2 contaminant particles. The original valve design was tested for contamination damage tolerance characteristics under full flow and cyclic operating conditions, redesigned to improve the damage tolerance to contaminants and then retested. A second method of approach to damage tolerance control was investigated through the evaluation of various types of particulate separation devices. The study included various types of dynamic separators but did not cover conventional filter assemblies.
Endicott, D. L.↗
Avoidance of stress corrosion susceptibility in high strength aluminum alloys by control of grain boundary and matrix microstructure
The relation of microstructure to the mechanical strength and stress corrosion resistance of highest strength and overaged tempers of BAR and 7050 aluminum alloys was investigated. Comparison is made with previously studied 7075 aluminum alloy. Optical microscopy, transmission electron microscopy, and differential scanning calorimetry were used to characterize the grain morphology, matrix microstructure, and grain boundary microstructure of these tempers. Grain boundary interparticle spacing was significant to stress corrosion crack propagation for all three alloys; increasing interparticle spacing led to increased resistance to crack propagation. In addition, the fire grain size in Bar and 7050 appears to enhance crack propagation. The highest strength temper of 7050 has a comparatively high resistance to crack initiation. Overall stress corrosion behavior is dependent on environment pH, and evaluation over a range of pH is recommended.
Adler, P.↗
Avoiding unrealistic overtest by notching the vibration test specification
The test specifications for spacecraft and components permit test levels to be reduced under a procedure commonly referred to as notching. A summary is provided of the steps required to comply with the notching criterion. Primary structural loads are discussed along with aspect of mathematical modelling of the spacecraft structure, a launch loads analysis, a vibration test loads analysis, and notching methods. It is shown that current, general vibration test specifications are capable of producing unrealistically high spacecraft structural loads.
Hershfeld, D. J.↗