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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 505 records · Page 28
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

An automatic gore panel mapping system

The Automatic Gore Mapping System is being developed to reduce the time and labor costs associated with manufacturing the External Tank. The present chem-milling processes and procedures are discussed. The down loading of the simulation of the system has to be performed to verify that the simulation package will translate the simulation code into robot code. Also a simulation of this system has to be programmed for a gantry robot instead of the articulating robot that is presently in the system. It was discovered using the simulation package that the articulation robot cannot reach all the point on some of the panels, therefore when the system is ready for production, a gantry robot will be used. Also a hydrosensor system is being developed to replace the point-to-point contact probe. The hydrosensor will allow the robot to perform a non-contact continuous scan of the panel. It will also provide a faster scan of the panel because it will eliminate the in-and-out movement required for the present end effector. The system software is currently being modified so that the hydrosensor will work with the system. The hydrosensor consists of a Krautkramer-Branson transducer encased in a plexiglass nozzle. The water stream pumped through the nozzle is the couplant for the probe. Also, software is being written so that the robot will have the ability to draw the contour lines on the panel displaying the out-of-tolerance regions. Presently the contour lines can only be displayed on the computer screens. Research is also being performed on improving and automating the method of scribing the panels. Presently the panels are manually scribed with a sharp knife. The use of a low power laser or water jet is being studied as a method of scribing the panels. The contour drawing pen will be replaced with scribing tool and the robot will then move along the contour lines. With these developments the Automatic Gore Mapping Systems will provide a reduction in time and labor costs associated with manufacturing the External Task. The system also has the potential of inspecting other manufactured parts.

Shiver, John D.↗
NASA NTRS1991

A semi-automated process for the production of custom-made shoes

A more efficient, cost-effective and timely way of designing and manufacturing custom footware is needed. A potential solution to this problem lies in the use of computer-aided design and manufacturing (CAD/CAM) techniques in the production of custom shoes. A prototype computer-based system was developed, and the system is primarily a software entity which directs and controls a 3-D scanner, a lathe or milling machine, and a pattern-cutting machine to produce the shoe last and the components to be assembled into a shoe. The steps in this process are: (1) scan the surface of the foot to obtain a 3-D image; (2) thin the foot surface data and create a tiled wire model of the foot; (3) interactively modify the wire model of the foot to produce a model of the shoe last; (4) machine the last; (5) scan the surface of the last and verify that it correctly represents the last model; (6) design cutting patterns for shoe uppers; (7) cut uppers; (8) machine an inverse mold for the shoe innersole/sole combination; (9) mold the innersole/sole; and (10) assemble the shoe. For all its capabilities, this system still requires the direction and assistance of skilled operators, and shoemakers to assemble the shoes. Currently, the system is running on a SUN3/260 workstation with TAAC application accelerator. The software elements of the system are written in either Fortran or C and run under a UNIX operator system.

Farmer, Franklin H.↗
NASA NTRS1991

Extraterrestrial resources: Implications from terrestrial experience

Terrestrial mining experience indicates that the overwhelming criterion of a potentially economic deposit is its recoverable concentration of the desired mineral or element. Recovery can be based on contrast in physical and/or chemical properties, but processes based on physical properties are typically less expensive. As several processes generally are used in sequence, they have a profound effect on extraction costs. These criteria will also apply to extraterrestrial resources. Although the extreme cost of access to space makes even ordinary materials extremely valuable, this inaccessibility also makes capital and maintenance costs extremely high. The following four development stages will apply, especially with the additional unknowns of an extraterrestrial environment: (1) Exploration for the highest grade of the mineral or element desired (because the extraction plant must be simple, cheap, and rugged to minimize capital and maintenance costs, high grade is extremely important); (2) Laboratory testing of various physical and/or chemical separation techniques on the possible ore to determine if the material can indeed be recovered economically; (3) a pilot plant test, in which a large sample is dug from the deposit to determine excavation rates, power requirements, and equipment wear. (This sample is then run through a pilot mill designed on the basis of the laboratory testing. Pilot plant testing must be carried out at increasing scales, but several trials are generally necessary at each scale before the size of operations can be increased. Moreover, pilot testing is necessary for each new mineral deposit); and (4) Last is the full-scale mine and plant start-up. (New problems invariably occur at this point, but they can be kept to a minimum if the pilot plant tests were realistic). If such a development plan is followed rigorously, major cost overruns, with their potentially disastrous effects on resource developments, can be avoided.

Kuck, David L.↗
NASA NTRS1991

How to determine spiral bevel gear tooth geometry for finite element analysis

An analytical method was developed to determine gear tooth surface coordinates of face milled spiral bevel gears. The method combines the basic gear design parameters with the kinematical aspects for spiral bevel gear manufacturing. A computer program was developed to calculate the surface coordinates. From this data a 3-D model for finite element analysis can be determined. Development of the modeling method and an example case are presented.

Handschuh, Robert F.↗
NASA NTRS1991

The detection of the electric field vertical distribution underneath thundercloud: Principle and applications

During the Florida 89 experiment at Kennedy Space Center, a new system was used in order to obtain the vertical distribution of the electric field underneath thunderstorms. It consists of a standard shutter field mill at ground level and five other field sensors suspended from a cable fastened to a tethered balloon located at an altitude of about 1000 meters. It also includes a reception station for telemetered information transmitted by sensors, a processing system in order to store data, and real time display on a screen to show the simultaneous field variations at each level along with the instantaneous electric field profile. The first results obtained show the great importance of the electric field vertical distribution. The field detected at a height of 600m reaches 65 kV/m while that at the surface does not exceed 5 kV/m. The field intensity in altitude is a better criterion for determining the right moment to launch a rocket devoted to flash triggering. Using Gauss's law, the simultaneous field variations at several levels are used in order to evaluate charge densities. Average values close to 1nC.m(-3) are calculated in layers up to 600 m. The calculation of different average charge densities leads to the characterization of the layer between cloud and ground just before the leader propagation in the case of cloud to ground flash.

Soula, Serge↗
NASA NTRS1991

The spatial variations of lightning during small Florida thunderstorms

Networks of field mills (FM's) and lightning direction finders (LDF's) were used to locate lightning over the NASA KSC on three storm days. Over 90 percent of all cloud-to-ground (CG) flashes that were detected by the LDF's in the study area were also detected by the LDF's. About 17 percent of the FM CG events could be fitted to either a monopole or a dipole charge model. These projected FM charge locations are compared to LDF locations, i.e., the ground strike points. It was found that 95 percent of the LDF points are within 12 km of the FM charge, 75 percent are within 8 km, and 50 percent are within 4 km. For a storm on 22 Jul. 1988, there was a systematic 5.6 km shift between the FM charge centers and the LDF strike points that might have been caused by the meteorological structure of the storm.

Oram, Timothy D.↗
NASA NTRS1991

The use of Doppler radar to help forecast the development of thunderstorms

The role of Doppler radars in forecasting the location and timing of the initiation of thunderstorms both over Kennedy Space Center and central Florida is analyzed. The data used in this analysis was collected with two Doppler radars with high temporal and spatial resolution throughout the troposphere. Previous studies of thunderstorm initiation in the vicinity of Kennedy Space Center, including synoptic and site-specific observations are outlined. As a result of the analysis of nine cases of thunderstorm initiation, it is concluded that an expert system could be developed that would take input data from the existing field mill network, instrumented tower network, lightning detection system, from sounding, and from Doppler-radar-based algorithms. Such a system would be able to determine a probability of thunderstorm development in the next 10, 20, and 30 minutes for the area of interest.

Eilts, Michael D.↗
NASA NTRS1991

YBa2Cu3O(7-x)/Au/Nb device structures

Fabrication and testing of planar and edge geometry YBaCuO/Au/Nb superconductor/normal-metal/superconductor (SNS) device structures is described. Weak-link devices of this type serve as sensitive probes of the electrical quality of the YBaCuO/Au interface. The devices are fabricated using laser-ablated, in situ, c-axis-oriented YBaCuO thin films, with both annealed and unannealed YBaCuO/Au interfaces. The planar SNS structures are formed by sequential, in situ deposition of YBaCuO, Au, and Nb, followed by etching, planarization, and wiring electrode definition to produce junctions ranging from 5 to 20 micron on a side. Resulting RnA products are 1-10 x 10 to the -8th ohm-sq cm with critical current densities up to 5 kA/sq cm. For the edge geometry devices, the YBaCuO film edges are patterned using Ar ion milling, followed by a low energy ion cleaning step and in situ deposition of Au and Nb. Devices with areas in the 10 to the -7th to 10 to the -8th sq cm range have been fabricated with RnA products lower than 10 to the -8th ohm-sq cm and critical current densities up to 3kA/sq cm. Both types of devices show ac Josephson steps under microwave irradiation. The best results have been obtained with annealed YBaCuO/Au interfaces.

Hunt, B. D.↗
NASA NTRS1992

Simple Method For Detection Of Intergranular Attack

Evidence of intergranular attack occurring on chemically milled and wire-electrical-discharge-machined metal parts detected with replicating tape which makes it unnecessary to manufacture and stock test coupons and inspect them microscopically. Tape pressed on part to be inspected. When removed, it presents visual evidence of intergranular attack.

Jackson, Amy A.↗
NASA NTRS1992

Speed-Selector Guard For Machine Tool

Simple guardplate prevents accidental reversal of direction of rotation or sudden change of speed of lathe, milling machine, or other machine tool. Custom-made for specific machine and control settings. Allows control lever to be placed at only one setting. Operator uses handle to slide guard to engage or disengage control lever. Protects personnel from injury and equipment from damage occurring if speed- or direction-control lever inadvertently placed in wrong position.

Shakhshir, Roda J.↗
NASA NTRS1991

A method for determining spiral-bevel gear tooth geometry for finite element analysis

An analytical method was developed to determine gear tooth surface coordinates of face-milled spiral bevel gears. The method uses the basic gear design parameters in conjunction with the kinematical aspects of spiral bevel gear manufacturing machinery. A computer program, SURFACE, was developed. The computer program calculates the surface coordinates and outputs 3-D model data that can be used for finite element analysis. Development of the modeling method and an example case are presented. This analysis method could also find application for gear inspection and near-net-shape gear forging die design.

Handschuh, Robert F.↗
NASA NTRS1992

Toughened uni-piece fibrous insulation

A porous body of fibrous, low density silica-based insulation material is at least in part impregnated with a reactive boron oxide containing borosilicate glass frit, a silicon tetraboride fluxing agent and a molybdenum silicide emittance agent. The glass frit, fluxing agent and emittance agent are separately milled to reduce their particle size, then mixed together to produce a slurry in ethanol. The slurry is then applied to the insulation material and sintered to produce the porous body.

Leiser, Daniel B↗
NASA NTRS1991

CRN5EXP: Expert system for statistical quality control

The purpose of the Expert System CRN5EXP is to assist in checking the quality of the coils at two very important mills: Hot Rolling and Cold Rolling in a steel plant. The system interprets the statistical quality control charts, diagnoses and predicts the quality of the steel. Measurements of process control variables are recorded in a database and sample statistics such as the mean and the range are computed and plotted on a control chart. The chart is analyzed through patterns using the C Language Integrated Production System (CLIPS) and a forward chaining technique to reach a conclusion about the causes of defects and to take management measures for the improvement of the quality control techniques. The Expert System combines the certainty factors associated with the process control variables to predict the quality of the steel. The paper presents the approach to extract data from the database, the reason to combine certainty factors, the architecture and the use of the Expert System. However, the interpretation of control charts patterns requires the human expert's knowledge and lends to Expert Systems rules.

Hentea, Mariana↗
NASA NTRS1991

Algorithms for contours depicting static electric fields during adverse weather conditions

A flexible and functional analytical tool is developed for the study of electric fields during adverse weather conditions. This tool is designed for use by members of the Atmospheric Science Group as part of their overall effort to appraise environmental conditions during these situations. It is also used to illustrate approaches open to those interested in the study of the physics of ambient electric field phenomena. Computer resources of KSC are coordinated with original software to produce contour interpretations of electric field data available from a grid of field mills spanning the region. Three model algorithms are presented and examples are given illustrating the system design, flexibility, and utility.

Rompala, John T.↗
NASA NTRS1991

Ultra-precision processes for optics manufacturing

The Optics MODIL (Manufacturing Operations Development and Integration Laboratory) is developing advanced manufacturing technologies for fabrication of ultra precision optical components, aiming for a ten-fold improvement in precision and a shortening of the scheduled lead time. Current work focuses on diamond single point turning, ductile grinding, ion milling, and in/on process metrology.

Martin, William R.↗
NASA NTRS1992

Tubular copper thrust chamber design study

The use of copper tubular thrust chambers is particularly important in high performance expander cycle space engines. Tubular chambers have more surface area than flat wall chambers, and this extra surface area provides enhanced heat transfer for additional energy to power the cycle. This paper was divided into two sections: (1) a thermal analysis and sensitivity study; and (2) a preliminary design of a selected thrust chamber configuration. The thermal analysis consisted of a statistical optimization to determine the optimum tube geometry, tube booking, thrust chamber geometry, and cooling routing to achieve the maximum upper limit chamber pressure for a 25,000 pound thrust engine. The preliminary design effort produced a layout drawing of a tubular thrust chamber that is three inches shorter than the Advanced Expander Test Bed (AETB) milled channel chamber but is predicted to provide a five percent increase in heat transfer. Testing this chamber in the AETB would confirm the inherent advantages of tubular chamber construction and heat transfer.

Masters, A. I.↗
NASA NTRS1992

Control concepts for active magnetic bearings

Active Magnetic Bearings (AMB) are becoming increasingly significant for various industrial applications. Examples are turbo-compressors, centrifuges, high speed milling and grinding spindles, vibration isolation, linear guides, magnetically levitated trains, vacuum and space applications. Thanks to the rapid progress and drastic cost reduction in power- and micro-electronics, the number of AMB applications is growing very rapidly. Industrial uses of AMBs leads to new requirements for AMB-actuators, sensor systems, and rotor dynamics. Especially desirable are new and better control concepts to meet demand such as low cost AMB, high stiffness, high performance, high robustness, high damping up to several kHz, vibration isolation, force-free rotation, and unbalance cancellation. This paper surveys various control concepts for AMBs and discusses their advantages and disadvantages. Theoretical and experimental results are presented.

Siegwart, Roland↗
NASA NTRS1981

Gravitropism in higher plant shoots. I - A role for ethylene

Two inhibitors of ethylene synthesis, Co(2+) and aminoethoxyvinylglycine (AVG), and two inhibitors of ethylene action, Ag(+) and CO2, are shown to delay the gravitropic response of cocklebur (Xanthium strumarium L.), tomato (Lycopersicon esculentum Mill.), and castor bean (Ricinus communis L.) stems. Gentle shaking on a mechanical shaker does not inhibit the gravitropic response, but vigorous hand shaking for 120 seconds delays the response somewhat. AVG and Ag(+) further delay the response of mechanically stimulated plants. AVG retards the storage of bending energy but not of stimulus. In gravitropism, graviperception may first stimulate ethylene evolution, which may then influence bending directly, or responses involving ethylene could be more indirect.

Wheeler, Raymond M.↗