Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “PROCESS CONTROL”

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.

At least 1,603 records · Page 89
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

The meteorological measurement system on the NASA ER-2 aircraft

A Meteorological Measurement System (MMS) was designed for the high-altitude ER-2 aircraft (NASA 706). Through dedicated instrumentation installed on the aircraft and repeated calibrations, the MMS provides accurate in situ measurements of free-stream pressure, temperature, and the wind vector. The MMS has participated in two major high-altitude scientific expeditions, the Stratosphere-Troposphere Exchange Project (STEP) based in northern Australia and the Airborne Antarctic Ozone Experiment (AAOE) based in southern Chile. Key MMS subsystems are described. The MMS consists of a dedicated inertial navigation system (INS), a randome differential pressure system, a data acquisition system, and air data instrumentation. The MMS incorporates a high-resolution INS (Litton LIN-72RH model), which is specially configured and is updated at 25 Hz. The differential pressure system, consisting of two sets of pressure ports and transducers, is installed in the ER-2 radome to provide sensitive measurements of the airflow angles (angle of attack and angle of sideslip). The data acquisition system was designed to meet aircraft requirements of compactness and light weight (2 cu ft 50 lb) and for MMS requirements to sample, control, process, and store 45 parameters (some redundant) at a sampling rate up to 10 Hz. The MMS data are stored both in a tape recorder (20 MB) and a hermatically-sealed winchester hard disc (10 MB). Special and redundant instrumentation for temperature and pressure measurements were also installed on the aircraft.

Scott, Stan G.↗
NASA NTRS1988

An expert system for satellite and instrument data anomaly and fault isolation

A prototype Generic Payload Operations Control System (GPOCC) is being developed at the NASA Jet Propulsion Laboratory to provide a low-cost command and control processing center for science instruments and small payloads. The GPOCC supports the difficult transition from integration and test to flight operations. The prototype will incorporate four expert systems to perform telemetry, command, and mission planning functions as well as telecommunications scheduling. The first of these expert systems to be developed will perform telemetry data analysis and fault isolation, as well as propose corrective action. This Data Analysis Module (DAM) will monitor telemetry data and perform continual data monitoring and trend analysis based on a knowledge base and historic data archived on an optical disk storage device. The system maintains a continuous knowledge database of past system performance characteristics. The goal of the Data Analysis Module is to achieve consistent, dependable and validatable performance, to demonstrate thorough, reliable and fast reasoning, and to reduce the concentration demanded of flight analysis personnel.

Busse, Carl↗
NASA NTRS1986

The CAIS 2 Project

The Common APSE Interface Set (CAIS) is a proposed MIL-STD intended to promote the portability of Ada Programming Support Environment (APSE) tools written in Ada. The standardized interfaces define a virtual operating system, from which portable tools derive their basic services, e.g., file management, input/output, communications, and process control. In the Ada world, such a virtual operating system is called a Kernel Ada Programming Support Environment (KAPSE). The CAIS is a standardized interface between KAPSEs and tools. The CAIS has been proposed as a starting point for standard interfaces to be used in the NASA Software Support Environment (SSE) for the Space Station Program. The status of the CAIS standardization effort and plans for further development are described.

Legrand, Sue↗
NASA NTRS1988

Data systems

The Data Systems Program consists of research and technology devoted to controlling, processing, storing, manipulating, and analyzing space-derived data. The objectives are to provide the technology advancements needed to enable affordable utilization of space-derived data, to increase substantially the capability for future missions of on-board processing and recording and to provide high speed and high volume computational systems anticipated for missions such as the evolutionary Space Station and Earth Observing System. The Data Systems Program supports fundamental research in such areas as laser diodes, supports work to select and provide the appropriate on-board processor technology for future NASA missions, and also supports the development of two flight processors with special architectures.

Smith, Paul H.↗
NASA NTRS1989

Applications of fuzzy sets to rule-based expert system development

Problems of implementing rule-based expert systems using fuzzy sets are considered. A fuzzy logic software development shell is used that allows inclusion of both crisp and fuzzy rules in decision making and process control problems. Results are given that compare this type of expert system to a human expert in some specific applications. Advantages and disadvantages of such systems are discussed.

Lea, Robert N.↗
NASA NTRS1988

Cooperating expert systems for Space Station - Power/thermal subsystem testbeds

The Systems Autonomy Demonstration Project (SADP) is a NASA-sponsored series of increasingly complex demonstrations to show the benefits of integrating knowledge-based systems with conventional process control in real-time, real-world problem domains that can facilitate the operations and availability of major Space Station distributed systems. This paper describes the system design, objectives, approaches, and status of each of the testbed knowledge-based systems. Simplified schematics of the systems are shown.

Wong, Carla M.↗
NASA NTRS1989

Bars within bars - A mechanism for fuelling active galactic nuclei

A mechanism, applicable to AGN and nuclear starburst galaxies in which there is accretion onto a supermassive black hole (SBH), is proposed which brings in gas from large to small scales by successive dynamical instabilities. On the large scale, a stellar bar sweeps the interstellar medium into a gaseous disk a few hundred pc in radius. Under certain conditions, this disk can become unstable again, allowing material to flow inwards until turbulent viscous processes control angular-momentum transport. This flow pattern may feed viscosity-driven accretion flows around an SBH or lead to the formation of an SBH if none was present initially.

Shlosman, Isaac↗
NASA NTRS1989

Acoustic temperature profile measurement technique for large combustion chambers

Measurement of times of flight of sound waves can be used to determine temperatures in a gas. This paper describes a system, based on this principle, that is capable of giving the temperature profile in a nonisothermal gas volume, for example, prevalent in a large furnace. The apparatus is simple, rugged, accurate, and capable of being automated for process control applications. It is basically an acoustic waveguide where the outside temperature profile is transferred to a chosen gas contained inside the guide.

Venkateshan, S. P.↗
NASA NTRS1990

Markov Chains For Testing Redundant Software

Preliminary design developed for validation experiment that addresses problems unique to assuring extremely high quality of multiple-version programs in process-control software. Approach takes into account inertia of controlled system in sense it takes more than one failure of control program to cause controlled system to fail. Verification procedure consists of two steps: experimentation (numerical simulation) and computation, with Markov model for each step.

White, Allan L.↗
NASA NTRS1990

Master/Programmable-Slave Computer

Unique modular computer features compactness, low power, mass storage of data, multiprocessing, and choice of various input/output modes. Master processor communicates with user via usual keyboard and video display terminal. Coordinates operations of as many as 24 slave processors, each dedicated to different experiment. Each slave circuit card includes slave microprocessor and assortment of input/output circuits for communication with external equipment, with master processor, and with other slave processors. Adaptable to industrial process control with selectable degrees of automatic control, automatic and/or manual monitoring, and manual intervention.

Smaistrla, David↗
NASA NTRS1990

Experiments and other methods for developing expertise with design of experiments in a classroom setting

The only way to gain genuine expertise in Statistical Process Control (SPC) and the design of experiments (DOX) is with repeated practice, but not on canned problems with dead data sets. Rather, one must negotiate a wide variety of problems each with its own peculiarities and its own constantly changing data. The problems should not be of the type for which there is a single, well-defined answer that can be looked up in a fraternity file or in some text. The problems should match as closely as possible the open-ended types for which there is always an abundance of uncertainty. These are the only kinds that arise in real research, whether that be basic research in academe or engineering research in industry. To gain this kind of experience, either as a professional consultant or as an industrial employee, takes years. Vast amounts of money, not to mention careers, must be put at risk. The purpose here is to outline some realistic simulation-type lab exercises that are so simple and inexpensive to run that the students can repeat them as often as desired at virtually no cost. Simulations also allow the instructor to design problems whose outcomes are as noisy as desired but still predictable within limits. Also the instructor and the students can learn a great deal more from the postmortum conducted after the exercise is completed. One never knows for sure what the true data should have been when dealing only with real life experiments. To add a bit more realism to the exercises, it is sometimes desirable to make the students pay for each experimental result from a make-believe budget allocation for the problem.

Patterson, John W.↗
NASA NTRS1989

Apparent activation volume for creep of copper and alpha brass at intermediate temperatures

Experimental measurements of the apparent activation volume for creep, V-asterisk, of Cu and Cu-30 pct Zn conducted at intermediate temperatures showed two types of strain dependencies. At the lower temperatures and higher stresses, V-asterisk decreased with increasing creep strain, while at higher temperatures and lower stresses, V-asterisk was essentially independent of strain. The low temperature-high stress behavior for Cu and Cu-30 pct Zn was found to be consistent with the dominance of a dislocation intersection mechanism. The high temperature-low stress data for the pure metals suggest that the rate-controlling process involves the nonconservative motion of jogs on screw dislocations. For the latter conditions, an additional contribution from solute drag-limited dislocation glide also appears to be important in governing the creep behavior of the alloy.

Raj, S. V.↗
NASA NTRS1989

Simple autonomous Mars walker

Under a contract with NASA's Jet Propulsion Laboratory, Martin Marietta has developed several alternative rover concepts for unmanned exploration of the planet Mars. One of those concepts, the 'Walking Beam', is the subject of this paper. This concept was developed with the goal of achieving many of the capabilities of more sophisticated articulated-leg walkers with a much simpler, more robust, less computationally demanding and more power efficient design. It consists of two large-base tripods nested one within the other which alternately translate with respect to each other along a 5-meter beam to propel the vehicle. The semiautonomous navigation system relies on terrain geometry sensors and tacticle feedback from each foot to autonomously select a path which avoids hazards along a route designated from earth. Both mobility and navigation features of this concept are discussed including a top-level description of the vehicle's physical characteristics, deployment strategy, mobility elements, sensor suite, theory of operation, navigation and control processes, and estimated performance.

Larimer, Stanley J.↗
NASA NTRS1989

A 'figure-of-merit' approach to extraterrestrial resource utilization

An approach for interrelated optimizations in space missions that utilize extraterrestrial resources is developed, consisting in the concept of an overall mission 'figure-of-merit' leading to more realistic designs than through individual performance maximizations. After a brief discussion of this concept, the synthesis of four major components of any future space mission is considered. The four major components are: orbital mechanics of the transportation; performance of the rocket motors; support systems including power, thermal and process controls, and instruments; and in situ resource utilization plant equipment. The Mars Sample Return mission is the basis of an illustration of the proposed concept. A popular spreadsheet is used to quantitatively demonstrate the interdependent nature of the mission optimization. Future prospects are outlined, that promise great economy through extraterrestrial resource utilization and a quick evaluation technique.

Ramohalli, Kumar↗
NASA NTRS1989

Applications of fuzzy sets to rule-based expert system development

Problems of implementing rule-based expert systems using fuzzy sets are considered. A fuzzy logic software development shell is used that allows inclusion of both crisp and fuzzy rules indecision making and process control problems. Results are given that compare this type of expert system to a human expert in some specific applications. Advantages and disadvantages of such systems are discussed.

Lea, Robert N.↗
NASA NTRS1989

NASA aerospace battery systems program update

An overview of a battery systems program designed to enhance the safety, reliability, and performance of NASA's aerospace primary and secondary batteries as well as battery power systems is presented. The status of research in all three areas is reviewed. The approach to achieving the program objectives involves increasing the fundamental understanding of primary and secondary cells; providing for improved nickel-cadmium manufacturing process control; providing for the establishment of a NASA standard nickel-hydrogen cell design; establishing specifications, design and operational guidelines for both primary and secondary cells and batteries; providing training relating to the above areas; and opening and maintaining communication lines within NASA and the aerospace battery community.

Manzo, Michelle A.↗
NASA NTRS1990

Fixed-head star tracker magnitude calibration on the solar maximum mission

The sensitivity of the fixed-head star trackers (FHSTs) on the Solar Maximum Mission (SMM) is defined as the accuracy of the electronic response to the magnitude of a star in the sensor field-of-view, which is measured as intensity in volts. To identify stars during attitude determination and control processes, a transformation equation is required to convert from star intensity in volts to units of magnitude and vice versa. To maintain high accuracy standards, this transformation is calibrated frequently. A sensitivity index is defined as the observed intensity in volts divided by the predicted intensity in volts; thus, the sensitivity index is a measure of the accuracy of the calibration. Using the sensitivity index, analysis is presented that compares the strengths and weaknesses of two possible transformation equations. The effect on the transformation equations of variables, such as position in the sensor field-of-view, star color, and star magnitude, is investigated. In addition, results are given that evaluate the aging process of each sensor. The results in this work can be used by future missions as an aid to employing data from star cameras as effectively as possible.

Pitone, Daniel S.↗
NASA NTRS1990

Masking failures of multidimensional sensors (extended abstract)

When a computer monitors a physical process, the computer uses sensors to determine the values of the physical variables that represent the state of the process. A sensor can sometimes fail, however, and in the worst case report a value completely unrelated to the true physical value. The work described is motivated by a methodology for transforming a process control program that can not tolerate sensor failure into one that can. In this methodology, a reliable abstract sensor is created by combining information from several real sensors that measure the same physical value. To be useful, an abstract sensor must deliver reasonably accurate information at reasonable computational cost. Sensors are considered that deliver multidimensional values (e.g., location or velocity in three dimensions, or both temperature and pressure). Geometric techniques are used to derive upper bounds on abstract sensor accuracy and to develop efficient algorithms for implementing abstract sensors.

Chew, Paul↗