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At least 739 records · Page 41

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DOE OSTI2024

Neural Networks for Prediction of Complex Chemistry in Water Treatment Process Optimization

Water chemistry plays a critical role in the design and operation of water treatment processes. Detailed chemistry modeling tools use a combination of advanced thermodynamic models and extensive databases to predict phase equilibria and reaction phenomena. The complexity and formulation of these models preclude their direct integration in equation-oriented modeling platforms, making it difficult to use their capabilities for rigorous water treatment process optimization. Neural networks (NN) can provide a pathway for integrating the predictive capability of chemistry software into equation-oriented models and enable optimization of complex water treatment processes across a broad range of conditions and process designs. Herein, we assess how NN architecture and training data impact their accuracy and use in equation-oriented water treatment models. We generate training data using PhreeqC software and determine how data generation and sample size impact the accuracy of trained NNs. The effect of NN architecture on optimization is evaluated by optimizing hypothetical black-box desalination processes using a range of feed compositions from USGS brackish water data set, tracking the number of successful optimizations, and testing the impact of initial guess on the final solution. Our results clearly demonstrate that data generation and architecture impact NN accuracy and viability for use in equation-oriented optimization problems.

Dudchenko, Alexander V↗

NASA NTRS1972

Batch fabrication process development for ferrite logic conductors

A process for fabricating ultrareliable magnetic ferrite logic circuits is described in which the conductors are formed by a combination of two batch type processes - photolithography and electroplating - and a mechanized writing process for completing conductors in the third dimension. Up to 4 turns, through an aperture 1 mm in diameter, are formed by the described process. The number of joints in the conductors is reduced by use of this process to only those which are required for input, output and power connections of a logic block. To demonstrate feasibility, 8-stage magnetic ring counter circuits have been fabricated.

Heckler, C. H., Jr.↗

NASA NTRS1972

Data processing at the University of Kansas

Two systems for processing remotely sensed image data have been discussed. The first system, IDECS, is a near real-time hardware system oriented towards processing multi-image data sets quickly and economically. The IDECS has convenient film input and color display output capabilities and implements simple kinds of decision rules. The second system, KANDIDATS, is a software system capable of performing many of the more sophisticated processing methods. Because of its monitor which handles all bookkeeping and its modular design, KANDIDATS easily allows the testing of new automatic processing techniques. After a new technique has been proven on KANDIDATS, it may be simplified and hard-wired in IDECS, thereby keeping the volume processing of remotely sensed data always up to the current state-of-the-art.

Haralick, R. M.↗

NASA NTRS1972

Rapid processing of multispectral scanner data using linear techniques.

Tests have been made to compare linear and quadratic techniques for processing multispectral scanner data. The tests have been limited to a few selected sets of agricultural data. Two aspects of processing were studied. The first, the selection of a subset of channels to be used in the decision function, was found to be faster by a factor of 50 when a linear method was used. Second, in recognition processing, our linear decision rule produced a lower error rate and utilized a larger number of channels for equal processing times. Nevertheless, when the criterion is lowest possible error rate, irregardless of processing time, the quadratic rule is preferable.

Crane, R. B.↗

NASA NTRS1974

Space processing applications payload equipment study. Volume 2A: Experiment requirements

An analysis of the space processing applications payload equipment was conducted. The primary objective was to perform a review and an update of the space processing activity research equipment requirements and specifications that were derived in the first study. The analysis is based on the six major experimental classes of: (1) biological applications, (2) chemical processes in fluids, (3) crystal growth, (4) glass technology, (5) metallurgical processes, and (6) physical processes in fluids. Tables of data are prepared to show the functional requirements for the areas of investigation.

Smith, A. G.↗

NASA NTRS1973

An improved numerical process for solution of solid mechanics problems

This paper gives an overview of the development and status of an improved numerical process for the solution of solid mechanics problems. The proposed process uses a mixed formulation with the fundamental unknowns consisting of both stress and displacement parameters. The problem is formulated either by means of first-order partial differential equations or in a variational form by using a Hellinger-Reissner-type mixed variational principle. For presentation purposes, the components of a numerical process are characterized and the criteria for an ideal process are outlined. Commonly used finite-difference and finite-element procedures are examined in the light of these criteria and it is shown that they fall short in a number of ways. The proposed numerical process, on the other hand, satisfies most of the optimality criteria and appears to be particularly suited for use with the forthcoming generation computers.

Noor, A. K.↗

NASA NTRS1974

Preparation and metallurgical properties of low gravity processed immiscible materials

Initial experiments conducted during the Apollo 14 mission demonstrated that unique dispersions of immiscible materials could be obtained by processing in a low gravity environment. Subsequently, seven metallic systems have been processed in three NASA facilities: the drop tower at MSFC, the M-512 facility on board a KC-135 aircraft and the M-518 furnace on board Skylab. All couples were solidified from the liquid while in a low gravity environment, with one gravity processed specimens as controls. Metallographic examination demonstrated that the specimens processed in a low gravity environment exhibited a more uniform dispersion and microstructure than the one gravity processed controls.

Reger, J. L.↗

NASA NTRS1974

ERTS operations and data processing

The overall communications and data flow between the ERTS spacecraft and the ground stations and processing centers are generally described. Data from the multispectral scanner and the return beam vidicon are telemetered to a primary ground station where they are demodulated, processed, and recorded. The tapes are then transferred to the NASA Data Processing Facility (NDPF) at Goddard. Housekeeping data are relayed from the prime ground stations to the Operations Control Center at Goddard. Tracking data are processed at the ground stations, and the calculated parameters are transmitted by teletype to the orbit determination group at Goddard. The ERTS orbit has been designed so that the same swaths of the ground coverage pattern viewed during one 18-day coverage cycle are repeated by the swaths viewed on all subsequent cycles. The Operations Control Center is the focal point for all communications with the spacecraft. NDPF is a job-oriented facility which processes and stores all sensor data, and which disseminates large quantities of these data to users in the form of films, computer-compatible tapes, and data collection system data.

Gonzales, L.↗

NASA NTRS1973

An empirical analysis of the distribution of overshoots in a stationary Gaussian stochastic process

The frequency distribution of overshoots in a stationary Gaussian stochastic process is analyzed. The primary processes involved in this analysis are computer simulation and statistical estimation. Computer simulation is used to simulate stationary Gaussian stochastic processes that have selected autocorrelation functions. An analysis of the simulation results reveals a frequency distribution for overshoots with a functional dependence on the mean and variance of the process. Statistical estimation is then used to estimate the mean and variance of a process. It is shown that for an autocorrelation function, the mean and the variance for the number of overshoots, a frequency distribution for overshoots can be estimated.

Carter, M. C.↗

NASA NTRS1974

Film processing in scientific spacecraft television systems

Photography and photochemical processing of the film in spacecraft phototelevision systems involve several aspects which require an approach to selection of the handling process which differs from that used under ground conditions, different processing technology, and different construction of the instrument for carrying out the processing. Soviet processing techniques and equipment are described.

Aleshin, G. M.↗

NASA NTRS1975

Space processing of composite materials

Materials and processes for the testing of aluminum-base fiber and particle composites, and of metal foams under extended-time low-g conditions were investigated. A wetting and dispersion technique was developed, based on the theory that under the absence of a gas phase all solids are wetted by liquids. The process is characterized by a high vacuum environment and a high temperature cycle. Successful wetting and dispersion experiments were carried out with sapphire fibers, whiskers and particles, and with fibers of silicon carbide, pyrolytic graphite and tungsten. The developed process and facilities permit the preparation of a precomposite which serves as sample material for flight experiments. Low-g processing consists then merely in the uniform redistribution of the reinforcements during a melting cycle. For the preparation of metal foams, gas generation by means of a thermally decomposing compound was found most adaptable to flight experiments. For flight experiments, the use of compacted mixture of the component materials limits low-g processing to a simple melt cycle.

Steurer, W. H.↗

NASA NTRS1975

Space Processing Applications - The new challenge

The impact of Skylab Space Processing Applications experiments upon ground based research laboratory capabilities is discussed. The findings of a few selected space processing Skylab experiments are summarized and explained. The objectives of the ASTP space processing experiments are summarized. NASA's plans for use of sounding rockets for space processing experiments are outlined briefly. The integration of NASA's Space Processing Program into an active planning effort for use of Shuttle is reviewed.

Montgomery, B. O.↗

NASA NTRS1975

Thermochemical production of hydrogen via multistage water splitting processes

This paper presents and reviews the fundamental thermodynamic principles underlying thermochemical water splitting processes. The overall system is considered first and the temperature limitation in process thermal efficiency is developed. The relationship to an ideal water electrolysis cell is described and the nature of efficient multistage reaction processes is discussed. The importance of the reaction entropy change and the relation of the reaction free energy change to the work of separation is described. A procedure for analyzing thermochemical water splitting processes is presented and its use to calculate individual stage efficiency is demonstrated. A number of processes are used to illustrate the concepts and procedures.

Funk, J. E.↗

NASA NTRS1975

Low cost processes for solar-grade silicon

Upgrading metallurgical grade silicon is being pursued in four associated areas in order to improve the purity of the normally 98% material. The first two work areas involve purification of raw materials entering the process in addition to upgrading the arc furnace itself. The second two areas of process upgrading comprise improving the purity of the silicon after it leaves the arc furnace by reactive gas blowing and unidirectional freezing. The best cell produced to date was fabricated from MG-Si that had been blown with an O2-Cl2 mixture, unidirectionally solidified, and 6-float-zone passed (to determine a base boron level of 0.04 ohm/cm). The cell showed a 10.7% AMO efficiency. In the other processes category, the use of silicates as a silicon source and of electrolysis as a process were studied. The best electrolytic process uses a 1000 C fused salt of silica in cryolite.

Hunt, L. P.↗

NASA NTRS1975

Stochastic process approximation for recursive estimation with guaranteed bound on the error covariance

An approach, is proposed for the design of approximate, fixed order, discrete time realizations of stochastic processes from the output covariance over a finite time interval, was proposed. No restrictive assumptions are imposed on the process; it can be nonstationary and lead to a high dimension realization. Classes of fixed order models are defined, having the joint covariance matrix of the combined vector of the outputs in the interval of definition greater or equal than the process covariance; (the difference matrix is nonnegative definite). The design is achieved by minimizing, in one of those classes, a measure of the approximation between the model and the process evaluated by the trace of the difference of the respective covariance matrices. Models belonging to these classes have the notable property that, under the same measurement system and estimator structure, the output estimation error covariance matrix computed on the model is an upper bound of the corresponding covariance on the real process. An application of the approach is illustrated by the modeling of random meteorological wind profiles from the statistical analysis of historical data.

Menga, G.↗

NASA NTRS1976

Space processing of chalcogenide glass

The manner in which the weightless, containerless nature of in-space processing can be successfully utilized to improve the quality of infrared transmitting chalcogenide glasses was investigated. The following conclusions were reached: (1) Laboratory experiments have established the techniques, processes and equipment necessary for the production of high purity chalcogenide glasses. (2) Processing techniques have been successfully adopted for Ge28Sb12Se60 glass in a 1-g environment. (3) The Ge28Sb12Se60 glasses that have been processed have optical transmission around 63% (5 mm thick). (4) Laboratory experiments have established that the use of precursor materials in powdered form increases the oxygen contamination of the processed glass. This indicates that high purity precursor materials in bar or pellet form should be used. (5) Modifications were made on the MSFC acoustic levitator in an attempt to improve levitation stability during long-time experiments. Room temperature experiments on As2S3 glasses and high temperature experiments on polystyrene were conducted.

Ali, M. A.↗

NASA NTRS1977

Data processing system and interfacing elements time base analysis

The processing of time in the Orbiter System Services software and the associated facilities provided to the user community are described. The descriptions are directed toward showing the functional intent of the design rather than the actual implementation. Simplified flow diagrams are included. Based upon detailed analysis of a preliminary review copy of the Approach and Landing Test (ALT) System Software Detailed Design Specification and the Program Listings for Version 17 Prime, the processing of time has the potential for error free operations. The processing of time is not expected to change between ALT and the Operational Flight Test (OFT) other than differences in value of some constants for control and limit checking. Due to the dynamic nature of onboard time processing and its criticality to the successful operation of the orbiter, it is recommended that a comprehensive list of external variables, their locations, initial values, and a 'where used' listing be produced, as a by-product of the link edit process, for all non-HAL coding. In addition, a careful review of the verification test procedures for the System Services time-related software is recommended.

Blackburn, J. D.↗

NASA NTRS1977

Cost analysis of advanced turbine blade manufacturing processes

A rigorous analysis was conducted to estimate relative manufacturing costs for high technology gas turbine blades prepared by three candidate materials process systems. The manufacturing costs for the same turbine blade configuration of directionally solidified eutectic alloy, an oxide dispersion strengthened superalloy, and a fiber reinforced superalloy were compared on a relative basis to the costs of the same blade currently in production utilizing the directional solidification process. An analytical process cost model was developed to quantitatively perform the cost comparisons. The impact of individual process yield factors on costs was also assessed as well as effects of process parameters, raw materials, labor rates and consumable items.

Barth, C. F.↗