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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Structural analysis of the controlled impact demonstration of a jet transport airplane

An analytical method has been developed for assessing crash dynamics of large transport aircraft, such as in the NASA Controlled Impact Demonstration (CID) jet crash test on December 1, 1984. The DYCAST nonlinear finite-element computer code was used in a series of progressively more difficult tasks to model complete transport aircraft crashes. Single aircraft frames and fuselage section vertical drop tests were modeled and analyzed to obtain comparisons with experimental data and to develop hybrid element crash springs for use in the large CID model. Predictions of crash and acceleration levels from a symmetric CID model agreed well with data from the CID experiment.

Fasanella, E. L.↗
NASA NTRS1991

Computer integrated documentation

The main technical issues of the Computer Integrated Documentation (CID) project are presented. The problem of automation of documents management and maintenance is analyzed both from an artificial intelligence viewpoint and from a human factors viewpoint. Possible technologies for CID are reviewed: conventional approaches to indexing and information retrieval; hypertext; and knowledge based systems. A particular effort was made to provide an appropriate representation for contextual knowledge. This representation is used to generate context on hypertext links. Thus, indexing in CID is context sensitive. The implementation of the current version of CID is described. It includes a hypertext data base, a knowledge based management and maintenance system, and a user interface. A series is also presented of theoretical considerations as navigation in hyperspace, acquisition of indexing knowledge, generation and maintenance of a large documentation, and relation to other work.

Boy, Guy↗
NASA NTRS1977

Single heterostructure lasers of PbS/1-x/Se/x/ and Pb/1-x/Sn/x/Se with wide tunability

Single-heterostructure diode lasers formed by compositional interdiffusion (CID) and liquid-phase epitaxy (LPE) of lead salts are discussed. The CID technique, which involves creation of a single heterostructure in a pseudobinary compound having binary constituents with different vapor pressures, is reviewed; growth of lead-salt crystals of various compositions is described. Some electrical and optical characteristics, including properties indicative of high internal quantum efficiencies, are given for lasers which employ the CID and LPE diodes. High operating temperatures (i.e., liquid nitrogen levels and above), together with wide tuning ranges (a diode wavelength of 12.7 microns is reported), make the lasers useful in high-resolution spectrometry and advanced trace-gas monitoring systems.

Linden, K. J.↗
NASA NTRS1979

Charge injection device as a candidate sensor for stellar tracking

Charge transfer devices (CTDs) are superior to the image dissector as stellar tracking sensors, considering their low voltage requirements, insensitivity to magnetic fields, good linearity, and low weight and power. An analysis of one type of CTD, called the charge injection device (CID), revealed an X-Y addressing capability which provides exceptional flexibility in array readout and results in enhanced S/N capability, a surface channel device which produces a larger dynamic range of operation, and exceptional and unique tolerance to optical overloads. A 128 row by 128 column CID array processed on silicon was evaluated in a cooled breadboard camera, and measured results indicate projected performance parameters of a large area CID array as follows: 20 micron square sensing site, noise not greater than 25 carriers per pixel, quantum yield of approximately 40% from 0.4 to 1.0 micron, and cooling requirements on the order of 0 degrees C.

Jones, C. S., Jr.↗
NASA NTRS1982

An advanced tracker design for pointing and control of space vehicles using the charge injection device

The use of charge transfer devices (CTD) in pointing and control of space vehicles is examined, with emphasis on the use of charge injection devices (CID). The selection of CTD type and CID operation, including CID signal and noise analysis and signal improvement, are discussed. Star tracking operational advantages of the CTD are pointed out, and the tracking optical concept is discussed and graphically depicted. The position interpolation procedure and the effects of rate of stellar motion on position interpolation are considered, and error analysis is examined. Finally, the breadboard and test program are discussed in detail, coarse and fine acquisition, test for star, track pattern, test procedure and results. An overall accuracy performance of approximately 0.02 pixels or approximately 0.8 arcsec for the test equipment and tracker was obtained.

Jones, C.↗
NASA NTRS1986

Structural dynamics research in a full-scale transport aircraft crash test

A remotely piloted air-to-ground crash test of a full-scale transport aircraft was conducted for the first time for two purposes: (1) to demonstrate performance of an antimisting fuel additive in suppressing fire in a crash environment, and (2) to obtain structural dynamics data under crash conditions for comparison with analytical predictions. The test, called the Controlled Impact Demonstration (CID), was sponsored by FAA and NASA with cooperation of industry, the Department of Defense, and the British and French governments. The test aircraft was a Boeing 720 jet transport. The aircraft impacted a dry lakebed at Edwards Air Force Base, CA. The purpose of this paper is to discuss the structural aspects of the CID. The fuselage section tests and the CID itself are described. Structural response data from these tests are presented and discussed. Nonlinear analytical modeling efforts are described, and comparisons between analytical results and experimental results are presented.

Mccomb, H. G., Jr.↗
NASA NTRS1993

Facilitating access to information in large documents with an intelligent hypertext system

Retrieving specific information from large amounts of documentation is not an easy task. It could be facilitated if information relevant in the current problem solving context could be automatically supplied to the user. As a first step towards this goal, we have developed an intelligent hypertext system called CID (Computer Integrated Documentation) and tested it on the Space Station Freedom requirement documents. The CID system enables integration of various technical documents in a hypertext framework and includes an intelligent context-sensitive indexing and retrieval mechanism. This mechanism utilizes on-line user information requirements and relevance feedback either to reinforce current indexing in case of success or to generate new knowledge in case of failure. This allows the CID system to provide helpful responses, based on previous usage of the documentation, and to improve its performance over time.

Mathe, Nathalie↗
NASA NTRS1995

Proton affinity determinations and proton-bound dimer structure indications in C2 to C15, (alpha),(omega)-alkyldiamines

The 'kinetic method' was used to determine the proton affinity (PA) of a,coalkyldiamines from collision induced dissociation (CID) studies of protonated heterodimers. These PA values were consistently lower than those reported in the proton affinity scale. The apparent discrepancy was rationalized in terms of differences in the conformation of the protonated diamine monomers. The minimum energy species, formed by equilibrium proton transfer processes, have a cyclic conformation and the ion charge is shared by both amino-groups which are bridged by the proton. On the other hand, the species formed through dissociation of protonated dimers have a linear structure and the charge is localized on one of the amino-groups. Thus, the difference in the PA values obtained by both methods is a measure of the additional stability acquired by the protonated diamines through cyclization and charge delocalization. The major collision dissociation pathway of the protonated diamine monomers involved elimination of an ammonia moiety. Other reactions observed included loss of the second amino-group and several other bond cleavages. CID of the protonated dimers involved primarily formation of a protonated monomer through cleavage of the weaker hydrogen bond and subsequently loss of ammonia at higher collision energies. As observed from the CID studies, doubly charged ions were also formed from the diamines under conditions of the electrospray ionization.

Karpas, Z.↗
NASA NTRS1975

Planetary investigation utilizing an imaging spectrometer system based upon charge injection technology

An intrinsic silicon charge injection device (CID) television sensor array has been used in conjunction with a CaMoO4 colinear tunable acousto optic filter, a 61 inch reflector, a sophisticated computer system, and a digital color TV scan converter/computer to produce near IR images of Saturn and Jupiter with 10A spectral resolution and approximately 3 inch spatial resolution. The CID camera has successfully obtained digitized 100 x 100 array images with 5 minutes of exposure time, and slow-scanned readout to a computer. Details of the equipment setup, innovations, problems, experience, data and final equipment performance limits are given.

Wattson, R. B.↗
NASA NTRS1977

Advanced development of Pb-salt semiconductor lasers for the 8.0 to 15.0 micrometer spectral region

The technology was studied for producing Pb-salt diode lasers for the 8-51 micron spectral region suitable for use as local oscillators in a passive Laser Heterodyne Spectrometer (LHS). Consideration was given to long range NASA plans for the utilization of the passive LHS in a space shuttle environment. The general approach was to further develop the method of compositional interdiffusion (CID) recently reported, and used successfully at shorter wavelength. This technology was shown to provide an effective and reproducible method of producing a single-heterostructure (SH) diode of either the heterojunction or single-sided configuration. Performance specifications were exceeded in several devices, with single-ended CW power outputs as high as 0.88 milliwatts in a mode being achieved. The majority of the CID lasers fabricated had CW operating temperatures of over 60K; 30% of them operated CW above the boiling temperature of liquid nitrogen. CW operation above liquid nitrogen temperature was possible for wavelengths as long as 10.3 microns. Operation at 77K is significant with respect to space shuttle operations since its allows considerable simplification of cooling method.

Linden, K. J.↗
NASA NTRS1979

Design, fabrication, and delivery of a charge injection device as a stellar tracking device

Six 128 x 128 CID imagers fabricated on bulk silicon and with thin polysilicon upper-level electrodes were tested in a star tracking mode. Noise and spectral response were measured as a function of temperature over the range of +25 C to -40 C. Noise at 0 C and below was less than 40 rms carriers/pixel for all devices at an effective noise bandwidth of 150 Hz. Quantum yield for all devices averaged 40% from 0.4 to 1.0 microns with no measurable temperature dependence. Extrapolating from these performance parameters to those of a large (400 x 400) array and accounting for design and processing improvements, indicates that the larger array would show a further improvement in noise performance -- on the order of 25 carriers. A preliminary evaluation of the projected performance of the 400 x 400 array and a representative set of star sensor requirements indicates that the CID has excellent potential as a stellar tracking device.

Burke, H. K.↗
NASA NTRS1979

The charge injection device /CID/ as a stellar tracking sensor

A 128 x 128 element CID imager was operated in a simulated stellar trackling environment and evaluated for temporal and pattern noise and spectral response over a temperature range of -40 C to +25 C. The test devices were fabricated on long-lifetime bulk silicon material and utilized very thin upper-level polysilicon electrodes for enhanced spectral response. A standard microcomputer was used to generate all control signals and to collect and process performance data. The results of this program were used to predict the performance of a 400 x 400 CID array designed specifically for stellar-tracking.

Burke, H. K.↗
NASA NTRS1981

Charge injection device evaluation hardware

A microprocessor based system which provides maximum testing flexibility via software reconfiguration is described. This system has the capability to evaluate a charge injection device (CID) and to characterize its performance. The construction and operation of the CID offer advantages over the various CCD configurations available. These advantages include a less sophisticated manufacturing process, no images smearing during readout, high transfer efficiencies, and high resistance to blooming due to optical overload.

Source record↗
NASA NTRS1981

Infrared charge-injection-device array performance at low background

Low-background tests of a 1 x 32 Si:Bi charge-injection-device (CID) IR detector are carried out to evaluate its feasibility for space-based astronomical observations. Optimum performance is obtained at a temperature of 11 K. The sensitivity is found to compare well with that of discrete extrinsic silicon photoconductors. The measured sensitivity and the apparent absence of anomalous effects make extrinsic silicon CID arrays very promising for astronomical applications.

Mccreight, C. R.↗
NASA NTRS1984

Improved charge injection device and a focal plane interface electronics board for stellar tracking

An improved Charge Injection Device (CID) stellar tracking sensor and an operating sensor in a control/readout electronics board were developed. The sensor consists of a shift register scanned, 256x256 CID array organized for readout of 4x4 subarrays. The 4x4 subarrays can be positioned anywhere within the 256x256 array with a 2 pixel resolution. This allows continuous tracking of a number of stars simultaneously since nine pixels (3x3) centered on any star can always be read out. Organization and operation of this sensor and the improvements in design and semiconductor processing are described. A hermetic package incorporating an internal thermoelectric cooler assembled using low temperature solders was developed. The electronics board, which contains the sensor drivers, amplifiers, sample hold circuits, multiplexer, analog to digital converter, and the sensor temperature control circuits, is also described. Packaged sensors were evaluated for readout efficiency, spectral quantum efficiency, temporal noise, fixed pattern noise, and dark current. Eight sensors along with two tracker electronics boards were completed, evaluated, and delivered.

Michon, G. J.↗
NASA NTRS1984

Analysis of a transport fuselage section drop test

Transport fuselage section drop tests provided useful information about the crash behavior of metal aircraft in preparation for a full-scale Boeing 720 controlled impact demonstration (CID). The fuselage sections have also provided an operational test environment for the data acquisition system designed for the CID test, and data for analysis and correlation with the DYCAST nonlinear finite-element program. The correlation of the DYCAST section model predictions was quite good for the total fuselage crushing deflection (22 to 24 inches predicted versus 24 to 26 inches measured), floor deformation, and accelerations for the floor and fuselage. The DYCAST seat and occupant model was adequate to approximate dynamic loading to the floor, but a more sophisticated model would be required for good correlation with dummy accelerations. Although a full-section model using only finite elements for the subfloor was desirable, constraints of time and computer resources limited the finite-element subfloor model to a two-frame model. Results from the two-frame model indicate that DYCAST can provide excellent correlation with experimental crash behavior of fuselage structure with a minimum of empirical force-deflection data representing structure in the analytical model.

E. L. Fasanella↗
NASA NTRS1983

Scintillator-fiber charged particle track-imaging detector

A scintillator-fiber charged-particle track-imaging detector was developed using a bundle of square cross section plastic scintillator fiber optics, proximity focused onto an image intensified charge injection device (CID) camera. The tracks of charged particle penetrating into the scintillator fiber bundle are projected onto the CID camera and the imaging information is read out in video format. The detector was exposed to beams of 15 MeV protons and relativistic Neon, Manganese, and Gold nuclei and images of their tracks were obtained. Details of the detector technique, properties of the tracks obtained, and preliminary range measurements of 15 MeV protons stopping in the fiber bundle are presented.

Binns, W. R.↗
NASA NTRS1985

Charge-injection-device 2 x 64 element infrared array performance

Three 2 x 64 element Si:Bi accumulation-mode charge-injection-device (CID) arrays were tested at low and moderate background to evaluate their usefulness for space-based astronomical observations. Testing was conducted both in the laboratory and in ground-based telescope IR observations. The devices showed an average readout noise level below 200 equivalent electrons, a peak responsivity of 4 A/W, and a noise equivalent power of 3 x 10 to the -17th W/sq rt Hz. This sensitivity compares well with that of nonintegrating discrete extrinsic silicon photoconductors. The array well capacity was significantly smaller than predicted. The measured sensitivity makes extrinsic silicon CID arrays useful for certain astronomical applications. However, their readout efficiency and frequency response represent serious limitations in low-background applications.

Mckelvey, M. E.↗