ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Chemistry  (5,684)
  • AIRCRAFT PROPULSION AND POWER  (270)
  • COMMUNICATIONS AND RADAR  (237)
  • 1975-1979  (6,191)
  • 1977  (6,191)
Collection
Keywords
Publisher
Years
  • 1975-1979  (6,191)
Year
  • 1
    facet.materialart.
    Unknown
    Different approaches of spectral analysis (1977)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: Several approaches to the problem of the calculation of spectral power density of a random function from an estimate of the autocorrelation function were studied. A comparative study was presented of these different methods. The principles on which they are based and the hypothesis implied were pointed out. Some indications on the optimization of the length of the estimated correlation function was given. An example of application of the different methods discussed in this paper was included.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA-TM-75224
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 2
    facet.materialart.
    Unknown
    NASA teleconferencing pilot project - An evaluation of teleconferencing as a substitute for travel (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-08-28
    Description: NASA conducted a Pilot Project during 1975-1976 to determine the extent to which teleconferencing could replace travel to meetings. The network consisted of approximately 34 teleconference rooms and 50 fast facsimile machines, all interconnected on private lines to a master switchboard in Huntsville, Alabama. In addition, portable conference telephones augmented the voice network and experimental video conferences were attempted. Evaluations showed that the teleconferences saved travel costs approximating 21% of the travel budget at a communications cost of 3% of this budget.
    Keywords: COMMUNICATIONS AND RADAR
    Type: In: International Telemetering Conference; Oct 18, 1977 - Oct 20, 1977; Los Angeles, CA
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 3
    facet.materialart.
    Unknown
    New materials for high temperature turbines; ONERA's DS composites confronted with blade problems (1977)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: ONERA's refractory DS composites were cited as materials required for use in advanced aircraft turbines, operating at high temperatures. These materials were found to be reliable in the construction of turbine blades. Requirements for a blade material in aircraft turbines operating at higher temperatures were compared with the actual performance as found in COTAC DS composite testing. The structure and properties of the more fully developed 74 and 741 types were specified. High temperature structural stability, impact of thermal and mechanical fatigue, oxidation resistance and coating capability were thoroughly evaluated. The problem of cooling passages in DS eutectic blades is also outlined.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-75216 , High Temp. Probl. in Gas Turbine Eng.; 19-23 Sept. 1977; Ankara
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 4
    facet.materialart.
    Unknown
    High temperature corrosion-resistant protective coatings in stationary gas turbines (1977)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: Methods currently used to deposit protective coatings in gas turbines are reviewed, and the structure of the respective coatings is examined. The corrosion behavior of such coatings is discussed on the basis of experimental data. General trends in the preparation of protective coatings are noted.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-75181 , Tagung in Verbundwerkstoffe; Mar 28, 1974 - Mar 29, 1974; Constance; Germany
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 5
    facet.materialart.
    Unknown
    Analysis of economics of a TV broadcasting satellite for additional nationwide TV programs (1977)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: The influence of a TV broadcasting satellite, transmitting four additional TV networks was analyzed. It is assumed that the cost of the satellite systems will be financed by the cable TV system operators. The additional TV programs increase income by attracting additional subscribers. Two economic models were established: (1) each local network is regarded as an independent economic unit with individual fees (cost price model) and (2) all networks are part of one public cable TV company with uniform fees (uniform price model). Assumptions are made for penetration as a function of subscription rates. Main results of the study are: the installation of a TV broadcasting satellite improves the economics of CTV-networks in both models; the overall coverage achievable by the uniform price model is significantly higher than that achievable by the cost price model.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA-TM-75128 , BMFT-FB-T-76-5 , BMFT-NT-581
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 6
    facet.materialart.
    Unknown
    Aerodynamic investigation of an air-cooled axial-flow turbine. Part 2: Rotor blade tip-clearance effects on overall turbine performance and internal gas flow conditions: Experimental results and prediction methods (1977)
    In:  CASI
    Details
    Publication Date: 2019-08-27
    Description: Total turbine blade performance was investigated while changing the blade tip clearance in three ways. The internal flow at the moving blade outlet point was measured. Experimental results were compared with various theoretical methods. Increased blade clearance leads to decreased turbine efficiency.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-75138
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 7
    facet.materialart.
    Unknown
    Eight-bladed propeller design could bring back turboprop airplanes (1977)
    In:  CASI
    Details
    Publication Date: 2019-08-27
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: P77-10204 , NASA-NEWS-RELEASE-77-206
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 8
    facet.materialart.
    Unknown
    Protection of cooled blades of complex internal structure (1977)
    In:  CASI
    Details
    Publication Date: 2019-08-27
    Description: The problem of general protection of cooled blades of complex internal structure was solved by a method called SF technique which makes possible the protection of both external and internal surfaces, as well as those of the orifices of cooling air, whatever their diameter. The SF method is most often applied in the case of pack process, at controlled or high activity; it can be of use on previously uncoated parts, but also on pieces already coated by a thermochemical, chemical or PVD method. The respective thickness of external and internal coatings may be precisely predetermined, no parasitic particle being liable to remain inside the parts after application of the protecting treatment. Results obtained to date by application of this method are illustrated by the presentation and examination of a various selection of advanced turbo engines.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-75217 , AGARD-CP-229 , Conf. on High Temp. Probl. in Gas Turbine Engines; Sep 19, 1977 - Sep 23, 1977; Ankara
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 9
    facet.materialart.
    Unknown
    Effect of Flame Stabilizer Design on Performance and Exhaust Pollutants of a Two-Row Swirl-Can Combustor Operated to Near-Stoichiometric Conditions (1977)
    In:  CASI
    Details
    Publication Date: 2019-08-14
    Description: Emissions and performance characteristics were determined for two full annulus modular combustors operated to near stoichiometric fuel air ratios. The tests were conducted to obtain stoichiometric data at inlet air temperatures from 756 to 894 K and to determine the effects of a flat plate circular flame stabilizer with upstream fuel injection and a contraswirl flame stabilizer with downstream fuel injection. Levels of unburned hydrocarbons were below 0.50 gram per kilogram of fuel for both combustors and thus there was no detectable difference in the two methods of fuel injection. The contraswirl flame stabilizer did not produce the level of mixing obtained with a flat plate circular flame stabilizer. It did produce higher levels of oxides of nitrogen, which peaked at a fuel air ratio of 0.037. For the flat plate circular flame stabilizer, oxides of nitrogen emission levels were still increasing with fuel air ratio to the maximum tested value of 0.045.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-X-3495 , E-8317
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 10
    facet.materialart.
    Unknown
    Reducing secondary losses by blowing cold air in a turbine (1977)
    In:  CASI
    Details
    Publication Date: 2019-08-13
    Description: Local blowing on the profile suction side of the turbine guide wheel blades can be effective in preventing the propagation of secondary flows that is, the transport of casing and hub boundary layers by pressure gradients. Some preliminary results on how the blowing should be accomplished in order to influence the secondary flows in the desired manner are given. The effectiveness of blowing is demonstrated. Blowing is also seen to be more effective than using boundary layer slots as far as diminishing losses in the rim zones is concerned.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-75185 , PAPER-76-164 , DGLR Jahrestagung; Sep 14, 1976 - Sep 16, 1976; Munich
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 11
    facet.materialart.
    Unknown
    Effects of film injection on performance of a cooled turbine (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-27
    Description: Some of the most dramatic increases in the performance of turbojet and turbofan aircraft engines have been obtained as a result of increased thermodynamic cycle temperatures made possible by the use of film cooling techniques. The realization of the potential performance gains, however, is only possible if the quantity of cooling air and the aerodynamic mixing losses resulting from the injection of coolant in the form of film on the flowpath surfaces are minimized. Such a minimization requires a more complete understanding of the relationship between cooling and aerodynamics. A review is conducted of tests which have been conducted to determine the effects of coolant injection on turbine performance. The results obtained in the tests are compared with an analytical technique developed for predicting coolant injection effects. Particular attention is given to the effects of turbine cooling on overall cycle thermodynamic efficiency, taking into account incremental changes in turbine thermodynamic efficiency for various incremental changes in coolant flow rate.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Propulsion and Energetics Panel Meeting; Sept. 19-23, 1977; Ankara; Turkey
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 12
    facet.materialart.
    Unknown
    ATS-6 ascending: Near horizon measurements over water at 30 GHz (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The return of the ATS 6 satellite to a western longitude during the fall of 1976 presented a unique opportunity to perform low angle of elevation measurements at 30 GHz. For this purpose a receiver using a 1.5 m antenna was set up at Port Aransas, Texas, resulting in a propagation path entirely over water. The 30 GHz beacon was monitored daily for at least one hour from 8 September 1976 to 21 September 1976. During the time the elevation angle changed from 1.5 deg to 17.3 deg, the mean attenuation decreased from 20 dB to 2 dB and the standard deviation from over 6 dB to less than .2 dB. The deep fades at angles below 4 deg show significantly sharper nulls than peaks on a log scale. Spectra of the log amplitude fluctuations vary as the (-8/3) power of the spectral frequency in the limit. A flattening is noticeable at the low frequencies. A precipitation event at 8.5 deg elevation produced a 16 dB fade and significantly increased the variance.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA-CR-159966 , URSI Comm. of Open Symp. on Propagation in Nonionized Media; Apr 28, 1977 - May 06, 1977; LaBaule; France
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 13
    facet.materialart.
    Unknown
    Aircraft measurement of radio frequency noise at 121.5 MHz, 243MHz and 406MHz (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: An airborne survey measurement of terrestrial radio-frequency noise over U.S. metropolitan areas has been made at 121.5, 243 and 406 MHz with horizontal-polarization monopole antennas. Flights were at 25,000 feet altitude during the period from December 30, 1976 to January 8, 1977. Radio-noise measurements, expressed in equivalent antenna-noise temperature, indicate a steady-background noise temperature of 572,000 K, at 121.5 MHz, during daylight over New York City. This data is helpful in compiling radio-noise temperature maps; in turn useful for designing satellite-aided, emergency-distress search and rescue communication systems.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Symposium and Technical Exhibition; Jun 28, 1977 - Jun 30, 1977; Montreux; Switzerland
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 14
    facet.materialart.
    Unknown
    The proposed coding standard at GSFC (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: As part of the continuing effort to introduce standardization of spacecraft and ground equipment in satellite systems, NASA's Goddard Space Flight Center and other NASA facilities have supported the development of a set of standards for the use of error control coding in telemetry subsystems. These standards are intended to ensure compatibility between spacecraft and ground encoding equipment, while allowing sufficient flexibility to meet all anticipated mission requirements. The standards which have been developed to date cover the application of block codes in error detection and error correction modes, as well as short and long constraint length convolutional codes decoded via the Viterbi and sequential decoding algorithms, respectively. Included are detailed specifications of the codes, and their implementation. Current effort is directed toward the development of standards covering channels with burst noise characteristics, channels with feedback, and code concatenation.
    Keywords: COMMUNICATIONS AND RADAR
    Type: EASCON-77; Electronics and Aerospace Systems Convention; Sep 26, 1977 - Sep 28, 1977; Arlington, VA
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 15
    facet.materialart.
    Unknown
    Public Service Communication Satellite Program (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The proposed NASA Public Service Communication Satellite Program consists of four different activities designed to fulfill the needs of public service sector. These are: interaction with the users, experimentation with existing satellites, development of a limited capability satellite for the earliest possible launch, and initiation of an R&D program to develop the greatly increased capability that future systems will require. This paper will discuss NASA efforts in each of these areas.
    Keywords: COMMUNICATIONS AND RADAR
    Type: EASCON-77; Electronics and Aerospace Systems Convention; Sep 26, 1977 - Sep 28, 1977; Arlington, VA
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 16
    facet.materialart.
    Unknown
    State-of-the-art of turbofan engine noise control (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A description is presented of some of the recent advances in the technology of turbofan engine noise reduction, taking into account turbomachinery noise sources, new fans for low noise, fan and core noise suppression, and a new program for improving static noise testing of fans and engines. The problem of jet noise has been substantially reduced in connection with the lower jet velocities employed in the case of the high bypass turbofan engines. The dominant noise sources are now related to the turbomachinery with the fan stage, the compressor, and the turbine. Since the fan stage is the primary source of turbomachinery noise, it has been considered in a major part of the investigations designed to reduce turbofan engine noise.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: In: NOISE-CON 77; National Conference on Noise Control Engineering; Oct 17, 1977 - Oct 19, 1977; Hampton, VA
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 17
    facet.materialart.
    Unknown
    Effect of airstream velocity on mean drop diameters of water sprays produced by pressure and air atomizing nozzles (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A scanning radiometer was used to determine the effect of airstream velocity on the mean drop diameter of water sprays produced by pressure atomizing and air atomizing fuel nozzles used in previous combustion studies. Increasing airstream velocity from 23 to 53.4 meters per second reduced the Sauter mean diameter by approximately 50 percent with both types of fuel nozzles. The use of a sonic cup attached to the tip of an air assist nozzle reduced the Sauter mean diameter by approximately 40 percent. Test conditions included airstream velocities of 23 to 53.4 meters per second at 293 K and atmospheric pressure.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Winter Annual Meeting; Nov 27, 1977 - Dec 02, 1977; Atlanta, GA
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 18
    facet.materialart.
    Unknown
    Communication satellite services for special purpose users (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The present study identifies potential satellite services, examines the technology necessary for efficient implementation of these services, and determines minimum service cost versus user network size. The generic satellite services evaluated comprise TV and radio distribution (for retransmission), video teleconferencing (interactive), audio/facsimile teleconferencing (interactive), multiplexed data/voice (point-to-point), and satellite-supported land mobile. Satellite costs are based on extrapolations from ongoing commercial satellite programs. Production methods, new technology, and effect of production quantities on present and future production costs are examined to provide information on earth station equipment cost versus the variable 'buy'. Six different launch vehicles from a Delta 2914 to a dedicated Shuttle and three frequency bands and both broadcast (no eclipse capability) and fixed service satellites are considered to assess the effect of satellite size on cost and performance. It is assumed that the user pays only for his prorata share of the space segment costs.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Intelcom ''77 Symposium; Oct 09, 1977 - Oct 15, 1977; Atlanta, GA
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 19
    facet.materialart.
    Unknown
    Low cost Ku-band earth terminals for voice/data/facsimile (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A Ku-band satellite earth terminal capable of providing two way voice/facsimile teleconferencing, 128 Kbps data, telephone, and high-speed imagery services is proposed. Optimized terminal cost and configuration are presented as a function of FDMA and TDMA approaches to multiple access. The entire terminal from the antenna to microphones, speakers and facsimile equipment is considered. Component cost versus performance has been projected as a function of size of the procurement and predicted hardware innovations and production techniques through 1985. The lowest cost combinations of components has been determined in a computer optimization algorithm. The system requirements including terminal EIRP and G/T, satellite size, power per spacecraft transponder, satellite antenna characteristics, and link propagation outage were selected using a computerized system cost/performance optimization algorithm. System cost and terminal cost and performance requirements are presented as a function of the size of a nationwide U.S. network. Service costs are compared with typical conference travel costs to show the viability of the proposed terminal.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Intelcom ''77 Symposium; Oct 09, 1977 - Oct 15, 1977; Atlanta, GA
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 20
    facet.materialart.
    Unknown
    General aviation energy-conservation research programs at NASA-Lewis Research Center (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A review is presented of non-turbine general aviation engine programs underway at the NASA-Lewis Research Center in Cleveland, Ohio. The program encompasses conventional, lightweight diesel and rotary engines. Its three major thrusts are, in order of priority: (1) reduced SFCs; (2) improved fuels tolerance; and (3) reducing emissions. Current and planned future programs in such areas as lean operation, improved fuel management, advanced cooling techniques and advanced engine concepts, are described. These are expected to lay the technology base, by the mid to latter 1980s, for engines whose total fuel costs are as much as 30% lower than today's conventional engines.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Conference on Energy Conservation in General Aviation; Oct 10, 1977 - Oct 11, 1977; Kalamazoo, MI
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 21
    facet.materialart.
    Unknown
    Multiple-access channels without synchronization (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: This paper discusses models for multiple-access communications which take into account the fact that the channel users may not be able to synchronize their transmissions. It is shown that for a broad class of such channels, the capacity region is the same as it would be with user synchronization. Some open problems are discussed.
    Keywords: COMMUNICATIONS AND RADAR
    Type: International Conference on Communications; Jun 12, 1977 - Jun 15, 1977; Chicago, IL
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 22
    facet.materialart.
    Unknown
    Carrier synchronization techniques for unbalanced QPSK signals. I (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: This paper uses MAP estimation techniques to obtain carrier reconstruction circuits for unbalanced QPSK signals. In addition, the performance analysis of these circuits is carried out to the extent that a loop design can proceed. Numerical results are presented in order to demonstrate the utility of the theory developed. This signal design will be used in the development of the Tracking and Data Relay Satellite System (TDRSS) and the Navigation Satellite Timing and Ranging Global Positioning System (NAVSTAR GPS).
    Keywords: COMMUNICATIONS AND RADAR
    Type: International Conference on Communications; Jun 12, 1977 - Jun 15, 1977; Chicago, IL
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 23
    facet.materialart.
    Unknown
    Spectrally efficient modulation (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Spectrally efficient modulation, involving the maximization of the transmitted data rate through a specified bandwidth, may aid in alleviating the problem of spectral congestion in the electromagnetic spectrum. Attention is given to pulse-shaping and nonbinary modulation, and particularly to combined amplitude- and phase-modulation. Theoretical performance limits, such as Shannon's bound, are used to assess the effectiveness of the systems described. Consideration is also allotted to spectrally efficient modulation for terrestrial microwave systems, required to provide 1000 voice channels in the 4- and 6-GHz band.
    Keywords: COMMUNICATIONS AND RADAR
    Type: International Conference on Communications; Jun 12, 1977 - Jun 15, 1977; Chicago, IL
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 24
    facet.materialart.
    Unknown
    System design for the digitally implemented communications experiment /DICE/ (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Full-duplex digital television providing a teleconference capability is to be evaluated in an experimental program utilizing the Communications Technology Satellite. The digitally implemented communications experiment employs a QPSK modulator-demodulator capable of operation over a wide range of bit rates. In addition to simultaneous data transmission (used for digital high-speed facsimiles and remote computer terminals), voice transmission through four-to-one compression will be studied.
    Keywords: COMMUNICATIONS AND RADAR
    Type: International Conference on Communications; Jun 12, 1977 - Jun 15, 1977; Chicago, IL
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 25
    facet.materialart.
    Unknown
    Interaction of electromagnetic and acoustic waves in a stochastic atmosphere (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: This paper considers the interaction of electromagnetic and acoustic waves where a Radio Acoustic Sounding System (RASS) is operated in a stochastic environment characterized by turbulence, winds and mean-temperature gradients. It has been shown that for a RASS operating at acoustic frequencies below a few kilohertz propagating under typical atmospheric conditions, turbulence has little effect on the strength of the received radio signal scattered from the pulse at heights up to a few kilometers. This result implies that the received RF signal level (power) is primarily a function of sound intensity which decreases as x exp minus 2 where x is the altitude.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Union Radio Scientifique Internationale Open Symposium; Apr 28, 1977 - May 06, 1977; Loire-Atlantique; France
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 26
    facet.materialart.
    Unknown
    Rain depolarization and attenuation measurements at 11.7, 19.04, and 28.56 GHz - A description of the experiment and some preliminary results (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The considered investigation made use of the Communications Technology Satellite (CTS) downlink and the beacons carried by the Comstar satellites. The general behavior of rain attenuation and depolarization is illustrated with the aid of data from a storm which took place on July 15, 1976. The effect of the rain on the copolarized signal is indicated in a graph. Another graph shows the behavior of the cross-polarized signal component. Phase effects are also considered together with statistical curves for attenuation. The considered data from CTS indicate that, at least during summer convective storms, attenuation at 11.7 GHz is much more severe than anticipated. Attenuation may be a more serious impediment to dual polarized satellite links at this frequency than is depolarization.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Union Radio Scientifique Internationale Open Symposium; Apr 28, 1977 - May 06, 1977; Loire-Atlantique; France
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 27
    facet.materialart.
    Unknown
    Output feedback regulator design for jet engine control systems (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A multivariable control design procedure based on the output feedback regulator formulation is described and applied to an F100 turbofan engine model. Full order model dynamics, are incorporated in the example design. The effect of actuator dynamics on closed loop performance is investigated. Also, the importance of turbine inlet temperature as an element of the dynamic feedback is studied. Step responses are given to indicate the improvement in system performance with this control. Calculation times for all experiments are given in CPU seconds for comparison purposes.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: National Electronics Conference; Oct 13, 1977 - Oct 14, 1977; Chicago, IL
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 28
    facet.materialart.
    Unknown
    CTS /Hermes/ - United States experiments and operations summary (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The U.S. experiments conducted with the Communications Technology Satellite, a joint Canadian-U.S. venture launched in 1976, are discussed. The 14/12 GHz frequencies employed by the 200-W transmitter on board the satellite provide two-way television and voice communications. Applications of the satellite in the categories of health care, community services and education are considered; experiments have also made use of the special properties of the super-high frequency band (e.g. link characterization and digital communications). Time-sharing of the 14/12 GHz communication between the U.S. and Canada has functioned well.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Symposium on Hermes (Communications Technology Satellite): Its Performance and Applications; Nov 29, 1977 - Dec 01, 1977; Ottawa; Canada
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 29
    facet.materialart.
    Unknown
    A digitally implemented communications experiment utilizing the Hermes /CTS/ satellite (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Attention is given to an investigation being conducted by NASA-Lewis and Comsat Laboratories which uses the Hermes (CTS) satellite to explain digital link implementation and the advantages it provides over conventional analog systems. The experiment concentrates on developing several video, audio, and data digital communications techniques.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Symposium on Hermes (Communications Technology Satellite): Its Performance and Applications; Nov 29, 1977 - Dec 01, 1977; Ottawa; Canada
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 30
    facet.materialart.
    Unknown
    Utilization of NASA Lewis mobile terminals for the Hermes satellite (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The paper describes the portable earth terminal (PET) and the transportable earth terminal (TET) which enable two-way television and voice communication. Both terminals were developed by NASA and utilize the high power of the Hermes satellite. PET is a bus-type vehicle which has receiving equipment for full duplex color television and which can transmit programs originating in either the on-board PET studio or in nearby buildings. PET has a collapsible 2.4-m diameter parabolic antenna interfacing with a 500-watt 14-GHz wideband TV transmitter and a 12-GHz wideband TV receiver system. TET uses two parabolic reflector antennas, 3 m and 1.2 m in diameter, mounted on a flat trailer towed by a truck. TET can receive and relay color TV signals, and its narrowband transmitter can serve as a return audio link permitting a question-and-answer format. Also described are uplink and downlink performance characteristics, operation procedures, and field demonstrations which enabled personnel at several hospitals to participate in a distant medical conference.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Symposium on Hermes (Communications Technology Satellite): Its Performance and Applications; Nov 29, 1977 - Dec 01, 1977; Ottawa; Canada
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 31
    facet.materialart.
    Unknown
    Effectiveness of an inlet flow turbulence control device to simulate flight fan noise in an anechoic chamber (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A hemispherical inlet flow control device was tested on a 50.8 cm. (20-inch) diameter fan stage in the NASA-Lewis Anechoic Chamber. The control device used honeycomb and wire mesh to reduce turbulence intensities entering the fan. Far field acoustic power level results showed about a 5 dB reduction in blade passing tone and about 10 dB reduction in multiple pure tone sound power at 90% design fan speed with the inlet device in place. Hot film cross probes were inserted in the inlet to obtain data for two components of the turbulence at 65 and 90% design fan speed. Without the flow control device the axial intensities were below 1.0%, while the circumferential intensities were almost twice this value. The inflow control device significantly reduced the circumferential turbulence intensities and also reduced the axial length scale.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Meeting of the Acoustical Society of America; Dec 13, 1977 - Dec 16, 1977; Miami Beach, FL
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 32
    facet.materialart.
    Unknown
    Combustor fluctuating pressure measurements in-engine and in a component test facility - A preliminary comparison (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Combustor internal fluctuating pressure and far-field noise generated in a YF-102 turbofan engine are investigated; combustor internal measurements are also made in a duct-component test facility operating over a range of conditions encompassing those characteristic of the aircraft engine. Although directly measured spectra for the engine and the duct-component test facility show discrepancies, the results of coherence function, transfer function and phase relationship comparisons suggest that the internal dynamics of the combustor as an acoustic source may be preserved in a component test facility.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Meeting of the Acoustical Society of America; Dec 13, 1977 - Dec 16, 1977; Miami Beach, FL
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 33
    facet.materialart.
    Unknown
    An empirical model for inverted-velocity-profile jet noise prediction (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: It is known that the noise generated by inverted-velocity-profile coaxial (without center plug) and coannular (with center plug) nozzles should be modeled as the combined contributions of various source regions and noise generation mechanisms. In this paper, an empirical noise-prediction model is described which considers the noise generated by two jet-mixing regions and two potential regions of shock/turbulence interaction. Results calculated from the empirical model are compared with model-scale experimental data for static and simulated flight conditions. These comparisons are made for cases where both streams are subsonic, where the outer stream is supersonic with the inner stream subsonic, and where both streams are supersonic. The cases considered cover a range of inner-to-outer-stream area ratios and include both coaxial and coannular nozzles. It is shown that the model gives reasonable predictions of absolute noise spectra and even better predictions of incremental changes.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Meeting of the Acoustical Society of America; Dec 13, 1977 - Dec 16, 1977; Miami Beach, FL
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 34
    facet.materialart.
    Unknown
    Noise of deflectors used for flow attachment with STOL-OTW configurations (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Future STOL aircraft may utilize engine-over-the-wing (OTW) installations in which the exhaust nozzles are located above and separated from the upper surface of the wing. An external jet-flow deflector can be used with such installations to provide flow attachment to the wing/flap surfaces for lift augmentation. In the present work, the deflector noise in the flyover plane measured with several model-scale nozzle/deflector/wing configurations is examined. The deflector-associated noise is correlated in terms of velocity and geometry parameters. The data also indicate that the effective overall sound pressure level of the deflector-associated noise peaks in the forward quadrant near 40 deg from the inlet axis.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Meeting of the Acoustical Society of America; Dec 13, 1977 - Dec 16, 1977; Miami Beach, FL
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 35
    facet.materialart.
    Unknown
    Failure detection and correction for turbofan engines (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: In this paper, a failure detection and correction strategy for turbofan engines is discussed. This strategy allows continuing control of the engines in the event of a sensor failure. An extended Kalman filter is used to provide the best estimate of the state of the engine based on currently available sensor outputs. Should a sensor failure occur the control is based on the best estimate rather than the sensor output. The extended Kalman filter consists of essentially two parts, a nonlinear model of the engine and up-date logic which causes the model to track the actual engine. Details on the model and up-date logic are presented. To allow implementation, approximations are made to the feedback gain matrix which result in a single feedback matrix which is suitable for use over the entire flight envelope. The effect of these approximations on stability and response is discussed. Results from a detailed nonlinear simulation indicate that good control can be maintained even under multiple failures.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Joint Automatic Control Conference; Jun 22, 1977 - Jun 24, 1977; San Francisco, CA; US
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 36
    facet.materialart.
    Unknown
    Design of turbofan engine controls using output feedback regulator theory (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A multivariable control design procedure based on output feedback regulator (OFR) theory is applied to the F100 turbofan engine. Results for the OFR design are compared to a design based on linear quadratic regulator (LQR) theory. This LQR design was obtained as part of the F100 Multivariable Control Synthesis (MVCS) program. In the MVCS program the LQR feedback control was designed in a reduced dimension state space and then applied to the original system. However, the OFR feedback control is designed in the full order state space and thus eliminates any need for model reduction techniques. Using the performance measure and control structure of the MVCS program LQR design, an equivalent OFR feedback control is obtained. The flexibility of the OFR as a control design procedure is demonstrated and differing feedback control structures are evaluated.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Joint Automatic Control Conference; Jun 22, 1977 - Jun 24, 1977; San Francisco, CA
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 37
    facet.materialart.
    Unknown
    Optimal controls for an advanced turbofan engine (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Linear optimal control theory is applied to the control synthesis of a high bypass ratio, variable pitch, turbofan engine. The basic control philosophy is to use only a low order dynamic model of the plant coupled with the concept of integral-output states so as to maintain control simplicity yet guarantee integral control of thrust, turbine temperature and other important engine outputs. Linear simulation results indicate that the control system developed provides rapid control of small thrust perturbations and quickly eliminates the effect of unmodelled thrust and temperature disturbances. Large thrust accelerations are obtained in about one half second while the control maintains negligible overshoot in temperature and stall margins.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Joint Automatic Control Conference; Jun 22, 1977 - Jun 24, 1977; San Francisco, CA
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 38
    facet.materialart.
    Unknown
    The application of the Routh approximation method to turbofan engine models (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The Routh approximation technique is applied in the frequency domain to a 16th order state variable turbofan engine model. The results obtained motivate the extension of the frequency domain formulation of the Routh method to the time domain to handle the state variable formulation directly. The time domain formulation is derived and a new characterization, which specifies all possible Routh similarity transformations, is given. This characterization is computed by the solution of two eigenvalue-eigenvector problems. The application of the time domain Routh technique to the state variable engine model is described and some results are given. Additional computational problems are discussed including an optimization procedure which can improve the approximation accuracy by taking advantage of the transformation characterization.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Joint Automatic Control Conference; Jun 22, 1977 - Jun 24, 1977; San Francisco, CA
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 39
    facet.materialart.
    Unknown
    Minimum-time acceleration of aircraft turbofan engines (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Minimum-time accelerations of the F100 turbofan engine are presented. A piecewise-linear engine model, having three state variables and four control variables, is used to obtain the minimum-time solutions. The linear model which applies at a given time in the trajectory is determined by calculating a normalized 'distance' from the current state to the equilibrium state associated with each linear model. The linear model associated with the closest equilibrium point is then used. The control histories for the minimum-time solutions are used as input to a nonlinear simulation of the F100 engine to verify the accuracy of the piecewise-linear solutions.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Joint Automatic Control Conference; Jun 22, 1977 - Jun 24, 1977; San Francisco, CA
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 40
    facet.materialart.
    Unknown
    Frequency domain compensation of a DYNGEN turbofan engine model (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Following Rosenbrock's ideas regarding the advantages of dominance in linear multivariable control systems, a new graphical technique is used for the design of compensators that achieve dominance. The technique is illustrated with an application to the problem of designing compensators for a linear turbofan-engine model. The resulting design is put into perspective by examining it in the light of two other multivariable frequency-domain methods. One, MacFarlane's method of characteristic loci, is used to realize a final design for stability and low interaction. The other is a direct technique based upon the algebraic expansion of the determinant of the return difference in terms of it's elements. Results from simulations carried out on the NASA DYNGEN software are included.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Joint Automatic Control Conference; Jun 22, 1977 - Jun 24, 1977; San Francisco, CA
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 41
    facet.materialart.
    Unknown
    Preliminary QCSEE program - Test results (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Preliminary results are reported for the Quiet Clean Short-haul Experimental Engine (QCSEE) program initiated by NASA in 1974 to develop propulsion system technology suitable for powered-lift short-range commercial aircraft. The QCSEE technology also has applications to the proposed U.S. Navy V/STOL aircraft. Emphasis in the QCSEE program is placed on developing engines with low noise characteristics; in addition, the power plants are required to conform to EPA 1979 pollutant emissions standards. Thrust performance, fan design, and thrust/weight ratio are discussed for both the over-the-wing and under-the-wing engine configurations under study.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: SAE PAPER 771008 , Aerospace Meeting; Nov 14, 1977 - Nov 17, 1977; Los Angeles, CA
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 42
    facet.materialart.
    Unknown
    A compendium of millimeter wave propagation studies performed by NASA (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Key millimeter wave propagation experiments and analytical results were summarized. The experiments were performed with the Ats-5, Ats-6 and Comstar satellites, radars, radiometers and rain gage networks. Analytic models were developed for extrapolation of experimental results to frequencies, locations, and communications systems.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA-CR-156781
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 43
    facet.materialart.
    Unknown
    CTS attenuation and cross-polarization measurements at 11.7 GHz (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The results of data obtained 80 days preceding the solar eclipse shutdown of the CTS 11.7 GHz righthand circularly polarized beacon transmitter are presented. Attenuation and cross polarization isolation were measured. It was determined that depolarization presents a serious limitation to satellite system reliability when frequency reuse by polarization diversity is employed. A 27 db isolation margin would reduce reliability below 99.95%. For the same percentage the required fade margin was below 3 db.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA-CR-156771
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 44
    facet.materialart.
    Unknown
    Design and demonstration of an advanced data collection/position location system (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The final report on a breadboard evaluation and demonstration program is reported concerning the applicability of MSK modulation and chirp-z transformer technology in Advanced Data Collection/Position Location (ADC/PL) systems. The program effort consisted of three phases - design, testing, and evaluation. Section 2 describes the breadboard hardware built during the design phase of the program, Section 3 describes the tests conducted on the breadboard and the results of the tests, and Section 4 presents a brief analysis and summary of the findings of the breadboard tests and develops a sample ADC/PL system which incorporates both MSK modulation and a chirp-z transformer.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA-CR-156748
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 45
    facet.materialart.
    Unknown
    Analysis of synthetic aperture radar imagery (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Some problems faced in applications of radar measurements in hydrology are: (1) adequate calibration of the radar systems and direct digital data will be required in order that repeatable data can be acquired for hydrologic applications; (2) quantitative hydrologic research on a large scale will be prohibitive with aircraft mounted synthetic aperture radar systems due to the system geometry; (3) spacecraft platforms appear to be the best platforms for radar systems when conducting research over watersheds larger than a few square kilometers; (4) experimental radar systems should be designed to avoid use of radomes; and (5) cross polarized X and L band data seem to discriminate between good and poor hydrologic cover better than like polarized data.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA-CR-156743 , RSC-3359-2
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 46
    facet.materialart.
    Unknown
    High temperature environmental effects on metals (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The gas turbine engine was used as an example to predict high temperature environmental attack on metals. Environmental attack in a gas turbine engine derives from high temperature, combustion products of the air and fuel burned, and impurities. Of all the modes of attack associated with impurity effects, hot corrosion was the most complicated mechanistically. Solutions to the hot corrosion problem were sought semi-empirically in: (1) improved alloys or ceramics; (2) protective surface coating; (3) use of additives to the engine environment; and (4) air/fuel cleanup to eliminate harmful impurities.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-73878 , Sagamore Army Materials Res., Conf. Risk and Failure Analysis for Reliability; Aug 22, 1977 - Aug 26, 1977; Bolton Landing, NY; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 47
    facet.materialart.
    Unknown
    Preliminary QCSEE program test results (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The QCSEE (Quiet, Clean, Short-Haul Experimental Engine) program has entered the engine test phase. Overall design and advanced technology incorporated into the two engines in the program were described. In addition, preliminary engine test results are presented and compared to the technical requirements the engines were designed to meet.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-73732 , 1977 Aerospace Meeting; Nov 14, 1977 - Nov 17, 1977; Los Angeles
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 48
    facet.materialart.
    Unknown
    General aviation energy-conservation research programs at NASA-Lewis Research Center (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The major thrust of NASA's nonturbine general aviation engine programs is directed toward (1) reduced specific fuel consumption, (2) improved fuel tolerance; and (3) emission reduction. Current and planned future programs in such areas as lean operation, improved fuel management, advanced cooling techniques and advanced engine concepts, are described. These are expected to lay the technology base, by the mid to latter 1980's, for engines whose total fuel costs are as much as 30% lower than today's conventional engines.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-73884 , Conf. on Energy Conserv. in Gen. Aviation; Oct 10, 1977 - Oct 11, 1977; Kalamazoo, MI; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 49
    facet.materialart.
    Unknown
    Flight-Effects on Predicted Fan Fly-By Noise (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The impact on PNLT (Perceived Noise Level, Tone corrected) and Fly-by EPNL (Effective Perceived Noise Level) when forward motion reduces the noise generated by the bypass fan of an aircraft engine was studied. Calculated noise spectra for a typical subsonic tip speed fan designed for blade passage frequency (BPF) tone cutoff were translated in frequency by systematically varying the BPF from 0.5 to 8 kHz. Two cases of predicted flight-effects on fan source noises were considered: reduced BPF tone level of 8 db and reduced broadband noise level of about 2 db in addition to reduced tone level. The maximum reduction in PNLT of the noise as emitted from the fan occurred when the BPF was at 4 kHz where the reductions were 7.4 and 10.0 db. The maximum reduction in EPNL of the noise as received during a 500-foot altitude fly-by occurred when the BPF was at 2.5 kHz where the reductions were 5.0 and 7.8 db.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-73798 , Meeting of the Acoustical Soc. of Am.; Dec 13, 1977 - Dec 16, 1977; Miami, FL; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 50
    facet.materialart.
    Unknown
    Aircraft Engine Emissions (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A conference on a aircraft engine emissions was held to present the results of recent and current work. Such diverse areas as components, controls, energy efficient engine designs, and noise and pollution reduction are discussed.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CP-2021 , E-9262 , May 18, 1977 - May 19, 1977; Cleveland
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 51
    facet.materialart.
    Unknown
    Evaluation of an F100 multivariable control using a real-time engine simulation (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A multivariable control design for the F100 turbofan engine was evaluated, as part of the F100 multivariable control synthesis (MVCS) program. The evaluation utilized a real-time, hybrid computer simulation of the engine and a digital computer implementation of the control. Significant results of the evaluation are presented and recommendations concerning future engine testing of the control are made.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-X-73648 , E-9155 , Propulsion Conf.; Jul 11, 1977 - Jul 13, 1977; Orlando, FL; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 52
    facet.materialart.
    Unknown
    An Assessment of Technology for Turbojet Engine Rotor Failures (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Design considerations, objectives, and approaches used in containing rotor burst debris are discussed. Methods are given for determining the fracture resistance of various materials used in providing lightweight shielding from fragment impact.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CP-2017 , E-8305 , Mar 29, 1977 - Mar 31, 1977; Cambridge, MA; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 53
    facet.materialart.
    Unknown
    The jet engine design that can drastically reduce oxides of nitrogen (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The NOx pollution problem of hydrogen fueled turbojets and supersonic combustion ramjets (scramjets) was investigated to determine means of substantially alleviating the problem. Since the NOx reaction rates are much slower than the energy producing reactions, the NOx production depends mainly on the maximum local temperatures in the combustor and the NOx concentration is far from equilibrium at the end of a typical combustor (L approximately 1 ft). In diffusion flames, as used in present turbojets and scramjets combustor designs, the maximum local temperature occurs at the flame and is equal to the stoichiometric value. Whereas, in the heat conduction flames, wherein the flame propagates due to a heat conduction process away from the flame to the cooler oncoming premixed unburnt gases, the maximum temperature is lower than in the diffusion flame. Hence the corresponding pollution index is also lower.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 74-160 , Selected Papers on Advanced Design of Air Vehicles; p 79-88|AIAA Aerospace Sci. Meeting; Jan 30, 1974 - Feb 01, 1974; Washington, DC; United States
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 54
    facet.materialart.
    Unknown
    Acoustic performance of inlet multiple-pure-tone suppressors installed on NASA Quiet Engine 'C' (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The purpose of the experimental program reported herein was to define the length of multiple pure tone (MPT) treatment required to reasonably suppress the MPT's produced by a supersonic tip speed fan and also determine what other suppression, broadband, and blade passing frequency (BPF), might be accomplished. The experimental results are presented in terms of both far-field and duct acoustic data. Front quadrant sound power level reduction in the far field is shown to agree with duct measurements over the range of treatment lengths. Detailed one-third octave and narrow band spectra at the maximum forward noise angle are presented. Some detailed analyses of one-third-octave band amplitudes are shown as a function of far-field angle. An approximate spinning mode duct propagation analysis is then introduced which predicts the acoustic suppression by the treatment on the multiple pure tones.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 77-1333 , Aeroacoustics Conference; Oct 03, 1977 - Oct 05, 1977; Atlanta, GA
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 55
    facet.materialart.
    Unknown
    Coherence between internal and external noise generated by gas turbine combustors (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Experiments and analysis on a gas turbine combustor unit are reported with a view in mind to separate propagated acoustic power from non-propagating 'pseudo-sound'. Analytically, it is suggested that a transition frequency will exist below which the interior pressure fluctuations are non-propagating, whereas above this frequency, of the order of 100 Hz, the noise is dominated by propagating acoustic waves. Coherence measurements are reported which show this concept to be borne out experimentally. Coherence between interior and exterior microphones is measured over a wide range of experimental conditions for a gas turbine combustor exhausting directly to the atmosphere. The purpose is to show that below a certain frequency, measurements of interior noise are not indicative of combustion noise ultimately propagating from an engine.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 77-20 , Aerospace Sciences Meeting; Jan 24, 1977 - Jan 26, 1977; Los Angeles, CA
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 56
    facet.materialart.
    Unknown
    Electromagnetic plasma wave emissions from the auroral field lines (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The most important types of auroral radio emissions are reviewed, both from a historical perspective as well as considering the latest results. Particular emphasis is placed on four types of electromagnetic emissions which are directly associated with the plasma on the auroral field lines. These emissions are (1) auroral hiss, (2) saucers, (3) ELF noise bands, and (4) auroral kilometric radiation. Ray tracing and radio direction finding measurements indicate that both the auroral hiss and auroral kilometric radiation are generated along the auroral field lines relatively close to the earth, at radial distances from about 2.5 to 5 R sub e. For the auroral hiss the favored mechanism appears to be amplified Cerenkov radiation. For the auroral kilometric radiation several mechanisms have been proposed, usually involving the intermediate generation of electrostatic waves by the precipitating electrons.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA-CR-155172 , U-OF-IOWA-77-36 , Gen. Sci. Assembly of the Intern. Assoc. of Geomagnetism and Aeronomy; Jan 01, 1977; Seattle
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 57
    facet.materialart.
    Unknown
    Communication system analysis for manned space flight (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: One- and two-dimensional adaptive delta modulator (ADM) algorithms are discussed and compared. Results are shown for bit rates of two bits/pixel, one bit/pixel and 0.5 bits/pixel. Pictures showing the difference between the encoded-decoded pictures and the original pictures are presented. The effect of channel errors on the reconstructed picture is illustrated. A two-dimensional ADM using interframe encoding is also presented. This system operates at the rate of two bits/pixel and produces excellent quality pictures when there is little motion. The effect of large amounts of motion on the reconstructed picture is described.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA-CR-151508
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 58
    facet.materialart.
    Unknown
    State-of-the-art of turbofan engine noise control (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The technology of turbofan engine noise reduction is surveyed. Specific topics discussed include: (1) new fans for low noise; (2) fan and core noise suppression; (3) turbomachinery noise sources; and (4) a new program for improving static noise testing of fans and engines.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-73734 , E-9254 , NOISE-CON 77; Oct 17, 1977 - Oct 19, 1977; Hampton, VA; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 59
    facet.materialart.
    Unknown
    Measurement of far field combustion noise from a turbofan engine using coherence functions (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Coherence measurements between fluctuating pressure in the combustor of a YF-102 turbofan engine and far-field acoustic pressure were made. The results indicated that a coherent relationship between the combustor pressure and far-field existed only at frequencies below 250 Hz, with the peak occurring near 125 Hz. The coherence functions and the far-field spectra were used to compute the combustor-associated far-field noise in terms of spectra, directivity, and acoustic power, over a range of engine operating conditions. The acoustic results so measured were compared with results obtained by conventional methods, as well as with various semiempirical predictions schemes. Examination of the directivity patterns indicated a peak in the combustion noise near 120 deg (relative to the inlet axis).
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-73748 , E-9320 , AIAA PAPER 77-1277 , Aeroacoustics Conf.; Oct 03, 1977 - Oct 05, 1977; Atlanta
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 60
    facet.materialart.
    Unknown
    Steady-state unbalance response of a three-disk flexible rotor on flexible, damped supports (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Experimental data are presented for the unbalance response of a flexible, ball bearing supported rotor to speeds above the third lateral bending critical. Values of squeeze film damping coefficients obtained from measured data are compared to theoretical values obtained from short bearing approximation over a frequency range from 5000 to 31 000 cycles/min. Experimental response for an undamped rotor is compared to that of one having oil squeeze film dampers at the bearings. Unbalance applied varied from 0.62 to 15.1 gm-cm.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-X-73666 , E-9091-1 , Vibrations Conf.; Sep 26, 1977 - Sep 29, 1977; Chicago
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 61
    facet.materialart.
    Unknown
    Multimodal far-field acoustic radiation pattern: An approximate equation (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The far-field sound radiation theory for a circular duct was studied for both single mode and multimodal inputs. The investigation was intended to develop a method to determine the acoustic power produced by turbofans as a function of mode cut-off ratio. With reasonable simplifying assumptions the single mode radiation pattern was shown to be reducible to a function of mode cut-off ratio only. With modal cut-off ratio as the dominant variable, multimodal radiation patterns can be reduced to a simple explicit expression. This approximate expression provides excellent agreement with an exact calculation of the sound radiation pattern using equal acoustic power per mode.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-73721 , Aeroacoustics Conf.; Oct 03, 1977 - Oct 05, 1977; Atlanta
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 62
    facet.materialart.
    Unknown
    Output feedback regulator design for jet engine control systems (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A multivariable control design procedure based on the output feedback regulator formulation is described and applied to turbofan engine model. Full order model dynamics, were incorporated in the example design. The effect of actuator dynamics on closed loop performance was investigaged. Also, the importance of turbine inlet temperature as an element of the dynamic feedback was studied. Step responses were given to indicate the improvement in system performance with this control. Calculation times for all experiments are given in CPU seconds for comparison purposes.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-73776 , Intern. Forum on Alternatives for Linear Multivariable Control; Oct 13, 1977 - Oct 14, 1977; Chicago
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 63
    facet.materialart.
    Unknown
    Progress in advanced high temperature turbine materials, coatings, and technology (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Material categories as well as coatings and recent turbine cooling developments are reviewed. Current state of the art is identified, and as assessment, when appropriate, of progress, problems, and future directions is provided.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-X-73628 , Panel on Propulsion and Energetics; Sep 19, 1977 - Sep 23, 1977; Ankara
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 64
    facet.materialart.
    Unknown
    Solid state Ku-band spacecraft transmitters (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A transmitter is considered that consists of GaAs IMPATT and Read diodes operating in a microstrip circuit environment to provide amplification with a minimum of 63 db small signal gain and a minimum compressed gain at 5 W output of 57 db. Reported are Schottky-Read diode design and fabrication, microstrip and circulator optimization, preamplifier development, power amplifier development, dc-to-dc converter design, and integration of the breadboard transmitter modules. A four-stage power amplifier in cascade with a three-stage preamplifier had an overall gain of 56.5 db at 13.5 GHz with a power output of 4.5 W. A single-stage Read amplifier delivered 5.9 W with 4 db gain at 22% efficiency.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA-CR-152590 , TI-08-77-11
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 65
    facet.materialart.
    Unknown
    Advanced turboprop technology development (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The efficiency of high-speed turboprop propulsion systems is considered with emphasis on fuel savings. Specific topics discussed include: (1) high efficiency and low noise of propeller design; (2) fuselage noise attenuation; (3) propeller and gear box maintenance; and (4) engine-airframe integration.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-73729 , E-9290 , Aircraft Systems and Technol. Meeting; Aug 22, 1977 - Aug 24, 1977; Seattle
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 66
    facet.materialart.
    Unknown
    Design of turbofan engine controls using output feedback regulator theory (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A multivariable control design procedure based on output feedback regulator (OFR) theory is applied to the F100 turbofan engine. Results for the OFR design are compared to a design based on linear quadratic regulator (LQR) theory. The OFR feedback control is designed in the full order state space and thus eliminates any need for model reduction techniques. Using the performance measure and control structure of the LQR design, an equivalent OFR feedback control is obtained. The flexibility of the OFR as a control design procedure is demonstrated, and differing feedback control structures are evaluated.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-X-73622 , E-9113 , Joint Automatic Control Conf.; Jun 22, 1977 - Jun 24, 1977; San Francisco
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 67
    facet.materialart.
    Unknown
    Final report on technical work accomplished under contract NASw-2953 (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A report is given on the technical work accomplished in the area of plasma physics. The subjects covered are: (1) oblique whistler instabilities, (2) current-limited electron beam injection, (3) three-dimensional ion sound turbulence, (4) theoretical aspects of sounder antenna operation and (5) whistler modes in bow shock structures.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA-CR-153294 , TRW-29697-6002-RU-00
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 68
    facet.materialart.
    Unknown
    Research in millimeter wave techniques (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The following is investigated; (1) the design of a 183 GHz single ended fundamental mixer to serve as a back up mixer to the subharmonic mixer for airborne applications, (2) attainment of 6 db single sideband conversion loss with the 6 GHz subharmonic mixer model, together with initial tests to determine the feasibility of pumping the mixer at w sub s/4, (3) additional ground based radiometric measurements, and (4) derivation of equations for power transmission of wire grid interferometers, and initial tests to verify these equations.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA-CR-156762 , SATR-6
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 69
    facet.materialart.
    Unknown
    A depolarization and attenuation experiment using the CTS satellite (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Rain attenuation and depolarization data collected on the communications technology satellite 11.7 GHz downlink, and changes made in equipment following rain leak damage to the parametric amplifier are discussed. A 15 GHz radar system is described.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA-CR-152535 , QTPR-1
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 70
    facet.materialart.
    Unknown
    The application of the Routh approximation method to turbofan engine models (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The Routh approximation technique is applied in the frequency domain to a 16th order state variable turbofan engine model. The results obtained motivate the extension of the frequency domain formulation of the Routh method to the time domain to handle the state variable formulation directly. The time domain formulation is derived, and a characterization, which specifies all possible Routh similarity transformations, is given. The characterization is computed by the solution of two eigenvalue eigenvector problems. The application of the time domain Routh technique to the state variable engine model is described, and some results are given.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-X-73623 , E-9114 , Joint Autom. Control Conf.; Jun 22, 1977 - Jun 24, 1977; San Francisco
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 71
    facet.materialart.
    Unknown
    NASA Quiet Clean General Aviation Turbofan (QCGAT) program status (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The suitability of large engine technology to reduce noise, emissions, and fuel consumption of small turbine engines and develop new technology where required is determined. The design, fabrication, assembly, test, and delivery of the experimental engines to NASA are discussed.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-X-73564 , E-9008 , Intern. Gas Turbine Conf.; Mar 27, 1977 - Mar 31, 1977; Philadelphia, PA; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 72
    facet.materialart.
    Unknown
    Aircraft measurement of radio frequency noise at 121.5 MHz, 243 MHz and 406 MHz (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: An airborne survey measurement of terrestrial radio-frequency noise over U.S. metropolitan areas was carried out at 121.5, 243 and 406 MHz with horizontal-polarization monopole antennas. Flights were at 25,000 feet altitude. Radio-noise measurements, expressed in equivalent antenna-noise temperature, indicate a steady-background noise temperature of 572,000 K, at 121.5 MHz, during daylight over New York City. This data is helpful in compiling radio-noise temperature maps; in turn useful for designing satellite-aided, emergency-distress search and rescue communication systems.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA-TM-X-71283 , X-952-77-11 , Symp. and Technical Exhibition on Electromagnetic Compatibility; Jun 28, 1977 - Jun 30, 1977; Montreux; Switzerland
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 73
    facet.materialart.
    Unknown
    A depolarization and attenuation experiment using the CTS satellite. Volume 2: Data (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: An experiment for measuring precipitation attenuation and depolarization on the CTS 11.7 GHz downlink is described.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA-CR-152482
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 74
    facet.materialart.
    Unknown
    Effect of endwall cooling on secondary flows in turbine stator vanes (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The effect of endwall cooling on the secondary flow behavior and the aerodynamic performance of a core turbine stator vane was determined. The investigation was conducted in a cold-air, full-annular cascade, where three-dimensional effects were obtained. Two endwall cooling configurations were tested. In the first configuration, the cooling holes were oriented so that the coolant was injected in line with the inviscid streamline direction. In the second configuration, the coolant was injected at an angle of 15 deg to the inviscid streamline direction and oriented towards the vane pressure stator. In both cases the stator vanes were solid and uncooled so that the effect of endwall cooling was obtained directly. Total-pressure surveys were taken downstream of the stator vanes over a range of cooling flows at the design, mean-radius, critical velocity ratio of 0.778. Changes in the total-pressure contours downstream of the vanes were used to obtain the effect of endwall cooling on the secondary flows in the stator.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-X-73568 , AGARD 49th Propulsion and Energetics Panel Conf.; Mar 28, 1977 - Apr 04, 1977; The Hague
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 75
    facet.materialart.
    Unknown
    Core noise measurements on a YF-102 turbofan engine (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Core noise from a YF-102 high bypass ratio turbofan engine was investigated through the use of simultaneous measurements of internal fluctuating pressures and far field noise. Acoustic waveguide probes, located in the engine at the compressor exit, in the combustor, at the turbine exit, and in the core nozzle, were employed to measure internal fluctuating pressures. Spectra showed that the internal signals were free of tones, except at high frequency where machinery noise was present. Data obtained over a wide range of engine conditions suggest that below 60% of maximum fan speed the low frequency core noise contributes significantly to the far field noise.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-X-73587 , E-9050 , Aerospace Sci. Meeting; Jan 24, 1977 - Jan 26, 1977; Los Angeles
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 76
    facet.materialart.
    Unknown
    Repeater in the sky (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The Public Service Communications Satellite (PSCS) program is intended to develop and demonstrate a space system aimed at stimulating future commercial markets in fixed and mobile applications. The services are envisioned for rural areas, regions beyond access to terrestrial systems, or for continuous cross-country applications. The system incorporates a UHF repeater for mobile voice and data experiments; 8 MHz of spectrum is specified for serving 70 channels. This paper describes the PSCS program and discusses some demonstration experiments. A future concept based on large structure multibeam antennas is also discussed.
    Keywords: COMMUNICATIONS AND RADAR
    Type: National Electronics Conference; Oct 10, 1977 - Oct 12, 1977; Chicago, IL
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 77
    facet.materialart.
    Unknown
    Carrier synchronization techniques for unbalanced QPSK signals. II (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: This paper develops a theory for assessing the tracking performance and designing carrier synchronization loops which are to be matched to an unbalanced QPSK signal design. It is assumed that the power split and the I and Q channel data rates are arbitrary. Bit synchronization is assumed to be unavailable for both carrier reconstruction techniques which have been suggested via MAP estimation theory. Numerical results are presented.
    Keywords: COMMUNICATIONS AND RADAR
    Type: In: NTC ''77; National Telecommunications Conference; Dec 05, 1977 - Dec 07, 1977; Los Angeles, CA
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 78
    facet.materialart.
    Unknown
    Bit timing with pulse distortion and intersymbol interference (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Pulse distortion and intersymbol interference due to insufficient filtering in PCM and PSK channels cause performance degradation in terms of both bit error probabilities and timing errors. This paper reports the results of a study analyzing these effects on bit timing subsystems. Consideration is given to both the filter-rectifier and transition tracking type of timing subsystem. Although both these systems perform similarly in high SNR and ideal pulse models, pulse distortion and intersymbol affects each differently. The primary effects in both systems is to cause the presence of an irreducible mean squared timing error due to the intersymbol which limits the ultimate performance. Design procedures to minimize the anomalies of both systems are presented, and indicate modifications of the standard timing subsystems. It is found that specific design directions depend on whether the intersymbol or the receiver noise tends to dominate.
    Keywords: COMMUNICATIONS AND RADAR
    Type: In: NTC ''77; National Telecommunications Conference; Dec 05, 1977 - Dec 07, 1977; Los Angeles, CA
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 79
    facet.materialart.
    Unknown
    Non-parametric PCM to ADM conversion (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: An all-digital technique to convert pulse code modulated (PCM) signals into adaptive delta modulation (ADM) format is presented. The converter developed is shown to be independent of the statistical parameters of the encoded signal and can be constructed with only standard digital hardware. The structure of the converter is simple enough to be fabricated on a large scale integrated circuit where the advantages of reliability and cost can be optimized. A concise evaluation of this PCM to ADM translation technique is presented and several converters are simulated on a digital computer. A family of performance curves is given which displays the signal-to-noise ratio for sinusoidal test signals subjected to the conversion process, as a function of input signal power for several ratios of ADM rate to Nyquist rate.
    Keywords: COMMUNICATIONS AND RADAR
    Type: In: NTC ''77; National Telecommunications Conference; Dec 05, 1977 - Dec 07, 1977; Los Angeles, CA
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 80
    facet.materialart.
    Unknown
    Minimax decoding of cyclic block codes (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A minimax decoding algorithm utilizing soft bit detection of an (n,k) cyclic block code is described which will permit the correction of up to n-k bit errors interspersed at random locations throughout the block. The decoding solution consists of: (1) identifying the ordered soft bit set and, (2) finding the minimum order solution to the resulting syndrome equations where the nonzero error vector components are constrained to be a subset of the soft bit set. An efficient implementation of the decoding operation is described. In essence, this algorithm focuses the correction capability of the code on those bit positions which have the lowest a posteriori probabilities of correct detection.
    Keywords: COMMUNICATIONS AND RADAR
    Type: In: NTC ''77; National Telecommunications Conference; Dec 05, 1977 - Dec 07, 1977; Los Angeles, CA
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 81
    facet.materialart.
    Unknown
    On signal design by the R/0/ criterion for non-white Gaussian noise channels (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The use of the cut-off rate criterion for modulation system design is investigated for channels with non-white Gaussian noise. A signal space representation of the waveform channel is developed, and the cut-off rate for vector channels with additive non-white Gaussian noise and unquantized demodulation is derived. When the signal input to the channel is a continuous random vector, maximization of the cut-off rate with constrained average signal energy leads to a water-filling interpretation of optimal energy distribution in signal space. The necessary condition for a finite signal set to maximize the cut-off rate with constrained energy and an equally likely probability assignment of signal vectors is presented, and an algorithm is outlined for numerically computing the optimum signal set. As an example, the rectangular signal set which has the water-filling average energy distribution and the optimum rectangular set are compared.
    Keywords: COMMUNICATIONS AND RADAR
    Type: In: NTC ''77; National Telecommunications Conference; Dec 05, 1977 - Dec 07, 1977; Los Angeles, CA
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 82
    facet.materialart.
    Unknown
    Comparison of convolutional and block code performance on the Rician channel (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The paper is concerned with the relative performance of short constraint length convolutional codes vis-a-vis block codes when used in conjunction with either BPSK or DPSK modulation on the classical Rician fading channel. A variety of soft-decision decoding algorithms is considered for block codes while the Viterbi algorithm is used exclusively for decoding convolutional codes. Results indicate a substantial performance/complexity advantage in favor of short constraint length convolutional codes and Viterbi decoding which increases with fading severity. The work reported here extends the well-known performance advantage of convolutional codes on the AWGN channel to representative fading channels.
    Keywords: COMMUNICATIONS AND RADAR
    Type: In: NTC ''77; National Telecommunications Conference; Dec 05, 1977 - Dec 07, 1977; Los Angeles, CA
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 83
    facet.materialart.
    Unknown
    Measured results of polarization crosstalk cancellation using LMS control (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: This paper discusses the use of wideband decoupling networks for the cancellation of polarization crosstalk in dual-polarized communication links. Measured cancellation performance for an all-electronic IF network and an RF electro-mechanical waveguide network are presented. Each of these networks utilizes LMS-type adaptive control techniques to adjust the cancellation network.
    Keywords: COMMUNICATIONS AND RADAR
    Type: In: NTC ''77; National Telecommunications Conference; Dec 05, 1977 - Dec 07, 1977; Los Angeles, CA
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 84
    facet.materialart.
    Unknown
    Antenna bias rigging for performance objective (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: An optimum bias rigging for a paraboloidal antenna can be used to minimize the expected average mean-square half-pathlength surface deviations. Statistics of deep space planetary missions are employed to develop weighting factors for antenna elevation angles during these missions. A procedure is shown to compute the optimum rigging angle from these weights.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Mechanical Engineering in Radar Symposium; Nov 08, 1977 - Nov 10, 1977; Arlington, VA
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 85
    facet.materialart.
    Unknown
    Evaluating computed distortions of parabolic reflectors (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Distortion outputs from structural analysis of a 64-m paraboloidal reflector are analyzed by two computer programs for their radio-frequency performance characteristics. The computed and field measured values are compared.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Mechanical Engineering in Radar Symposium; Nov 08, 1977 - Nov 10, 1977; Arlington, VA
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 86
    facet.materialart.
    Unknown
    Analysis and design of a high tip speed, low noise aircraft fan incorporating swept leading edge rotor and stator blades (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-135092 , BBN-3332
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 87
    facet.materialart.
    Unknown
    Approximations to microwave attenuation in precipitation (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A three-term approximation and a discrete drop-size distribution have been used to obtain an analytical expression for the microwave attenuation coefficient for precipitation. Results compared to an exact calculation using the same drop size distribution showed a relative difference of 50% or less over a broad range of rainrates (5-150 mm/hr) and wavelengths (2-5 cm). Since the use of a discrete drop-size distribution is computationally complex, the exponential size distribution formulated by Marshall and Palmer (1948) was studied. This distribution resulted in an overprediction of the attenuation coefficient of as much as 100% at a 2 cm wavelength and a 150 mm/hr rainrate, although the prediction was much closer at lower rainrates and different wavelengths.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Conference on Radar Meteorology; Oct 26, 1976 - Oct 29, 1976; Seattle, WA
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 88
    facet.materialart.
    Unknown
    K-band attenuation by rain at constant reflectivity (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The paper considers a radar method of determining rain intensity which uses a dual wavelength system to measure both reflectivity Z and attenuation A and solving for the constants in an assumed exponential drop size distribution. Calculations are confined to the K-band, relations between A and the rain intensity R being determined for different values of Z for wavelengths of 0.86 and 1.24 cm. It is shown that measurements of reflectivity and attenuation by a dual wavelength radar can provide separate derivations of rain intensity. Available data on errors in an A-R relation indicate that the derivation from the attenuation measurement will be no better than from the Z-R relation.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Conference on Radar Meteorology; Oct 26, 1976 - Oct 29, 1976; Seattle, WA
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 89
    facet.materialart.
    Unknown
    Application of polynomial techniques to multivariable control of jet engines (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: This paper describes a complete case study of the application of the theory of minimal design to multivariable control of jet engines. The minimal-design problem is approached from the viewpoint of polynomial modules, and computational experience with PL/I and FORMAC-PL/I software is discussed. The complete minimal-design solution exhibits flexibilities not apparent in early industry studies, and a matrix approach to pole assignment can be used to advantage in this situation.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: International Symposium on Multivariable technological systems; Jul 04, 1977 - Jul 08, 1977; New Brunswick; Canada
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 90
    facet.materialart.
    Unknown
    Direct-connect test of a hydrogen-fueled three-strut injector for an integrated modular scramjet engine (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The study aims at illustrating the effects of strut and injector interactions and strut wakes not totally simulated in previous, less complex, direct-connect hardware. In addition, the influence of the relative location of the injectors on opposite sides of each strut and the effect of injector spacing are evaluated. It is shown that better mixing efficiency is attained by locating the fuel injectors on opposite sides of a strut so that the jets come together, rather than being staggered, in the strut wake. It is not possible to determine the combustion efficiency by means of a one-dimensional analysis of the wall pressure.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Combustion Meeting; Aug 15, 1977 - Aug 17, 1977; Colorado Springs, CO
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 91
    facet.materialart.
    Unknown
    A digitally implemented communications experiment utilizing the Hermes (CTS) satellite (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The Hermes (CTS) experiment program made possible a significant effort directed toward new developments which will reduce the costs associated with the distribution of satellite services. Advanced satellite transponder technology and small inexpensive earth terminals were demonstrated as part of the Hermes program. Another system element that holds promise for reduced transmission cost is associated with the communication link implementation. An experiment is described which uses CTS to demonstrate digital link implementation and its advantages over conventional analog systems. A Digitally Implemented Communications experiment which demonstrates the flexibility and efficiency of digital transmission of television video and audio, telephone voice and high-bit-rate data is also described. Presentation of the experiment concept which concentrates on the evaluation of full-duplex digital television in the teleconferencing environment is followed by a description of unique equipment that was developed.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA-TM-73827 , Symp. on Hermes (Comm. Technol. Satellite) its Performance and Appl.; Nov 29, 1977 - Dec 01, 1977; Ottawa, Ontario; Canada
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 92
    facet.materialart.
    Unknown
    An empirical model for inverted-velocity-profile jet noise prediction (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: An empirical model for predicting the noise from inverted-velocity-profile coaxial or coannular jets is presented and compared with small-scale static and simulated flight data. The model considered the combined contributions of as many as four uncorrelated constituent sources: the premerged-jet/ambient mixing region, the merged-jet/ambient mixing region, outer-stream shock/turbulence interaction, and inner-stream shock/turbulence interaction. The noise from the merged region occurs at relatively low frequency and is modeled as the contribution of a circular jet at merged conditions and total exhaust area, with the high frequencies attenuated. The noise from the premerged region occurs at high frequency and is modeled as the contribution of an equivalent plug nozzle at outer stream conditions, with the low frequencies attenuated.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-73838 , E-9425 , Meeting of the Acoustical Soc. of Am.; Dec 13, 1977 - Dec 16, 1977; Miami, FL; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 93
    facet.materialart.
    Unknown
    The promise of eutectics for aircraft turbines (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The current status of the first generation eutectics, gamma/gamma transition - delta and NiTaC-13, is described in detail. Several second generation systems, such as gamma/gamma transition - alpha and NiTaC 3-116A, gamma - beta, and COTAC 74 are also reviewed with particular emphasis on their critical physical and mechanical properties, future research directions, and potential applications. Results of recent cost-benefit analyses of eutectic turbine blades are discussed.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-73714 , E-9258 , Mater. Show and Conf.; Oct 25, 1977 - Oct 27, 1977; Chicago
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 94
    facet.materialart.
    Unknown
    New lidar concept for measuring the slant range transmission in aircraft landing approaches (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The single-scatter, single-wavelength, scalar-backscatter lidar equation is investigated to determine the transmission along a line from a point on the ground to what is known as the decision point on the 3 degree aircraft glide slope. It may be applied in aircraft landing approaches for measuring the slant range transmission.
    Keywords: COMMUNICATIONS AND RADAR
    Type: International Laser Radar Conference on Laser Atmospheric Studies; Jun 06, 1977 - Jun 09, 1977; Philadelphia, PA; US
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 95
    facet.materialart.
    Unknown
    Direct-connect tests of hydrogen-fueled supersonic combustors (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Direct-connect tests of hydrogen-fueled supersonic combustors were performed using arc-heated air at combustor inlet Mach numbers of 2.9 to 3.2. Various axisymmetric combustor geometries of 5.89 and 6.96 cm (inner diameter) inlet were investigated; the fuel was injected from the wall either from a ring of equally spaced holes normal to the air stream, or from a circumferential slot oriented 45 deg downstream. The hole-type injectors consistently gave better results. The effects of various parameters are examined, and the performance comparison procedure is described. A theoretical model of the supersonic combustion process which includes a precombustion shock-compression is used to explain the character of the observed pressure distributions and to assess the effects of the measured heat transfer rates, deduced wall shear, and combustor geometry on performance.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: International Symposium on Combustion; Aug 15, 1976 - Aug 20, 1976; Cambridge, MA
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 96
    facet.materialart.
    Unknown
    Composite hubs for low cost turbine engines (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A detailed stress analysis is performed using NASTRAN to demonstrate theoretically the adequacy of composite hubs for low cost turbine engine applications. The results show that composite hubs are adequate for this application from the steady state stress viewpoint.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Annual Conference on Discover reinforced plastics; Feb 08, 1977 - Feb 11, 1977; Washington, DC
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 97
    facet.materialart.
    Unknown
    Static performance of vectoring/reversing non-axisymmetric nozzles (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: An experimental program sponsored by the Air Force Flight Dynamics Laboratory is currently in progress to determine the internal and installed performance characteristics of five different thrust vectoring/reversing non-axisymmetric nozzle concepts for tactical fighter aircraft applications. Internal performance characteristics for the five non-axisymmetric nozzles and an advanced technology axisymmetric baseline nozzle were determined in static tests conducted in January 1977 at the NASA-Langley Research Center. The non-axisymmetric nozzle models were tested at thrust deflection angles of up to 30 degrees from horizontal at throat areas associated with both dry and afterburning power. In addition, dry power reverse thrust geometries were tested for three of the concepts. The best designs demonstrated internal performance levels essentially equivalent to the baseline axisymmetric nozzle at unvectored conditions. The best designs also gave minimum performance losses due to vectoring, and reverse thrust levels up to 50% of maximum dry power forward thrust. The installed performance characteristics will be established based on wind tunnel testing to be conducted at Arnold Engineering Development Center in the fall of 1977.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 77-840 , Propulsion Conference; Jul 11, 1977 - Jul 13, 1977; Orlando, FL; US
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 98
    facet.materialart.
    Unknown
    Measured effects of coolant injection on the performance of a film cooled turbine (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Tests have been conducted on a 20-inch diameter single-stage air-cooled turbine designed to evaluate the effects of film cooling air on turbine aerodynamic performance. The present paper reports the results of five test configurations, including two different cooling designs and three combinations of cooled and solid airfoils. A comparison is made of the experimental results with a previously published analytical method of evaluating coolant injection effects on turbine performance.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 77-946 , Propulsion Conference; Jul 11, 1977 - Jul 13, 1977; Orlando, FL; US
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 99
    facet.materialart.
    Unknown
    Aero-acoustic performance comparison of core engine noise suppressors on NASA quiet engine 'C' (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The purpose of the experimental program reported herein was to evaluate and compare the relative aero-acoustic effectiveness of two core engine suppressors, a contractor-designed suppressor delivered with the Quiet Engine, and a NASA-designed suppressor, designed and built subsequently. The NASA suppressor was tested with and without a splitter making a total of three configurations being reported in addition to the baseline hardwall case. The aerodynamic results are presented in terms of tailpipe pressure loss, corrected net thrust, and corrected specific fuel consumption as functions of engine power setting. The acoustic results are divided into duct and far-field acoustic data. The NASA-designed core suppressor did the better job of suppressing aft end noise, but the splitter associated with it caused a significant engine performance penalty. The NASA core suppressor without the splitter suppressed most of the core noise without any engine performance penalty.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 77-922 , Propulsion Conference; Jul 11, 1977 - Jul 13, 1977; Orlando, FL; US
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 100
    facet.materialart.
    Unknown
    Atmospheric effects on inlets for supersonic cruise aircraft (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Time response effects of atmospheric-type disturbances on inlets and some implications regarding inlet controls are considered. A study involving the simulation of a mixed-compression inlet is described. The study employs a linear dynamic analysis, modified for a significant nonlinearity. Transient disturbances in ambient temperature and pressure and wind gusts are considered independently at the inlet cruise Mach number of 2.5. The presented results show the maximum amplitude of a triangular-wave disturbance, that does not cause inlet unstart, as a function of disturbance pulse width.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 77-874 , Propulsion Conference; Jul 11, 1977 - Jul 13, 1977; Orlando, FL; US
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...