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Ona, A. L.↗
SEARCH · Engineering Papers
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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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Electrical Characterization of the RCA CPD1822SD Random Access Memory, Volume 2,
Raw data obtained from functional tests, data retention tests, and AC and DC parametric tests are presented along with schmoo plots. Rise/fall time screening results are included.
Klute, A.↗
An improved analysis/synthesis capability based on dual methods - ACCESS 3
Approximation concepts and dual method algorithms are combined to create a new method for minimum weight design of structural systems. Approximation concepts convert the basic mathematical programming statement of the structural synthesis problem into a sequence of explicit primal problems of separable form. These problems are solved by constructing explicit dual functions, which are maximized subject to nonnegativity constraints. The dual method is successfully extended to deal with pure discrete and mixed continuous-discrete design variable problems. The power of the method presented is illustrated with numerical results for example problems, including a thin delta wing with fiber composite skins.
Schmit, L. A.↗
A summary of Apollo lunar accessibility
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Cappellari, J. O., Jr.↗
Improved Parallel-Access Alinement Network
Network channels elements of data array from memory ports to processor ports using a hardware-generated binary control work. Depending on control work selected, data may be shifted in increments or transposed in each of three levels to reach appropriate processing ports. A similar arrangement with reversed wiring is used to return data from processing ports to respective memory modules. Selection gate used in network incorporates two AND gates feeding an OR gate. In some logic families the OR gate may be fabricated as a "wired OR".
Barnes, G. H.↗
A multiple access communication network based on adaptive arrays
A single frequency communication system is considered consisting of K possibly moving users distributed in space simultaneously communicating with a central station equipped with a computationally adapted array of n = or K antennas. Such a configuration could result if K spacecraft were to be simultaneously tracked by a single DSN complex consisting of an n antennas array. The array employs K sets of n weights to segregate the signals received from the K users. The weights are determined by direct computation based on known position information of the K users. Currently known techniques require (for n = K) about (4/3)K to the 4th power computer operations (multiply and add) to perform such computations. A technique that accomplishes this same goal in 8 K to the 3rd power operations, yielding a reduction by a factor K/6, was developed.
Zohar, S.↗
A comparison of multiple access protocols for packet switching in satellite-switched multi-beam systems
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Gadre, J.↗
Man-made space debris - Does it restrict free access to space
Consideration is given to the hazards posed by existing and future man-made space debris to spacecraft operations. The components of the hazard are identified as those fragments resulting from spacecraft explosions and spent stages which can be tracked, those fragments which are too small to be tracked at their present distances, and future debris, which, if present trends in spacecraft design and operation continue, may lead to an unacceptably high probability of collision with operational spacecraft within a decade. It is argued that a coordinated effort must be undertaken by all space users to evaluate means of space debris control in order to allow for the future unrestricted use of near-earth space. A plan for immediate action to forestall the space debris problem by activities in the areas of education, debris monitoring and collection technology, space vehicle design, space operational procedures and practices and space policies and treaties is proposed.
Wolfe, M.↗
Deep-Access Valve Wrench
Bent rod on modified basin wrench holds wrench jaw against valve stem. Rod swivels to accomodate 180 degrees rotation of wrench jaw. Valves 5 feet (1.5 meters) underground can be operated with tool.
Fleck, H. E.↗
Next generation communications satellites: multiple access and network studies
Efficient resource allocation and network design for satellite systems serving heterogeneous user populations with large numbers of small direct-to-user Earth stations are discussed. Focus is on TDMA systems involving a high degree of frequency reuse by means of satellite-switched multiple beams (SSMB) with varying degrees of onboard processing. Algorithms for the efficient utilization of the satellite resources were developed. The effect of skewed traffic, overlapping beams and batched arrivals in packet-switched SSMB systems, integration of stream and bursty traffic, and optimal circuit scheduling in SSMB systems: performance bounds and computational complexity are discussed.
Meadows, H. E.↗
Nimbus 6 Random Access Measurement System applications experiments
The advantages of a technique in which data collection platforms randomly transmit signal to a polar orbiting satellite, thus eliminating satellite interrogation are demonstrated in investigations of the atmosphere; oceanographic parameters; Arctic regions and ice conditions; navigation and position location; and data buoy development.
Cote, C. E.↗
Transferability and data access issues
The evolution and current operational mode of the domestic information display system (DIDS) now known as the decision information display system are described. This minicomputer based system, developed from a NASA-generated image processing system, was designed to display federal statistical data for a variety of geographic areas in the form of choropleth maps. The application of DIDS in South Carolina is discussed as well as the progress made and issues that emerged in using the data base on a state and county level. The hardware base for the system, how this user friendly system works, and the possibility of transferring data to remote systems are examined.
Ferreros, A. V.↗
Mathematical models for cochannel interference in FH/MFSK multiple-access systems
FH/MFSK has been proposed for a multiuser spread spectrum digital communication system to combat both self-jamming and intentional jamming. An independence assumption at the energy detector outputs is used to evaluate such a system for a digitized voice mobile radio system (Yue, 1981). This paper presents a correlated model and compares its performance to an independence model under the symbol error probability criterion. A Gaussian process model is also developed for comparison. It is found that the conventional Gaussian approximation is inadequate in predicting the number of users that can be accommodated by an FH/MFSK system using the conventional receiver. Furthermore, for the cases evaluated, the independence model provides an excellent approximation to the correlated model. Additionally, a conditional Chernoff bound is presented for the more general case of frequency-hopping systems with multiple hops per symbol.
Yan, T.-Y.↗
Multi-access fiber optic data bus using FDM/FSK
The major thrust was to develop a T coupler with very low (0.1 0.2dB) in-line loss. This is essential to any multiaccess bus structure where the word multi implies fifteen or more nodes on the bus, and it is tacitly assumed to be a passive bus. (Reliability considerations tend to exclude the use of active nodes - repeater nodes.)
Zanger, H.↗
Grooming the Shuttle for cost-effective access to space
An assessment is made of the performance of the Space Shuttle-based Space Transportation System (STS) from the initial flights in 1981 to the present, which has involved the launching of 12 satellites and the retrieval of two. It is expected that the STS will soon be able to schedule 24 routine missions/year, upon the achievement of full operational status for the full fleet of four Space Shuttles and the completion of support facilities at both the Kennedy Space Center and Vandenberg Air Force Base. The prospects for space industrialization efforts based on STS are noted.
Moore, J. W.↗
Restricted access processor - An application of computer security technology
This paper describes a security guard device that is currently being developed by Computer Sciences Corporation (CSC). The methods used to provide assurance that the system meets its security requirements include the system architecture, a system security evaluation, and the application of formal and informal verification techniques. The combination of state-of-the-art technology and the incorporation of new verification procedures results in a demonstration of the feasibility of computer security technology for operational applications.
Mcmahon, E. M.↗
Easily Accessible Camera Mount
Modified mount enables fast alinement of movie cameras in explosionproof housings. Screw on side and readily reached through side door of housing. Mount includes right-angle drive mechanism containing two miter gears that turn threaded shaft. Shaft drives movable dovetail clamping jaw that engages fixed dovetail plate on camera. Mechanism alines camera in housing and secures it. Reduces installation time by 80 percent.
Chalson, H. E.↗
Four spot laser anemometer and optical access techniques for turbine applications
A time-of-flight anemometer (TOFA) system, utilizing a spatial lead-lag filter for bipolar pulse generation was constructed and tested. This system, called a Four Spot Laser Anemometer, was specifically designed for use in high speed, turbulent flows in the presence of walls or surfaces. The TOFA system uses elliptical spots to increase the flow acceptance angle to be comparable with that of a fringe type anemometer. The tightly focused spots used in the Four Spot yield excellent flare light rejection capabilities. Good results were obtained to 75 microns normal to a surface, with a f/2.5 collecting lens. This system is being evaluated for use in a warm turbine facility. Results from both a particle lag velocity experiment and boundary layer profiles will be discussed. In addition, an analysis of the use of curved windows in a turbine casing will be presented. Curved windows, matching the inner radius of the turbine casing, preserve the flow conditions, but introduce astigmatic aberrations. A correction optic was designed that virtually eliminates these astigmatic aberrations throughout the intrablade survey region for normal incidence.
Wernet, Mark P.↗