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At least 613 records · Page 34
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Situation management in the Link Monitor and Control Operator Assistant (LMCOA)

This paper describes a knowledge-based system called the Situation Manager that was developed for the Link Monitor and Control Operator Assistant (LMCOA) at the Jet Propulsion Laboratory. This system was developed in response to a number of deficiencies that were identified in an earlier version of the LMCOA: the need to close the control loop between sending a directive and knowing when its execution is complete (versus just closing the communications loop), the need to recognize an anomaly and alert the operator when a directive is rejected or a link device fails, and the need to suggest ways to work around an anomaly, provided that it is recognizable. In response to these needs, the Situation Manager has been designed to provide the LMCOA with three basic capabilities: situation assessment, anomaly diagnosis, and recovery from commonly occurring problems.

Hill, Randall W., Jr.↗
NASA NTRS1993

A model-based approach for detection of objects in low resolution passive-millimeter wave images

We describe a model-based vision system to assist pilots in landing maneuvers under restricted visibility conditions. The system was designed to analyze image sequences obtained from a Passive Millimeter Wave (PMMW) imaging system mounted on the aircraft to delineate runways/taxiways, buildings, and other objects on or near runways. PMMW sensors have good response in a foggy atmosphere; but, their spatial resolution is very low. However, additional data such as airport model and approximate position and orientation of aircraft are available. We exploit these data to guide our model-based system to locate objects in the low resolution image and generate warning signals to alert the pilots. We also derive analytical expressions for the accuracy of the camera position estimate obtained by detecting the position of known objects in the image.

Tang, Yuan-Liang↗
NASA NTRS1994

An investigation of air transportation technology at the Massachusetts Institute of Technology, 1992-1993

An investigation of air transportation technology at MIT during 1992 - 1993 is presented. One completed project and two continuing research activities are under the sponsorship of the FAA/NASA Joint University Program. The completed project was on tracking aircraft around a turn with wind effects. Active research projects are on ASLOTS - an interactive adaptive system of automated approach spacing of aircraft and alerting in automated and datalink capable cockpits.

Simpson, Robert W.↗
NASA NTRS1994

A data fusion algorithm for multi-sensor microburst hazard assessment

A recursive model-based data fusion algorithm for multi-sensor microburst hazard assessment is described. An analytical microburst model is used to approximate the actual windfield, and a set of 'best' model parameters are estimated from measured winds. The winds corresponding to the best parameter set can then be used to compute alerting factors such as microburst position, extent, and intensity. The estimation algorithm is based on an iterated extended Kalman filter which uses the microburst model parameters as state variables. Microburst state dynamic and process noise parameters are chosen based on measured microburst statistics. The estimation method is applied to data from a time-varying computational simulation of a historical microburst event to demonstrate its capabilities and limitations. Selection of filter parameters and initial conditions is discussed. Computational requirements and datalink bandwidth considerations are also addressed.

Wanke, Craig R.↗
NASA NTRS1994

MSFC inspections of installed polyimide wire

An alert was issued because of the arc-tracking possibilities of installed polyimide wire harnesses. MSFC undertook a program to try to enhance the safety and reliability of these harnesses. Photographs are presented showing the need for inspections of installed wiring harnesses.

Landers, Joe C.↗
NASA NTRS1994

Implementing bright light treatment for MSFC payload operations shiftworkers

Intense light can phase-shift circadian rhythms and improve performance, sleep, and wellbeing during shiftwork simulations, but to date there have been very few attempts to administer light treatment to real shiftworkers. We have developed procedures for implementing light treatment and have conducted controlled trials of light treatment for MSFC Payload Operations staff during the USML-1 mission. We found that treatment had beneficial effects on fatigue, alertness, self-rated job performance, sleep, mood, and work attendance. Although there are portable bright light boxes commercially available, there is no testing protocol and little performance information available. We measure the illuminance of two candidate boxes for use in this study and found that levels were consistently lower than those advertised by manufacturers. A device was developed to enhance the illuminance output of such units. This device increased the illuminance by at least 60 % and provided additional improvements in visual comfort and overall exposure. Both the design of this device and some suggested procedures for evaluating light devices are presented.

Hayes, Benita C.↗
NASA NTRS1994

Total hydrocarbon analysis by ion mobility spectrometry

Astronauts must be alerted quickly to chemical leaks that compromise their health and the success of their missions. An ideal leak detector would be equally sensitive to all compounds that might constitute a hazard and insensitive to nontoxic compounds. No ideal sensor exists; thus, selection of a methodology is a series of compromises. The commonly used methods are either insensitive at the low exposure levels set by OSHA, NASA, and other organizations or are selectively insensitive to important classes of chemicals such as Freons. After extensive study and experience, the Toxicology Group at JSC has selected ion mobility spectrometry (IMS) for development into a broad range, sensitive detector. In addition to the sensing method, signal processing is important leak detection because a background signal can be expected at all times. The leak-detecting instrument must be programmed to discriminate between authentic leaks and background fluctuations caused by routine operations. The results of an evaluation of the prototype THA is presented in terms related to spacecraft operations. The evaluation included determination of instrumental parameters such as stability and response times. We also included responses to some common components of spacecraft atmospheres in pure form and in binary and ternary mixtures. The output of the four algorithms to the mixtures was found to be noticeably different. These responses are compared on the basis of their utility for signaling a chemical leak. As a means of evaluating its resistance to a falsely positive response, the THA was challenged with carbon dioxide and methane, compounds whose concentrations normally increase in spacecraft air during human habitation. The instrument showed virtually no response to these interferences. Although the prototype THA is designed for space flight, this detector is expected to be useful for field screening at chemical waste dumps and other environmentally sensitive locations.

Cross, John H.↗
NASA NTRS1993

Case study of a low-reflectivity pulsating microburst - Numerical simulation of the Denver, 8 July 1989, storm

Results from a 3D simulation of a very strong microburst, detected by the Low-Level Windshear Alert System, are presented. The simulation was performed using the Terminal Area Simulation System (TASS) model (Proctor, 1987) which is a 3D nonhydrostatic cloud model that includes parameterizations for both liquid and ice-phase microphysics. Emphasis is placed om the pulsating characteristic and the very-low radar reflectivity of the event. The simulation revealed that the dissipating cloud induces a type-1 pulsating microburst event, with at least three distinct microburst pulses over a period of 20 min.

Proctor, Fred H.↗
NASA NTRS1993

Real-time expert system diagnostics and monitoring for the High Resolution Microwave Survey Targeted Search

An automated monitoring and diagnostics system (MDS) using virtual real-time software was developed for NASA's High Resolution Microwave Survey (HRMS) Targeted Search System (TSS). The four main tasks required of the MDS were monitoring and recording system health, alerting operators of problems, diagnosing poor system performance, and performing an emergency system shutdown. The MDS was implemented using commercial expert system software tools in addition to interface hardware and software developed on site. The expert system used objects, rules, and schematics in its TSS knowledge representation. The MDS was successfully integrated into the HRMS computer environment, and its performance met or exceeded its requirements.

Macalou, A.↗
NASA NTRS1994

Case study of a low-reflectivity pulsating microburst: Numerical simulation of the Denver, 8 July 1989, storm

On 8 July 1989, a very strong microburst was detected by the Low-Level Windshear Alert system (LLWAS), within the approach corridor just north of Denver Stapleton Airport. The microburst was encountered by a Boeing 737-200 in a 'go-around' configuration which was reported to have lost considerable air speed and altitude during penetration. Data from LLWAS revealed a pulsating microburst with an estimated peak velocity change of 48 m/s. Wilson et al. reported that the microburst was accompanied by no apparent visible clues such as rain or virga, although blowing dust was present. Weather service hourly reports indicated virga in all quadrants near the time of the event. A National Center for Atmospheric Research (NCAR) research Doppler radar was operating; but according to Wilson et al., meaningful velocity could not be measured within the microburst due to low radar-reflectivity factor and poor siting for windshear detection at Stapleton. This paper presents results from the three-dimensional numerical simulation of this event, using the Terminal Area Simulation System (TASS) model. The TASS model is a three-dimensional nonhydrostatic cloud model that includes parameterizations for both liquid and ice phase microphysics, and has been used in investigations of both wet and dry microburst case studies. The focus of this paper is the pulsating characteristic and the very-low radar reflectivity of this event. Most of the surface outflow contained no precipitation. Such an event may be difficult to detect by radar.

Proctor, Fred H.↗
NASA NTRS1994

Evaluation of iconic versus F-map microburst displays

Previous studies have shown graphical presentation methods of hazardous wind shear to be superior to textual or audible warnings alone. Positional information and the strength of the hazard were observed to be and were cited by pilots as the most important factors in a display. In this experiment the use of the three different graphical presentations of hazardous wind shear are examined. Airborne predictive detectors of wind shear enable the dissemination of varying levels of information. The effectiveness of iconic and mapping display modes of different complexities are addressed through simulation and analysis. Different positional and time-varying situations are presented in a 'part-task' Boeing 767 simulator using data from actual microburst events. Experienced airline pilots fly approach profiles using both iconic and F-map wind shear alerting displays. Microburst accompanied each event is also shown to the pilot. Mapping display types are expected to be found exceptionally efficient at conveying location comparison information while iconic displays simplify the threat recognition process. Preliminary results from the simulator study are presented. Recommendations concerning the suitability of multilevel iconic and mapping displays are made. Situational problems with current display prototypes are also addressed.

Salzberger, Mark↗
NASA NTRS1992

Airborne rotary separator study

Several air breathing propulsion concepts for future earth-to-orbit transport vehicles utilize air collection and enrichment, and subsequent storage of liquid oxygen for later use in the vehicle mission. Work performed during the 1960's established the feasibility of substantially reducing weight and volume of a distillation type air separator system by operating the distillation elements in high 'g' fields obtained by rotating the separator assembly. The purpose of this study was to evaluate various fuels and fuel combinations with the objective of minimizing the weight and increase the ready alert capability of the plane. Fuels will be used to provide energy as well as act as heat sinks for the on-board heat rejection system. Fuel energy was used to provide power for air separation as well as to produce refrigeration for liquefaction of oxygen enriched air, besides its primary purpose of vehicle propulsion. The heat generated in the cycle was rejected to the fuel and water which is also carried on board the vehicle.The fuels that were evaluated include JP4, methane, and hydrogen. Hydrogen served as a comparison to the JP4 and methane cases.

Drnevich, R. F.↗
NASA NTRS1994

An expert system for diagnosing anomalies of spacecraft

Although the analysis of anomalous behavior of satellites is difficult because it is a very complex process, it is important to be able to make an accurate assessment in a timely manner when the anomaly is observed. Spacecraft operators may have to take corrective action or to 'safe' the spacecraft; space-environment forecasters may have to assess the environmental situation and issue warnings and alerts regarding hazardous conditions, and scientists and engineers may want to gain knowledge for future designs to mitigate the problems. Anomalies can be hardware problems, software errors, environmentally induced, or even the cause of workmanship. Spacecraft anomalies attributable to electrostatic discharges have been known to cause command errors. A goal is to develop an automated system based on this concept to reduce the number of personnel required to operate large programs or missions such as Hubble Space Telescope (HST) and Mission to Planet Earth (MTPE). Although expert systems to detect anomalous behavior of satellites during operations are established, diagnosis of the anomaly is a complex procedure and is a new development.

Lauriente, Michael↗
NASA NTRS1994

JPL space robotics: Present accomplishments and future thrusts

Complex missions require routine and unscheduled inspection for safe operation. The purpose of research in this task is to facilitate structural inspection of the planned Space Station while mitigating the need for extravehicular activity (EVA), and giving the operator supervisory control over detailed and somewhat mundane, but important tasks. The telerobotic system enables inspection relative to a given reference (e.g., the status of the facility at the time of the last inspection) and alerts the operator to potential anomalies for verification and action. There are two primary objectives of this project: (1) To develop technologies that enable well-integrated NASA ground-to-orbit telerobotics operations, and (2) to develop a prototype common architecture workstation which implements these capabilities for other NASA technology projects and planned NASA flight applications. This task develops and supports three telerobot control modes which are applicable to time delay operation: Preview teleoperation, teleprogramming, and supervised autonomy.

Weisbin, C. R.↗
NASA NTRS1995

Technical report series on global modeling and data assimilation. Volume 6: A multiyear assimilation with the GEOS-1 system: Overview and results

The Data Assimilation Office (DAO) at Goddard Space Flight Center has produced a multiyear global assimilated data set with version 1 of the Goddard Earth Observing System Data Assimilation System (GEOS-1 DAS). One of the main goals of this project, in addition to benchmarking the GEOS-1 system, was to produce a research quality data set suitable for the study of short-term climate variability. The output, which is global and gridded, includes all prognostic fields and a large number of diagnostic quantities such as precipitation, latent heating, and surface fluxes. Output is provided four times daily with selected quantities available eight times per day. Information about the observations input to the GEOS-1 DAS is provided in terms of maps of spatial coverage, bar graphs of data counts, and tables of all time periods with significant data gaps. The purpose of this document is to serve as a users' guide to NASA's first multiyear assimilated data set and to provide an early look at the quality of the output. Documentation is provided on all the data archives, including sample read programs and methods of data access. Extensive comparisons are made with the corresponding operational European Center for Medium-Range Weather Forecasts analyses, as well as various in situ and satellite observations. This document is also intended to alert users of the data about potential limitations of assimilated data, in general, and the GEOS-1 data, in particular. Results are presented for the period March 1985-February 1990.

Suarez, Max J.↗
NASA NTRS1995

Meteor stream activity. 2: Meteor outbursts

In the past two centuries, alert amateur and professional meteor astronomers have documented 35 outbursts of 17 individual meteor streams well enough to allow the construction of a homogeneous set of activity curves. These curves add to similar profiles of the annual streams in a previous paper (Paper 1). This paper attempts to define the type and range of phenomena that classify as meteor outbursts from which the following is concluded: Outbursts are associated with the return of the comet to perihelion (near-comet type outbursts), but occur also when the parent comet is far from perihelion and far from the Earth (far-comet type). All outbursts of a given type only, depending on encounter geometry. The activity curves, expressed in terms of Zenith Hourly Rates (ZHR), have a shape that is generally well described by: ZHR = ZHR(sub max) 10(sup(-B (the absolute value of lambda (sub dot in a circle) - lambda (sup max) (sub dot in a circle))). The steepness of the slopes varies from an exponent of B = 7 to B = 220 per degree of solar longitude, with a typical value of B = 30. In addition, most near-comet type outbursts have a broader component underlying the main peak with B approximately 1 - 7.The duration Delta t is approximately 1/B of the main peak is almost independent of location near the comet, while the background component varies considerably in duration and relative intensity from one return to another. The two components in the activity curve are due to two distinct structures in the dust distribution near the parent comet, where the main component can be due to a sheet of dust that emanates from the IRAS dust trail. This brings the total number of distinct structures in meteor streams to four, including the two structures from the annual stream activity in Paper 1.

Jenniskens, P.↗
NASA NTRS1995

Hydrogen-Detection Apparatus

Apparatus continuously monitors concentration of hydrogen, at level ranging from few parts per million to several percent, in mixture of gases. Simple and fast, providing high sensitivity and linear response. Used to alert technicians to potentially explosive concentrations of residual hydrogen.

Ross, H. Richard↗
NASA NTRS1995

Device Would Monitor Body Parameters Continuously

Proposed miniature electronic circuit continuously measures temperature of human subject. Once mounted on subject's skin with medical adhesive tape, electronic thermometer remains in thermal equilibrium with subject's body; thereafter, no need to wait until thermometer reaches body temperature before taking reading. Design provides for switches used to set alarm alerting medical attendants if subject's temperature exceeds critical level. For use on very young child, electronic thermometer sewed into shirt or other suitable garment; device held in contact with skin, and child could not swallow it. Replacement of sensor and computing algorithm changes temperature monitor to cardiorespiratory monitor.

Cook, Joseph S., Jr.↗