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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

A system for analysis and classification of voice communications

A method for analysis and classification of verbal communications typically associated with manned space missions or simulations was developed. The study was carried out in two phases. Phase 1 was devoted to identification of crew tasks and activities which require voice communication for accomplishment or reporting. Phase 2 entailed development of a message classification system and a preliminary test of its feasibility. The classification system permits voice communications to be analyzed to three progressively more specific levels of detail and to be described in terms of message content, purpose, and the participants in the information exchange. A coding technique was devised to allow messages to be recorded by an eight-digit number.

Older, H. J.↗
NASA NTRS1996

VLSI Neural Networks Help To Compress Video Signals

Advanced analog/digital electronic system for compression of video signals incorporates artificial neural networks. Performs motion-estimation and image-data-compression processing. Effectively eliminates temporal and spatial redundancies of sequences of video images; processes video image data, retaining only nonredundant parts to be transmitted, then transmits resulting data stream in form of efficient code. Reduces bandwidth and storage requirements for transmission and recording of video signal.

Fang, Wai-Chi↗
NASA NTRS1993

Magellan Recorder Data Recovery Algorithms

This paper describes algorithms implemented by the Magellan High Rate Processor to recover radar data corrupted by the failure of an onboard tape recorder that dropped bits. For data with error correction coding, an algorithm was developed that decodes data in the presence of bit errors and missing bits.

Error↗
NASA NTRS2018

Cardiovascular Disease Outcomes Among the NASA Astronaut Corps

BACKGROUND: Acute effects of spaceflight on the cardiovascular system have been studied extensively, but the combined chronic effects of spaceflight and aging are not well understood. Preparation for and participation in spaceflight activities are associated with changes in the cardiovascular system such as decreased carotid artery distensibility and decreased ventricular mass which may lead to an increased risk of cardiovascular disease. Additionally, astronauts who travel into space multiple times or for longer durations may be at an increased risk across their lifespan. To that end, the purpose of this study was to determine the incidence of common cardiovascular disease (CVD) outcomes among the NASA astronaut corps during their active career and through retirement. METHODS: Cardiovascular disease outcomes were defined as reports of any of the following: myocardial infarction (MI), revascularization procedures (coronary artery bypass graft surgery [CABG] or percutaneous coronary intervention [PCI]), hypertension, stroke or transient ischemic attack [TIA], heart failure, or total CVD (as defined by the AHA - combined outcome of MI, Angina Pectoris, heart failure, stroke, and hypertension). Each outcome was identified individually from review of NASA's Electronic Medical Record (EMR), EKG reports, and death certificates using ICD-9 codes as well as string searches of physician notes of astronaut exams that occurred between 1959 and 2016. RESULTS: Of 338 NASA astronauts selected as of 2016, 9 reported an MI, 12 reported a revascularization procedure, (7 PCI and 5 CABG), 4 reported Angina (without MI), 5 reported heart failure, 9 reported stroke/TIA, and 96 reported hypertension. Total CVD was reported in 105 astronauts. No astronaut who had an MI or revascularization procedure flew a spaceflight mission following the event. All MI, revascularization, and stroke events occurred in male astronauts. When reviewing astronaut ECG reports, abnormal ECG reports were found in only 8% of records (n=430) and mainly among retired astronauts (82%), with marked sinus bradycardia being the reason for the abnormal classification.

Charvat, Jacqueline M.↗
NASA NTRS1994

Mapping Between Distinct Reed-Solomon Codes

One-to-one mapping between two Reed-Solomon (RS) codes devised to enable decoder designed for one of codes to operate on other one also. Codes in question must have same N and K parameters (defined below) but otherwise be two distinct RS codes. Mapping intended to enable same ground-based decoder to decode telemetry signals from two spacecraft in two different RS codes of (N,K) = (255,223). Also useful in purely terrestrial data communications and in optical and magnetic recording and playback of digitized audio and video signals. Implemented in interface circuitry and/or software to enable communication between coding systems of different manufacturers using different RS codes within same (N,K) family.

Perlman, Marvin↗
NASA NTRS1989

More On The Decoder-Error Probability Of Reed-Solomon Codes

Paper extends theory of decoder-error probability for linear maximum-distance separable (MDS) codes. General class of error-correcting codes includes Reed-Solomon codes, important in communications with distant spacecraft, military communications, and compact-disk recording industry. Advancing beyond previous theoretical developments that placed upper bounds on decoder-error probabilities, author derives an exact formula for probability PE(u) that decoder will make error when u code symbols in error.

Cheung, Kar-Ming↗
NASA NTRS1992

Analysis of DGPS/INS and MLS/INS final approach navigation errors and control performance data

Flight tests were conducted jointly by NASA Langley Research Center and Honeywell, Inc., on a B-737 research aircraft to record a data base for evaluating the performance of a differential DGPS/inertial navigation system (INS) which used GPS Course/Acquisition code receivers. Estimates from the DGPS/INS and a Microwave Landing System (MLS)/INS, and various aircraft parameter data were recorded in real time aboard the aircraft while flying along the final approach path to landing. This paper presents the mean and standard deviation of the DGPS/INS and MLS/INS navigation position errors computed relative to the laser tracker system and of the difference between the DGPS/INS and MLS/INS velocity estimates. RMS errors are presented for DGPS/INS and MLS/INS guidance errors (localizer and glideslope). The mean navigation position errors and standard deviation of the x position coordinate of the DGPS/INS and MLS/INS systems were found to be of similar magnitude while the standard deviation of the y and z position coordinate errors were significantly larger for DGPS/INS compared to MLS/INS.

Hueschen, Richard M.↗
NASA NTRS1973

Television multiplexing system

A television multiplexing system which includes a circuit that inserts a digital codes sync signal and a digital code into a video signal for identifying the channel is described. The digital sync signal and the digital coded signals are generated by a single crystal controlled clock so that they are always in synchronism with each other. In demultiplexing the signals are utilized for shifting the digital coded signals into a shift register. The shift register, in turn, activates a decoder according to the code stored in the shift register for selecting the proper recording disk or receiver for storing the video signal.

Simpkins, L. G.↗
NASA NTRS1972

The Mariner Venus Mercury flight data subsystem.

The flight data subsystem (FDS) discussed handles both the engineering and scientific measurements performed on the MVM'73. It formats the data into serial data streams, and sends it to the modulation/demodulation subsystem for transmission to earth or to the data storage subsystem for storage on a digital tape recorder. The FDS is controlled by serial digital words, called coded commands, received from the central computer sequencer of from the ground via the modulation/demodulation subsystem. The eight major blocks of the FDS are: power converter, timing and control, engineering data, memory, memory input/output and control, nonimaging data, imaging data, and data output. The FDS incorporates some 4000 components, weighs 17 kg, and uses 35 W of power. General data on the mission and spacecraft are given.

Whitehead, P. B.↗
NASA NTRS1994

Making Diamondlike Films More Transparent

Diamondlike carbon films highly transparent to visible light made by dual-ion-beam deposition process. Hard, resistant to scratching, and hermetic. Used as protective coatings on eyeglasses, magnetic recording heads, computer hard disks, and windows in bar-code scanners. Amorphous diamondlike carbon films preferable to polycrystalline diamond films in these and other applications. Smooth and adherent and deposited at room temperature.

Mirtich, Michael J.↗
NASA NTRS2013

A Post-Processing Receiver for the Lunar Laser Communications Demonstration Project

The Lunar Laser Communications Demonstration Project undertaken by MIT Lincoln Laboratory and NASA's Goddard Space Flight Center will demonstrate high-rate laser communications from lunar orbit to the Earth. NASA's Jet Propulsion Laboratory is developing a backup ground station supporting a data rate of 39 Mbps that is based on a non-real-time software post-processing receiver architecture. This approach entails processing sample-rate-limited data without feedback in the presence high uncertainty in downlink clock characteristics under low signal flux conditions. In this paper we present a receiver concept that addresses these challenges with descriptions of the photodetector assembly, sample acquisition and recording platform, and signal processing approach. End-to-end coded simulation and laboratory data analysis results are presented that validate the receiver conceptual design.

optical communications↗
NASA NTRS2016

Ice Accretions and Full-Scale Iced Aerodynamic Performance Data for a Two-Dimensional NACA 23012 Airfoil

This report documents the data collected during the large wind tunnel campaigns conducted as part of the SUNSET project (StUdies oN Scaling EffecTs due to ice) also known as the Ice-Accretion Aerodynamics Simulation study: a joint effort by NASA, the Office National d'Etudes et Recherches Aérospatiales (ONERA), and the University of Illinois. These data form a benchmark database of full-scale ice accretions and corresponding ice-contaminated aerodynamic performance data for a two-dimensional (2D) NACA 23012 airfoil. The wider research effort also included an analysis of ice-contaminated aerodynamics that categorized ice accretions by aerodynamic effects and an investigation of subscale, low- Reynolds-number ice-contaminated aerodynamics for the NACA 23012 airfoil. The low-Reynolds-number investigation included an analysis of the geometric fidelity needed to reliably assess aerodynamic effects of airfoil icing using artificial ice shapes. Included herein are records of the ice accreted during campaigns in NASA Glenn Research Center's Icing Research Tunnel (IRT). Two different 2D NACA 23012 airfoil models were used during these campaigns; an 18-in. (45.7-cm) chord (subscale) model and a 72-in. (182.9-cm) chord (full-scale) model. The aircraft icing conditions used during these campaigns were selected from the Federal Aviation Administration's (FAA's) Code of Federal Regulations (CFR) Part 25 Appendix C icing envelopes. The records include the test conditions, photographs of the ice accreted, tracings of the ice, and ice depth measurements. Model coordinates and pressure tap locations are also presented. Also included herein are the data recorded during a wind tunnel campaign conducted in the F1 Subsonic Pressurized Wind Tunnel of ONERA. The F1 tunnel is a pressured, high- Reynolds-number facility that could accommodate the full-scale (72-in. (182.9-cm) chord) 2D NACA 23012 model. Molds were made of the ice accreted during selected test runs of the full-scale model in the IRT. From these molds, castings were made that closely replicated the features of the accreted ice. The castings were then mounted on the full-scale model in the F1 tunnel, and aerodynamic performance measurements were made using model surface pressure taps, the facility force balance system, and a large wake rake designed specifically for these tests. Tests were run over a range of Reynolds and Mach numbers. For each run, the model was rotated over a range of angles-of-attack that included airfoil stall. The benchmark data collected during these campaigns were, and continue to be, used for various purposes. The full-scale data form a unique, ice-accretion and associated aerodynamic performance dataset that can be used as a reference when addressing concerns regarding the use of subscale ice-accretion data to assess full-scale icing effects. Further, the data may be used in the development or enhancement of both ice-accretion prediction codes and computational fluid dynamic codes when applied to study the effects of icing. Finally, as was done in the wider study, the data may be used to help determine the level of geometric fidelity needed for artificial ice used to assess aerodynamic degradation due to aircraft icing. The structured, multifaceted approach used in this research effort provides a unique perspective on the aerodynamic effects of aircraft icing. The data presented in this report are available in electronic form upon formal approval by proper NASA and ONERA authorities.

Addy, Harold E., Jr.↗
NASA NTRS1985

High-density digital recording

The problems associated with high-density digital recording (HDDR) are discussed. Five independent users of HDDR systems and their problems, solutions, and insights are provided as guidance for other users of HDDR systems. Various pulse code modulation coding techniques are reviewed. An introduction to error detection and correction head optimization theory and perpendicular recording are provided. Competitive tape recorder manufacturers apply all of the above theories and techniques and present their offerings. The methodology used by the HDDR Users Subcommittee of THIC to evaluate parallel HDDR systems is presented.

Kalil, F.↗
NASA NTRS2009

System Synchronizes Recordings from Separated Video Cameras

A system of electronic hardware and software for synchronizing recordings from multiple, physically separated video cameras is being developed, primarily for use in multiple-look-angle video production. The system, the time code used in the system, and the underlying method of synchronization upon which the design of the system is based are denoted generally by the term "Geo-TimeCode(TradeMark)." The system is embodied mostly in compact, lightweight, portable units (see figure) denoted video time-code units (VTUs) - one VTU for each video camera. The system is scalable in that any number of camera recordings can be synchronized. The estimated retail price per unit would be about $350 (in 2006 dollars). The need for this or another synchronization system external to video cameras arises because most video cameras do not include internal means for maintaining synchronization with other video cameras. Unlike prior video-camera-synchronization systems, this system does not depend on continuous cable or radio links between cameras (however, it does depend on occasional cable links lasting a few seconds). Also, whereas the time codes used in prior video-camera-synchronization systems typically repeat after 24 hours, the time code used in this system does not repeat for slightly more than 136 years; hence, this system is much better suited for long-term deployment of multiple cameras.

Nail, William↗
NASA NTRS1982

LARSPEC spectroradiometer-multiband radiometer data formats

The data base software system, LARSPEC, is discussed and the data base format for agronomic, meteorological, spectroradiometer, and multiband radiometer data is described. In addition, the contents and formats of each record of data and the wavelength tables are listed and the codes used for some of the parameters are described.

Biehl, L. L.↗
NASA NTRS1990

Simplified Correction Of Errors In Reed-Solomon Codes

New decoder realized by simplified pipeline architecture. Simplified procedure for correction of errors and erasures in Reed-Solomon codes expected to result in simpler decoding equipment. Development widens commercial applicability of Reed-Solomon codes, used to correct bursts of errors in digital communication and recording systems. Improved decoder less complex. Made more regular, simple, and suitable for implementation in both VLSI and software.

Truong, T. K.↗
NASA NTRS1997

Development of an Automated Reader for Analysis and Storage of Personnel Dosimeter Badge Data

The collection and archiving of data from personnel dosimeters has become increasingly important in light of the lowered Threshold Limit Values (TLV) for HydraZine (HZ), MonoMethylHydrazine (MMH), and Unsymmetrical DiMethylHydrazine (UDMH). The American Conference of Government Industrial Hygienists (ACGIH) lowered the TLV from 100 parts per billion (ppb) to IO ppb and has caused increased concern over long term exposures of personnel to trace levels of these hypergols and other potentially harmful chemicals. An automated system of reading the exposure levels of personnel dosimeters and storing exposure data for subsequent evaluation has been developed. The reading of personnel dosimeter badges for exposure to potentially harmful vapor concentrations of hydrazines or other chemicals is performed visually by comparing the color developed by the badge with a calibrated color comparator. The result obtained using visual comparisons of the developed badge color with the comparator may vary widely from user to user. The automated badge reader takes the variability out of the dosimeter reading by accurately comparing the reflectance obtained from a colored spot on the badge with a reading on the same spot prior to any exposure to chemical vapors. The observed difference between the reflectance values is used as part of a calculation of the dose value for the badge based on a stored calibration curve. The badge reader also stores bar-code data unique to each badge, as well as bar-code information on the user, as part of the permanent badge record. The start and stop exposure times for each badge are recorded and can be used as part of the calculated concentration, in ppm, for each badge logged during a recording period. The badge reader is equipped with a number of badge holders, each of which is unique to a specific type of personnel dosimeter badge. This gives the reader maximum flexibility to allow for the reading of several different types of badges. Test results of the badge reader for several different types of personnel dosimeter badges are presented within the body of this paper.

Meneghelli, B. J.↗