Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “alertness”

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 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

Search and rescue satellite-aided tracking system

The objective of Sarsat is to demonstrate that satellites can greatly facilitate the monitoring, detection, and location of distress incidents alerted by Emergency Locator Transmitters (ELTs) and Emergency Position Indicating Radio Beacons (EPIRBs) carried on commercial, military, and general aviation aircraft and some marine vessels. The detection and location will be accomplished by relaying, via satellite, ELT/EPIRB distress information to ground stations, which will complete the data processing and forward alert and position location data to rescue coordination services. This paper presents a Sarsat system description and a summary of Coast Guard and USAF objectives for the initial demonstration and evaluation tests of Sarsat.

Trudell, B.↗
NASA NTRS1982

Temperature and behavioral responses of squirrel monkeys to 2Gz acceleration

This study examines the responses of squirrel monkeys to acute +2Gz exposure. Body temperature responses of loosely restrained animals were recorded via a thermistor in the colon. Behavioral responses were recorded by video monitoring. After baseline recording at 1G, monkeys were exposed to 2G for 60 min. The body temperature started to fall within 10 min of the onset of centrifugation and declined an average of 1.4 C in 60 min. This is in contrast to a stable body temperature during the control period. Further, after a few minutes at 2G, the animals became drowsy and appeared to fall asleep. During the control period, however, they were alert and continually shifting their gaze about the cage. Thus, primates are susceptible to hypergravic fields in the +Gz orientation. The depression in primate body temperature was consistent and significant. Further, the observed drowsiness in this study has significant ramifications regarding alertness and performance in man.

Fuller, C. A.↗
NASA NTRS1984

Human factors in cockpit automation

The rapid advance in microprocessor technology has made it possible to automate many functions that were previously performed manually. Several research areas have been identified which are basic to the question of the implementation of automation in the cockpit. One of the identified areas deserving further research is warning and alerting systems. Modern transport aircraft have had one after another warning and alerting systems added, and computer-based cockpit systems make it possible to add even more. Three major areas of concern are: input methods (including voice, keyboard, touch panel, etc.), output methods and displays (from traditional instruments to CRTs, to exotic displays including the human voice), and training for automation. Training for operating highly automatic systems requires considerably more attention than it has been given in the past. Training methods have not kept pace with the advent of flight-deck automation.

Wiener, E. L.↗
NASA NTRS1986

Vertical structure of Arctic haze observed by lidar

In the study of the Arctic Haze phenomenon, understanding the vertical structure of the haze aerosol is crucial in defining mechanisms of haze transport. Questions have also arisen concerning the representativeness of surface observations of Arctic Haze. Due to the strongly stratified nature of the Arctic troposphere, the mechanisms which transport aerosol to the surface from the transport altitudes of the lower troposphere are not obvious. In order to examine these questions, a Mie scattering lidar was installed at Alert, NWT, Canada. Lidar observes atmospheric aerosols and hydrymeteors as they appear in nature, unmodified by sampling effects. As such the results obtained are more realistic of the light scattering characteristics of the in situ aerosol than are those obtained by integrating nephelometers, for example, which heat the aerosol and dry it before measurement. With this lidar, a pulse was transmitted vetically through an evacuated tube in the roof of a building at Alert. The receiver consisted of a 20cm diameter Fresnel telescope, neutral density and polarizing filters, and RCA C31000A PMT, Analog Modules LA-90-P logarithmic amplifier and a Lecroy TR8827 32 MHz digitizer. The lidar equation was solved for the backscattering coefficient of the aerosol assuming no two way transmission losses in the signal. The lidar results have shown that intercomparison between lidar obtained visibilities and observer visibilities are in much better agreement than for other optical or aerosol monitors. Three new effects were identified in the lidar profiles which contribute to the vertical transport of haze. These effects are briefly discussed.

Hoff, R. M.↗
NASA NTRS1988

Physiological measures and mental-state assessment

General considerations regarding monitoring of operators for alertness are discussed, including who should be monitored and what information should be collected. Measures that have been used to ascertain more general and persistent states of alertness are outlined, including cardiac activity, peripheral vascular activity, skin conductance, electroencephalography, pupillography, oculomotor activity, and body movements.

Stern, John A.↗
NASA NTRS1988

Likelihood alarm displays

In a likelihood alarm display (LAD) information about event likelihood is computed by an automated monitoring system and encoded into an alerting signal for the human operator. Operator performance within a dual-task paradigm was evaluated with two LADs: a color-coded visual alarm and a linguistically coded synthetic speech alarm. The operator's primary task was one of tracking; the secondary task was to monitor a four-element numerical display and determine whether the data arose from a 'signal' or 'no-signal' condition. A simulated 'intelligent' monitoring system alerted the operator to the likelihood of a signal. The results indicated that (1) automated monitoring systems can improve performance on primary and secondary tasks; (2) LADs can improve the allocation of attention among tasks and provide information integrated into operator decisions; and (3) LADs do not necessarily add to the operator's attentional load.

Sorkin, Robert D.↗
NASA NTRS1988

Airborne measurements of tropospheric ozone destruction and particulate bromide formation in the Arctic

Aircraft profiles of O3 concentrations over the Arctic ice pack in spring exhibit a depletion of O3 beneath the surface temperature inversion. One such profile from the NOAA WP-3D Arctic Gas and Aerosol Sampling Program (AGASP) flights in April, 1986 north of Alert, NWT (YLT, 82.5 N) is shown. The gradient of O3 across the temperature inversion, which is essentially a step function from tropospheric values (35 to 40 ppbv) to 0, is somewhat masked by a 1-min running mean applied to the data. Evidence is presented that O3 destruction beneath the Arctic temperature inversion is the result of a photochemical reaction between gaseous Br compounds and O3 to produce particulate Br aerosol. It is noted that in springtime, O3 at the Alert Baseline Station regularly decreases from 30 to 40 ppbv to near 0 over the period of a few hours to a day. At the same time, there is a production of particulate Br with a near 1.0 anti-correlation to O3 concentration. Surface concentrations of bromoform in the Arctic exhibit a rapid decrease following polar sunrise. AGASP aircraft measurements of filterable bromine particulates in the Arctic (March-April, 1983 and 1986) are shown. The greatest concentrations of Br aerosol (shown as enrichment factors relative to to Na in seawater, EFBR (Na)) were observed in samples collected beneath the surface temperature inversion over ice. Samples collected at the same altitude over open ocean (off Spitzbergen) labeled Marine did not exhibit similar Br enrichments. A second region of particulate Br enrichment was observed in the lower stratosphere, which regularly descends to below 500 mb (5.5 km) in the high Arctic. The NOAA WP-3D flew in the stratosphere on all AGASP flights and occasionally measured O3 concentrations in excess of 300 ppbv.

Schnell, Russell C.↗
NASA NTRS1990

Evaluation Of An Aircraft-Collision-Avoidance System

Report describes study of pilots' use of traffic alert and collision-avoidance system (TCAS II) in simulated airplane flights. Gives alert by light and sound when another aircraft within 40 s of passing very closely. If other aircraft still poses threat 15 to 20 s later, TCAS II advises pilot to maneuver vertically or to continue on same flightpath but alter rate of ascent or descent. Report describes methodology, summarizes results, and presents conclusions.

Chappell, Sheryl L.↗
NASA NTRS1990

Relative merits of reactive and forward-look detection for wind-shear encounters during landing approach for various microburst escape strategies

The goal was to quantify the benefits of airborne forward-look windshear detection and to develop and test a candidate set of strategies for recovery from inadvertent microburst encounters during the landing approach, given the utilization of both reactive-only and forward-look windshear detection. Candidate strategies were developed and evaluated using a non-piloted simulation consisting of a simple point-mass performance model of a transport-category airplane flying through an analytical microburst model. The results indicate that the factor which most strongly effects a microburst recovery is the time at which the recovery is initiated. Forward-look alerts given 10 seconds prior to microburst entry permitted recoveries to be made with negligible altitude loss. The results also show that no single microburst scenario can be used to evaluate the relative merits of various recovery strategies. The type of alert used to initiate the recovery (reactive or forward-look) and the altitude of the microburst encounter had an effect on the type of recovery strategy that performed best. These factors may have serious implications for the design and certification of windshear systems.

Hinton, David A.↗
NASA NTRS1990

Terminal weather information management

Since the mid-1960's, microburst/windshear events have caused at least 30 aircraft accidents and incidents and have killed more than 600 people in the United States alone. This study evaluated alternative means of alerting an airline crew to the presence of microburst/windshear events in the terminal area. Of particular interest was the relative effectiveness of conventional and data link ground-to-air transmissions of ground-based radar and low-level windshear sensing information on microburst/windshear avoidance. The Advanced Concepts Flight Simulator located at Ames Research Center was employed in a line oriented simulation of a scheduled round-trip airline flight from Salt Lake City to Denver Stapleton Airport. Actual weather en route and in the terminal area was simulated using recorded data. The microburst/windshear incident of July 11, 1988 was re-created for the Denver area operations. Six experienced airline crews currently flying scheduled routes were employed as test subjects for each of three groups: (1) A baseline group which received alerts via conventional air traffic control (ATC) tower transmissions; (2) An experimental group which received alerts/events displayed visually and aurally in the cockpit six miles (approx. 2 min.) from the microburst event; and (3) An additional experimental group received displayed alerts/events 23 linear miles (approx. 7 min.) from the microburst event. Analyses of crew communications and decision times showed a marked improvement in both situation awareness and decision-making with visually displayed ground-based radar information. Substantial reductions in the variability of decision times among crews in the visual display groups were also found. These findings suggest that crew performance will be enhanced and individual differences among crews due to differences in training and prior experience are significantly reduced by providing real-time, graphic display of terminal weather hazards.

Lee, Alfred T.↗
NASA NTRS1990

Flight experience with windshear detection

Windshear alerts resulting from the Honeywell Windshear Detection and Guidance System are presented based on data from approximately 248,000 revenue flights at Piedmont Airlines. The data indicate that the detection system provides a significant benefit to the flight crew of the aircraft. In addition, nuisance and false alerts were found to occur at an acceptably low rate to maintain flight crew confidence in the system. Data from a digital flight recorder is also presented which shows the maximum and minimum windshear magnitudes recorded for a representative number of flights in February, 1987. The effect of the boundary layer of a steady state wind is also discussed.

Zweifel, Terry↗
NASA NTRS1991

Microburst avoidance simulation tests

Implementation issues for uplinked microburst alerts are presented in the form of view-graphs. The following topics are covered: evaluation, transmission, and presentation of ground-based Doppler weather radar derived information through a limited bandwidth digital data link; electronic cockpit presentation of uplinked wind shear alerts (pilot opinion survey, part-task simulation experiment); presentation modes (verbal, textual, and graphical); and ground evaluation of ground-measures wind shear data.

Hansman, John↗
NASA NTRS1991

NSI operations center

The NASA Science Internet (NSI) Network Operations Staff is responsible for providing reliable communication connectivity for the NASA science community. As the NSI user community expands, so does the demand for greater interoperability with users and resources on other networks (e.g., NSFnet, ESnet), both nationally and internationally. Coupled with the science community's demand for greater access to other resources is the demand for more reliable communication connectivity. Recognizing this, the NASA Science Internet Project Office (NSIPO) expands its Operations activities. By January 1990, Network Operations was equipped with a telephone hotline, and its staff was expanded to six Network Operations Analysts. These six analysts provide 24-hour-a-day, 7-day-a-week coverage to assist site managers with problem determination and resolution. The NSI Operations staff monitors network circuits and their associated routers. In most instances, NSI Operations diagnoses and reports problems before users realize a problem exists. Monitoring of the NSI TCP/IP Network is currently being done with Proteon's Overview monitoring system. The Overview monitoring system displays a map of the NSI network utilizing various colors to indicate the conditions of the components being monitored. Each node or site is polled via the Simple Network Monitoring Protocol (SNMP). If a circuit goes down, Overview alerts the Network Operations staff with an audible alarm and changes the color of the component. When an alert is received, Network Operations personnel immediately verify and diagnose the problem, coordinate repair with other networking service groups, track problems, and document problem and resolution into a trouble ticket data base. NSI Operations offers the NSI science community reliable connectivity by exercising prompt assessment and resolution of network problems.

Zanley, Nancy L.↗
NASA NTRS1990

Cockpit napping

The results of a NASA-sponsored study examining the effectiveness of a brief, preplanned cockpit rest period to improve pilot alertness and performance in nonaugmented long-haul flight operations are discussed. Four regularly scheduled trans-Pacific flight legs were studied. The shortest flight legs were about 7 h and the longest about 9.5 h, with duty periods averaging about 11 h and layovers about 25 h. Three-person B747 crews were divided randomly into two volunteer pilot groups. These crews were nonaugmented, and therefore no relief pilots were available. The rest group, consisting of four crews, was allowed a 40 min opportunity to rest during the overwater cruise portion of the flight. On a preplanned, rotating basis, individual crew members were allowed to nap. It is concluded that a preplanned cockpit nap is associated with significantly better behavioral performance and higher levels of physiological alertness and that this can be accomplished without disrupting normal flight operations or compromising safety.

Graeber, R. Curtis↗
NASA NTRS1991

Light as a chronobiologic countermeasure for long-duration space operations

Long-duration space missions require adaptation to work-rest schedules which are substantially shifted with respect to earth. Astronauts are expected to work in two-shift operations and the environmental synchronizers (zeitgebers) in a spacecraft differ significantly from those on earth. A study on circadian rhythms, sleep, and performance was conducted by exposing four subjects to 6 deg head-down tilt bedrest (to simulate the effects of the weightless condition) and imposing a 12-h shift (6 h delay per day for two days). Bright light was tested in a cross-over design as a countermeasure for achieving faster resynchronization and regaining stable conditions for sleep and circadian rhythmicity. Data collection included objective sleep recording, temperature, heart rate, and excretion of hormones and electrolytes as well as performance and responses to questionnaires. Even without a shift in the sleep-wake cycle, the sleep quantity, circadian amplitudes and 24 h means decreased in many functions under bedrest conditions. During the shift days, sleepiness and fatigue increased, and alertness decreased. However, sleep quantity was regained, and resynchronization was completed within seven days after the shift for almost all functions, irrespective of whether light was administered during day-time or night-time hours. The time of day of light exposure surprisingly appeared not to have a discriminatory effect on the resynchronization speed under shift and bedrest conditions. The results indicate that simulated weightlessness alters circadian rhythms and sleep, and that schedule changes induce additional physiological disruption with decreased subjective alertness and increased fatigue. Because of their operational implications, these phenomena deserve additional investigation.

Samel, Alexander↗
NASA NTRS1993

Hazard evaluation and operational cockpit display of ground-measured windshear data

Low-altitude windshear is the leading weather-related cause of fatal aviation accidents in the U.S. Since 1964, there have been 26 accidents attributed to windshear resulting in over 500 fatalities. Low-altitude windshear can take several forms, including macroscopic forms such as cold-warm gustfronts down to the small, intense downdrafts known as microbursts. Microbursts are particularly dangerous and difficult to detect due to their small size, short duration, and occurrence under both heavy precipitation and virtually dry conditions. For these reasons, the real-time detection of windshear hazards is a very active field of research. Also, the advent of digital ground-to-air datalinks and electronic flight instrumentation opens up many options for implementation of windshear alerts in the terminal area environment. Study is required to determine the best content, format, timing, and cockpit presentation of windshear alerts in the modern ATC environment to best inform the flight crew without significantly increasing crew workload.

Wanke, Craig↗
NASA NTRS1993

Multi Wave Link: An interactive database for co-ordination of multiwavelength programs

Multi Wave Link is an operational database used by the international astronomical community to plan and coordinate multiwavelength observational campaigns on various celestial objects. This facility has been and continues to be an essential tool for the organization of numerous simultaneous ground-based and satellite observations. The Multi Wave Link system has both an interactive component and an electronic mail alert notice component. The interactive portion contains a database of schedules from several of the world's larger observatories and orbiting satellites. Lists of observers, observatories, and their available instrumentation are additionally contained in the system. Another feature added to the software allows the user to search the Royal Greenwich Observatory e-mail listing of international astronomers. This capability is often used by astronomers to find the electronic address of colleagues for improved communication. However, the most productive aspect of the Multi Wave Link system appears to be one of the simplest parts of the system: the electronic mail alert notices for observing campaigns. Information useful in planning the structure of future astronomical databases can be obtained by studying patterns of use of the Multi Wave Link system. This paper analyzes 22 months of Multi Wave Link usage from Sep. 1991 - Jul. 1993.

Cordova, France↗
NASA NTRS1994

A graphical workstation based part-task flight simulator for preliminary rapid evaluation of advanced displays

Advances in avionics and display technology are significantly changing the cockpit environment in current transport aircraft. The MIT Aeronautical Systems Lab (ASL) developed a part-task flight simulator specifically to study the effects of these new technologies on flight crew situational awareness and performance. The simulator is based on a commercially-available graphics workstation, and can be rapidly reconfigured to meet the varying demands of experimental studies. The simulator was successfully used to evaluate graphical microbursts alerting displays, electronic instrument approach plates, terrain awareness and alerting displays, and ATC routing amendment delivery through digital datalinks.

Wanke, Craig↗