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At least 235 records · Page 13

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NASA NTRS1984

Advanced CID array multispectral pushbroom scanner

An optical imager, called the Scanning Imaging Spectroradiometer (SIS), was built for NASA in the early 1970's. Later, the Solidstate Array Spectroradiometer (SAS) was developed on the basis on a substitution of a Charge Injection Device (CID) array for the vidicon of the SIS. The Advanced Solidstate Array Spectroradiometer (ASAS) represents an improvement of the SAS. ASAS is a solidstate multispectral optical imaging radiometer which is currently the most versatile instrument of its type in the visible part of the spectrum. The instrument is capable of absolute radiometric measurements in all of its 32 bands. ASAS can be easily mounted in small aircraft as well as high altitude craft such as the U-2, taking into account also the possibility of a use in the Space Shuttle. The instrument consists of three separate subsystems. Attention is given to the optics, the detector array, data storage, data retrieval, and system performance.

Stewart, S. E.↗

NASA NTRS1989

Results of an A109 simulation validation and handling qualities study

The results for the validation of a mathematical model of the Agusta A109 helicopter, and subsequent use of the model as the baseline for a handling qualities study of cockpit centerstick requirements, are described. The technical approach included flight test, non-realtime analysis, and realtime piloted simulation. Results of the validation illustrate a time- and frequency-domain approach to the model and simulator issues. The final A109 model correlates well with the actual aircraft with the Stability Augmentation System (SAS) engaged, but is unacceptable without the SAS because of instability and response coupling at low speeds. Results of the centerstick study support the current U.S. Army handling qualities requirements for centerstick characteristics.

Eshow, Michelle M.↗

NASA NTRS1989

Further observations of the eclipsing X-ray burst source MXB 1659-29

An analysis is presented of data for MXB 1659-29 obtained during October 2-10, 1976 and June 6-11, 1977 using the SAS 3 X-ray Observatory (Lewin et al., 1976) and during September 8-13, 1978 using the A-1 experiment aboard HEAO 1 (Wood et al., 1984). The data confirm the 7.1 hr orbital period and provide evidence for the 15-min X-ray eclipse reported by Cominsky and Wood (1984). A total of 32 X-ray bursts are detected during the SAS 3 observations. By combining the data with previously published results, the orbital period is found to be about 0.29650474 days.

Cominsky, L. R.↗

NASA NTRS1989

Candidate sample acquisition systems for the Rosetta

The Comet Nucleus Sample Return (CNSR) mission, one of the four cornerstones of the ESA scientific program, is one of the most complex space ventures within the next century, both from technological and deep space exploration point of view. In the Rosetta scenario the sample acquisition phase represents the most critical point for the global mission's success. The proposed paper illustrates the main results obtained in the context of the CNSR-SAS ongoing activity. The main areas covered are related to: (1) sample properties characterization (comet soil model, physical/chemical properties, reference material for testing); (2) concepts identification for coring, shovelling, harpooning and anchoring; (3) preferred concept (trade off among concepts, identification of the preferred configuration); and (4) proposed development activity for gaining the necessary confidence before finalizing the CNSR mission. Particular emphasis will be given to the robotic and flexibility aspects of the identified sample acquisition systems (SAS) configuration, intended as a means for the overall system performance enhancement.

Magnani, P. G.↗

NASA NTRS1990

Results of an A109 simulation validation and handling qualities study

Eshow, Michelle M.↗

NASA NTRS1992

Silicon carbide fiber reinforced strontium aluminosilicate glass-ceramic matrix composite

A SrO-Al2O3 - 2SrO2 (SAS) glass ceramic matrix is reinforced with CVD SiC continuous fibers. This material is prepared by casting a slurry of SAS glass powder into tapes. Mats of continuous CVD-SiC fibers are alternately stacked with the matrix tapes. This tape-mat stack is warm-pressed to produce a 'green' composite. Organic constituents are burned out of the 'green' composite, and the remaining interim material is hot pressed.

Bansal, Narottam↗

NASA NTRS1993

MAC to VAX Connectivity: Heartrate Spectral Analysis System

The heart rate Spectral Analysis System (SAS) acquires and analyzes, in real-time, the Space Shuttle onboard electrocardiograph (EKG) experiment signals, calculates the heartrate, and applies a Fast Fourier Transformation (FFT) to the heart rate. The system also calculates other statistical parameters such as the 'mean heart rate' over specific time period and heart rate histogram. This SAS is used by NASA Principal Investigators as a research tool to determine the effects of weightlessness on the human cardiovascular system. This is also used to determine if Lower Body Negative Pressure (LBNP) is an effective countermeasure to the orthostatic intolerance experienced by astronauts upon return to normal gravity. In microgravity, astronauts perform the LBNP experiment in the mid deck of the Space Shuttle. The experiment data are downlinked by the orbiter telemetry system, then processed and analyzed in real-time by the integrated Life Sciences Data Acquisition (LSDS) - Spectral Analysis System. The data system is integrated within the framework of two different computer systems, VAX and Macintosh (Mac), using the networking infrastructure to assist the investigators in further understanding the most complex machine on Earth--the human body.

Rahman, Hasan H.↗

NASA NTRS1991

Cerebral blood flow - Comparison of ground-based and spaceflight data and correlation with space adaptation syndrome

The relationship between the cerebral blood flow velocity and the space adaptation syndrome (SAS), which includes symptoms of motion sickness, stuffy head, and/or headaches, was investigated by measuring (using a transcranial Doppler device) differences between the preflight and the inflight cerebral blood flow velocity in crew members who were motion sick and in those who were not sick during a flight aboard KC-135. It was found that the cerebral artery bloodflow inflight did not differ significantly from that recorded preflight, nor did the severity of SAS symptoms correlate directly with the cerebral blood flow.

Bagian, James P.↗

NASA NTRS1992

Neurology of microgravity and space travel

Exposure to microgravity and space travel produce several neurologic changes, including SAS, ataxia, postural disturbances, perceptual illusions, neuromuscular weakness, and fatigue. Inflight SAS, perceptual illusions, and ocular changes are of more importance. After landing, however, ataxia, perceptual illusions, neuromuscular weakness, and fatigue play greater roles in astronaut health and readaptation to a terrestrial environment. Cardiovascular adjustments to microgravity, bone demineralization, and possible decompression sickness and excessive radiation exposure contribute further to medical problems of astronauts in space. A better understanding of the mechanisms by which microgravity adversely affects the nervous system and more effective treatments will provide healthier, happier, and longer stays in space on the space station Freedom and during the mission to Mars.

Fujii, M. D.↗

NASA NTRS1994

YAV-8B reaction control system bleed and control power usage in hover and transition

Using a calibrated Rolls-Royce Pegasus engine and existing aircraft instrumentation and pressure taps, total and individual nozzle reaction control system (RCS) bleed flow rates have been measured on a YAV-8B Harrier during typical short takeoff, transition, hover, and vertical landing maneuvers. RCS thrust forces were calculated from RCS nozzle total pressure measurements, and control power was determined from the moments produced by these thrusts and the aircraft's moments of inertia. These data document the characteristics of the YAV-8B RCS with its basic stability augmentation system (SAS) engaged. Advanced control system designs for the YAV-8B can be compared to the original SAS based on the total bleed use and the percentage of available bleed used. In addition, the peak and mean values of the bleed and control power data can be used for sizing the reaction controls for a future short takeoff and vertical landing (STOVL) aircraft.

Borchers, Paul F.↗

NASA NTRS1995

Method of producing a silicon carbide fiber reinforced strontium aluminosilicate glass-ceramic matrix composite

A SrO-Al2O3-2SrO2 (SAS) glass ceramic matrix is reinforced with CVD SiC continuous fibers. This material is prepared by casting a slurry of SAS glass powder into tapes. Mats of continuous CVD-SiC fibers are alternately stacked with the matrix tapes. This tape-mat stack is warm-pressed to produce a 'green' composite. Organic constituents are burned out of the 'green' composite, and the remaining interim material is hot pressed.

Bansal, Narottam P.↗

NASA NTRS2000

The SeaWinds Scatterometer Antenna Subsystem on the QuikScat Spacecraft

In today's environment of "Better, Faster, Cheaper", the ability to produce reliable, flight-proven mechanisms for mission critical applications is more important than ever. Such a mechanism was produced for the QuikScat satellite. The Scatterometer Antenna Subsystem (SAS) is a spin mechanism that continuously rotates a scatterometer antenna, and includes the necessary features (rotary interfaces, drives, launch locks, etc) to allow collection of the scatterometry data that will insure mission success. This paper will discuss the evolution of the SAS from its design heritage on the GGS Polar mission to qualification on the ADEOS II satellite to being a key enabler for the rapid development of the QuikScat Satellite.

Workman, Brian J.↗

NASA NTRS1985

Ambulatory Feedback System

This presentation discusses instrumentation that will be used for a specific event, which we hope will carry on to future events within the Space Shuttle program. The experiment is the Autogenic Feedback Training Experiment (AFTE) scheduled for Spacelab 3, currently scheduled to be launched in November, 1984. The objectives of the AFTE are to determine the effectiveness of autogenic feedback in preventing or reducing space adaptation syndrome (SAS), to monitor and record in-flight data from the crew, to determine if prediction criteria for SAS can be established, and, finally, to develop an ambulatory instrument package to mount the crew throughout the mission. The purpose of the Ambulatory Feedback System (AFS) is to record the responses of the subject during a provocative event in space and provide a real-time feedback display to reinforce the training.

Finger, Herbert↗

NASA NTRS1998

SeaWinds-1B Technology Study Overview

The technology study entailed: 1) evaluating 4 options to improve nominal range resolution from 5.25 Km (QuikScat/SeaWinds - 1A) to 1 Km.; 2) identifying changes and impacts to the SES modules; 3) defined new general purpose DSPs with greater programmability and increased systems flexibility; 4) Developing candidate approach to improve receiver noise figure by 1.4 dB at 25 C. Noise figure improves further to 2.2 dB by cooling the LNA at 0 C; 5) Defining 2 approaches to add a 3rd antenna beam port; and 6) defining packaging concepts using SES-1A modules "as is" on SAS spinning side. Investigated fully repackaged SES on the SAS spinning skirt.

Source record↗

NASA NTRS2000

A Comparison of Three Programming Models for Adaptive Applications

We study the performance and programming effort for two major classes of adaptive applications under three leading parallel programming models. We find that all three models can achieve scalable performance on the state-of-the-art multiprocessor machines. The basic parallel algorithms needed for different programming models to deliver their best performance are similar, but the implementations differ greatly, far beyond the fact of using explicit messages versus implicit loads/stores. Compared with MPI and SHMEM, CC-SAS (cache-coherent shared address space) provides substantial ease of programming at the conceptual and program orchestration level, which often leads to the performance gain. However it may also suffer from the poor spatial locality of physically distributed shared data on large number of processors. Our CC-SAS implementation of the PARMETIS partitioner itself runs faster than in the other two programming models, and generates more balanced result for our application.

Shan, Hong-Zhang↗

NASA NTRS2001

The Evolution of CTB-109

The subject grant is for the analysis of XMM observations of the galactic supernova remnant CTB-109. As of the writing of this report, the XMM observations have not been conducted yet. We have begun gaining experience with the XMM analysis SW and calibration files so that we can more quickly analyze our data once they become available. We have downloaded the latest version of the XMM standard analysis SW (SAS 5.1). We have downloaded some of the public calibration datasets and started manipulating them using the SAS SW.

Plucinsky, Paul↗

NASA NTRS1996

Evaluation of three portable samplers for monitoring airborne fungi

Airborne fungi were monitored at five sample sites with the Burkard portable, the RCS Plus, and the SAS Super 90 air samplers; the Andersen 2-stage impactor was used for comparison. All samplers were calibrated before being used simultaneously to collect 100-liter samples at each site. The Andersen and Burkard samplers retrieved equivalent volumes of airborne fungi; the SAS Super 90 and RCS Plus measurements did not differ from each other but were significantly lower than those obtained with the Andersen or Burkard samplers. Total fungal counts correlated linearly with Cladosporium and Penicillium counts. Alternaria species, although present at all sites, did not correlate with total count or with amounts of any other fungal genera. Sampler and location significantly influenced fungal counts, but no interactions between samplers and locations were found.

NASA Center JSC↗

NASA NTRS2006

Helicopter force-feel and stability augmentation system with parallel servo-actuator

A force-feel system is implemented by mechanically coupling a servo-actuator to and in parallel with a flight control system. The servo-actuator consists of an electric motor, a gearing device, and a clutch. A commanded cockpit-flight-controller position is achieved by pilot actuation of a trim-switch. The position of the cockpit-flight-controller is compared with the commanded position to form a first error which is processed by a shaping function to correlate the first error with a commanded force at the cockpit-flight-controller. The commanded force on the cockpit-flight-controller provides centering forces and improved control feel for the pilot. In an embodiment, the force-feel system is used as the basic element of stability augmentation system (SAS). The SAS provides a stabilization signal that is compared with the commanded position to form a second error signal. The first error is summed with the second error for processing by the shaping function.

Hoh, Roger H.↗