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At least 1,135 records · Page 63

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NASA NTRS1980

The SETI observational plan

The SETI (Search for Extraterrestrial Intelligence) Project's primary thrust is to search the microwave region of the spectrum for signals of extraterrestrial intelligent origin. The project will search a well defined volume of search parameter space using existing antennae and a sophisticated data acquisition and analysis system. Two major components are included, the target survey, which will observe at very high sensitivity all attractive stellar candidates within 75 light years of the Sun, and the sky survey, which will observe the entire celestial sphere at a lower sensitivity.

Berman, A. L.↗

NASA NTRS1980

Mark 3 wideband digital recorder in perspective

The tape recorder used for the Mark 3 data acquisition and processing system is compared with earlier very long baseline interferometry recorders. Wideband 33-1/3 kbpi digital channel characteristics of instrumentation recorders and of a modern video cassette recorder are illustrated. Factors which influenced selection of the three major commercial components (transport, heads, and tape) are discussed. A brief functional description and the reasons for development of efficient signal electronics and necessary auxiliary control electronics are given. The design and operation of a digital bit synchronizer is illustrated as an example of the high degree of simplicity achieved.

Hinteregger, H. F.↗

NASA NTRS1980

High-resolution LDA measurements of Reynolds stress in boundary layers and wakes

The turbulent character of the boundary layer and wake associated with an airfoil has been studied at a Reynolds number of 1,000,000 and a Mach number of 0.1. To accomplish these measurements, a unique laser Doppler anemometer (LDA) has been developed that is capable of sensing two velocity components from a remote distance of 2.13 m. Using special simultaneity logic and counter-type signal processors, the geometrical features of the LDA have been exploited to provide variable spatial resolution as low as 0.2 mm. By combining the LDA with an on-line computerized data acquisition and display system, it has been possible to measure mean velocity and Reynolds stress tensor distribution at several locations along the upper surface of a 0.9-m-chord, flapped airfoil installed in the Ames 7- by 10-Foot Wind Tunnel.

Orloff, K. L.↗

NASA NTRS1981

YF 102 in-duct combustor noise measurements with a turbine nozzle, volume 1

The internal noise generated by an Avco Lycoming YF-102 engine combustor installed in a test rig was recorded. Two configurations were tested one with and one without the first stage turbine nozzle installed. Acoustic probes and accessories were used. Internal dynamic pressure level measurements were made at ten locations within the combustor. The combustor rig, the test procedures, and data acquisition and reduction systems are described. Tables and plots of narrow band and one third octave band pressure level spectra are included.

Wilson, C. A.↗

NASA NTRS1980

The operational use of Landsat for lake quality assessment

A cooperative program between the Wisconsin Department of Natural Resources and the University of Wisconsin for the assessment, with Landsat data, of the trophic status of all the significant inland lakes in Wisconsin is described. The analysis technique is a semiautomatic data acquisition and handling system which, in conjunction with an analytical categorization scheme, can be used for classifying inland lakes into one of seven categories of eutrophication and one of four problem types.

Scarpace, F. L.↗

NASA NTRS1985

Measurements of vector fields with diode array

A polarimeter was designed for high spatial and spectral resolution. It consists of a quarter-wave plate alternately operating in two positions for Stoke-V measurements and an additional quarter-wave plate for Stokes-U and -Q measurements. The spatial range covers 75 arcsec, the spectral window of about 1.8 a allows the simultaneous observations of neighboring lines. The block diagram of the data processing and acquisition system consists of five memories each one having a capacity of 10 to the 4th power 16-bit words. The total time to acquire profiles of Stokes parameters can be chosen by selecting the number of successive measurements added in the memories, each individual measurement corresponding to an integration time of 0.5 sec. Typical values range between 2 and 60 sec depending on the brightness of the structure, the amount of polarization and a compromise between desired signal-to-noise ratio and spatial resolution.

Wiehr, E. J.↗

NASA NTRS1985

Observation of energy spectrum of electron albedo in low latitude region at Hyderabad, India

The preliminary results are presented of the measurement of the energy spectrum of low energy (5-24 MeV) albedo electrons, moving upward as well as downwards, at about 37 km (-4 mb) altitude, over Hyderabad, India, in low latitude region. The flux and energy spectrum was observed by a bi-directional, multidetector charged particle telescope which was flown in a high altitude balloon on 8th December 1984. Results based on a quick look data acquisition and analysis system are presented here.

Verma, S. D.↗

NASA NTRS1987

Computer controlled facility for measurement of the bidirectional scattering distribution function

A computer controlled facility for measurement of the bidirectional scattering distribution function is described, with application to the evaluation of spacecraft surface contamination in optical and thermal control systems. An automatic detector/sampleholder allows a 360-deg detector scan around the sample for a complete bidirectional reflectance and transmittance distribution function characterization. The system demonstrates reduced data acquisition and reduction cycle time, and improved accuracy.

Carosso, Paolo A.↗

NASA NTRS1986

A model propulsion simulator for evaluating counter rotating blade characteristics

Three Model Propulsion Simulators (MPS) were designed and built to evaluate candidate counterrotation Ultra bypass fan model blade designs of nominally 2-ft (0.61 m) tip diameter for an advanced 'pusher-type' aircraft engine. These propulsion simulators (nominally 1/5 engine size) are capable of operation over a wide range of subsonic conditions and can deliver up to 750 shaft horsepower per rotor at rotor speeds of 10,000 rpm. The rotor thrust and torque, dynamic blade stresses, and system temperature data are transmitted through an integral telemetry system to facilitate data acquisition. Salient features of the design, instrumentation, and operation of these simulators are described in this paper.

Delaney, B. R.↗

NASA NTRS1986

Operation of the HP2250 with the HP9000 series 200 using PASCAL 3.0

A computer program has been written to provide an interface between the HP Series 200 desktop computers, operating under HP Standard Pascal 3.0, and the HP2250 Data Acquisition and Control System. Pascal 3.0 for the HP9000 desktop computer gives a number of procedures for handling bus communication at various levels. It is necessary, however, to reach the lowest possible level in Pascal to handle the bus protocols required by the HP2250. This makes programming extremely complex since these protocols are not documented. The program described solves those problems and allows the user to immediately program, simply and efficiently, any measurement and control language (MCL/50) application with a few procedure calls. The complete set of procedures is available on a 5 1/4 inch diskette from Cosmic. Included in this group of procedures is an Exerciser which allows the user to exercise his HP2250 interactively. The exerciser operates in a fashion similar to the Series 200 operating system programs, but is adapted to the requirements of the HP2250. The programs on the diskette and the user's manual assume the user is acquainted with both the MCL/50 programming language and HP Standard Pascal 3.0 for the HP series 200 desktop computers.

Perry, John↗

NASA NTRS1989

A noncontacting scanning photoelectron emission technique for bonding surface cleanliness inspection

Molecular contamination of bonding surfaces can drastically affect the bond strength that can be achieved and therefore the structural integrity and reliability of the bonded part. The presence of thin contaminant films on bonding surfaces can result from inadequate or incomplete cleaning methods, from oxide growth during the time between cleaning (such as grit blasting) and bonding, or from failure to properly protect cleaned surfaces from oils, greases, fingerprints, release agents, or deposition of facility airborne molecules generated by adjacent manufacturing or processing operations. Required cleanliness levels for desired bond performance can be determined by testing to correlate bond strength with contaminant type and quantity, thereby establishing the degree of contamination that can be tolerated based on the strength that is needed. Once the maximum acceptable contaminant level is defined, a method is needed to quantitatively measure the contaminant level on the bonding surface prior to bonding to verify that the surface meets the established cleanliness requirement. A photoelectron emission technique for the nondestructive inspection of various bonding surfaces, both metallic and nonmetallic, to provide quantitative data on residual contaminant levels is described. The technique can be used to scan surfaces at speeds of at least 30 ft/min using a servo system to maintain required sensor to surface spacing. The fundamental operation of the photoelectron emission sensor system is explained and the automated scanning system and computer data acquisition hardware and software are described.

Gause, Raymond L.↗

NASA NTRS1990

Measurement of crossflow vortices, attachment-line flow, and transition using microthin hot films

A flow diagnostic experiment was conducted on a 45-deg swept-wing model using surface-mounted, multielement, microthin, hot-film sensors. The cross-flow vortex spacing, the attachment-line flow characteristics, and the transition region were all determined using an advanced data acquisition and instrumentation system. In addition to the frequencies of traveling waves predicted by linear stability theory, amplified disturbances at much higher frequencies were observed. Simultaneous measurements from sensors located at a number of chord and span locations highlighted the strong three-dimensionality of the boundary-layer flow in the presence of cross-flow vortices. The state of the attachment-line boundary layer was determined using a multielement sensor wrapped around the wing leading edge. The transition region flow characteristics were also identified.

Mangalam, S. M.↗

NASA NTRS1990

Particle displacement tracking for PIV

A new Particle Imaging Velocimetry (PIV) data acquisition and analysis system, which is an order of magnitude faster than any previously proposed system has been constructed and tested. The new Particle Displacement Tracing (PDT) system is an all electronic technique employing a video camera and a large memory buffer frame-grabber board. Using a simple encoding scheme, a time sequence of single exposure images are time coded into a single image and then processed to track particle displacements and determine velocity vectors. Application of the PDT technique to a counter-rotating vortex flow produced over 1100 velocity vectors in 110 seconds when processed on an 80386 PC.

Wernet, Mark P.↗

NASA NTRS1990

The crop growth research chamber: A ground-based facility for CELSS research

A ground based facility for the study of plant growth and development under stringently controlled environments is being developed by the Closed Ecological Life Support System (CELSS) program at the Ames Research Center. Several Crop Growth Research Chambers (CGRC) and laboratory support equipment provide the core of this facility. The CGRC is a closed (sealed) system with a separate recirculating atmosphere and nutrient delivery systems. The atmospheric environment, hydroponic environment, systems controls, and data acquisition are discussed.

Bubenheim, David L.↗

NASA NTRS1990

Wave-particle interactions on the FAST satellite

NASA's Fast Auroral Snapshot, or 'FAST' satellite, scheduled for launch in 1993, will investigate the plasma physics of the low altitude auroral zone from a 3500-km apogee polar orbit. FAST will give attention to wave, double-layer, and soliton production processes due to electrons and ions, as well as to wave-wave interactions, and the acceleration of electrons and ions by waves and electric fields. FAST will employ an intelligent data-handling system capacle of data acquisition at rates of up to 1 Mb/sec, in addition to a 1-Gbit solid-state memory. The data need be gathered for only a few minutes during passes through the auroral zone, since the most interesting auroral phenomena occur in such narrow regions as auroral arcs, electrostatic shocks, and superthermal electron bursts.

Temerin, M. A.↗

NASA NTRS1991

Two-dimensional particle displacement tracking in particle imaging velocimetry

A new particle imaging velocimetry data acquisition and analysis system, which is an order of magnitude faster than any previously proposed system, has been constructed and tested. The new particle displacement tracking (PDT) system is an all electronic technique employing a video camera and a large memory buffer frame-grabber board. Using a simple encoding scheme, a time sequence of single exposure images is time-coded into a single image and then processed to track particle displacements and determine two-dimensional velocity vectors. Use of the PDT technique in a counterrotating vortex flow produced over 1100 velocity vectors in 110 s when processed on an 80386 PC.

Wernet, Mark P.↗

NASA NTRS1992

Menu-Driven Program Displays Data In Real Time

JPL/VIEW is menu-driven program retrieving and displaying incoming propagation data as they reach hard disk of data-acquisition-and-storage system. Real-time display enables operator to monitor progress of events and respond swiftly to errors during experiment or trial operation. Written in Microsoft C.

Mckeeman, John C.↗

NASA NTRS1991

Pilot's Automated Weather Support System (PAWSS) concepts demonstration project. Phase 1: Pilot's weather information requirements and implications for weather data systems design

The weather information requirements for pilots and the deficiencies of the current aviation weather support system in meeting these requirements are defined. As the amount of data available to pilots increases significantly in the near future, expert system technology will be needed to assist pilots in assimilating that information. Some other desirable characteristics of an automation-assisted system for weather data acquisition, dissemination, and assimilation are also described.

Crabill, Norman L.↗