Control of large space antennas: Wrap-rib-hoop/column
Control work for large space antenna systems is discussed. Included are the wrap-rib and hoop/column antenna concepts for communications and radiometry.
Lin, Y. H.↗
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Wrap-rib antenna concept development overview
The wrap rib antenna design of a parabolic reflector large space antenna is discussed. Cost estimates, design/mission compatibility, deployment sequence, ground based tests, and fabrication are discussed.
Woods, A. A., Jr.↗
Wrapped Wire Detects Rupture Of Pressure Vessel
Simple, inexpensive technique helps protect against damage caused by continuing operation of equipment after rupture or burnout of pressure vessel. Wire wrapped over area on outside of vessel where breakthrough most likely. If wall breaks or burns, so does wire. Current passing through wire ceases, triggering cutoff mechanism stopping flow in vessel to prevent further damage. Applied in other situations in which pipes or vessels fail due to overpressure, overheating, or corrosion.
Hunt, James B.↗
Strength, Fatigue, and Fracture Toughness of Ti-6Al-4V Liner from a Composite Over-Wrapped Pressure Vessel
It was demonstrated by way of experiment that Composite Over-wrapped Pressure Vessel (COPV) Ti-6Al-4V liner material can sustain the expected service loads and cycles. The experiments were performed as part of investigations on the residual life of COPV tanks being used in Space Shuttle Orbiters. Measured properties included tensile strength, compressive strength, reversed loading cycles to simulate liner proof strains, and cyclic fatigue loading to demonstrate the ability to sustain 1000 cycles after liner buckling. The liner material came from a salvaged 40 in. Columbia (orbiter 102) tank (SN029), and tensile strength measurements were made on both boss-transition (thick) and membrane regions (thin). The average measured yield strength was 131 ksi in the boss-transition and membrane regions, in good agreement with measurements made on 1970 s vintage forged plate stock. However, Young s modulus was 17.4+/-0.3 Msi, somewhat higher than typical handbook values (approx.16 Msi). The fracture toughness, as estimated from a failed fatigue specimen, was 74 ksi/sq in, in reasonable agreement with standardized measurements made on 1970 s vintage forged plate stock. Low cycle fatigue of a buckled test specimen implied that as-imprinted liners can sustain over 4000 load cycles.
Salem, Jonathan A.↗
Printed Circuit Board Quality: Copper Wrap
Outline: Motivation and introduction, requirements in standards and issues, experimental verification, simulation assisted evaluation, lessons learned.
PLATING↗
Development of techniques and hardware for insulation wrappings of cryogenic containers Eighth quarterly progress report, Aug. - Oct. 1965
Helium purged superinsulation system for cryogenic storage
CRYOGENIC STORAGE↗
LM landing radar: General procedure for solderless wire wrap connections
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Source record↗
Study of wrap-rib antenna design
The results of a parametric design study conducted to develop the significant characteristics and technology limitations of space deployable antenna systems with aperture sizes ranging from 50 up to 300 m and F/D ratios between 0.5 and 3.0 are presented. Wrap/rib type reflectors of both the prime and offset fed geometry and associated feed support structures were considered. The significant constraints investigated as limitations on achievable aperture were inherent manufacturability, orbit dynamic and thermal stability, antenna weight, and antenna stowed volume. A data base, resulting in the defined maximum achievable aperture size as a function of diameter, frequency and estimated cost, was formed.
Wade, W. D.↗
Offset wrap rib antenna concept development
The demonstration of 50 to 150 m, STS compatible, offset antenna technology readiness is reported. Fabrication of a ground and flight testable partial 55 m reflector section and feed support structure is discussed. Reduction to practice through ground test verification is presently contained in the program. Key objectives for the program include the design of a compatible feed support structure and the fabrication and testing of critical components.
Woods, A. A., Jr.↗
Overview: Western Regional applications Program (WRAP) status
Interactions with all 14 of the states in the Western Region over the past three years are reviewed from NASA's perspective. Outreach and training programs using the M mobile analysis and training extension van, the University Program, classes at the Ames Center, demonstration tests with state agencies, and surveying the needs of local governments are highlighted. Planned activities, the continuance of ASVT's, and the impact of the budget cuts on NASA'S technology program are also considered.
Norman, S. M.↗
Wrap-up session
Listening to the case studies that were presented it became quite evident that the best data management systems were the ones where data managers and research scientists worked as a team developed in the early stages of project planning. Examples that were given included WOCE Data Assembly Centres e.g., Drifters, the Global Temperature Salinity Pilot Project (GTSPP) collaboration with Joint Analyses Centres in the U.S. and Australia, and JGOFS/BOFS development of Topical Centres. While each of these has some elements unique to the project, each had brought together 'teams' of Principal Investigators (PI's) and data management experts at an early stage of project development. Conversely, projects which had considered data management as a totally separate activity with lower priority often failed to provide the service required to meet scientific objectives. Therefore, the following actions should be brought to the attention of relevant groups within the IOC and other international organizations: (1) Publicize, at the national and international level, underway data/scientist collaborations that may be used as models in planning for the future. (2) Reduce adversarial situations where data managers and scientists appear to be in competition. (3) Colocation and other forms of collaboration often results in very high quality data sets and more timely data submission. Improved timeliness of data submissions was a common theme throughout the workshop and must be considered an important element in all future plans. Improvements in timely submission of data were noted. In order to continue this trend the advantages of timely submission of data must be stressed to those planning new ocean science projects.
Holland, Geoffrey↗
Analysis of cylindrical wrap-around and doubly conformal patch antennas by way of the finite element-artificial absorber method
The goal of this project was to develop analysis codes for computing the scattering and radiation of antennas on cylindrically and doubly conformal platforms. The finite element-boundary integral (FE-BI) method has been shown to accurately model the scattering and radiation of cavity-backed patch antennas. Unfortunately extension of this rigorous technique to coated or doubly curved platforms is cumbersome and inefficient. An alternative approximate approach is to employ an absorbing boundary condition (ABC) for terminating the finite element mesh thus avoiding use of a Green's function. A FE-ABC method is used to calculate the radar cross section (RCS) and radiation pattern of a cavity-backed patch antenna which is recessed within a metallic surface. It is shown that this approach is accurate for RCS and antenna pattern calculations with an ABC surface displaced as little as 0.3 lambda from the cavity aperture. These patch antennas may have a dielectric overlay which may also be modeled with this technique.
Volakis, J. L.↗
Dirbe evidence for a wrap in the interstellar dust layer and stellar disk of the galaxy
The Diffuse Infrared Background Experiment (DIRBE) of the Cosmic Background Explorer (COBE) has mapped the surface brightness distributions of the Galactic plane at wavelengths from 1.25 to 240 micrometers. In these maps the latitude of peak brightness, as a function of longitude, traces a roughly sinusoidal curve of period approximately 360 deg. In the far-infrared, where emission by interstellar dust dominates the surface brightness, this curve agrees well with that derived from maps of the velocity-integrated H 1, suggesting that the layers of dust and neutral atomic hydrogen are similarly displaced from the Galactic plane. In the near-infrared (lambda less than 5 micrometers), where old disk stars dominate the emission, the brightness crest exhibits the same phase but roughly half the amplitude. The reduced amplitude of the warp in stellar light could result from a lesser warping of the stellar disk, or from a more rapid falloff of the density of stars relative to the density of gas, possibly due to a radial truncation of the disk.
Freudenreich, H. T.↗
Braiding And Wrapping Tape To Make A Composite Vessel
Braiding and forming combined in one-step process. In process, continuous plus or minus 45 degrees bias braided tape fabricated. Braiding done on site, and braided tape immediately wound on male mandrel in shinglelike configuration to make fabric preform. Subsequently, preform impregnated with matrix resin. Improved process does not produce stitches. Expected to yield consistent quality, to involve less handling of fabric, to produce less scrap, and thus to cost less.
Freitas, Glenn↗
Scalable Wrap-Around Shuffle Exchange Network with Deflection Routing
The invention in one embodiment is a communication network including plural non-blocking crossbar nodes, first apparatus for connecting the nodes in a first layer of connecting links, and second apparatus for connecting links independent of the first layer, whereby each layer is connected to the other layer at each point of the nodes. Preferably, each one of the layers of connecting links corresponds to one recirculating network topology that closes in on itself.
Monacos, Steve P.↗
Wrap-Around Worlds
Flogiston Corporation was included in Spinoff 1992 for its stress reducing chair based on data from NASA's Anthropometric Source Book. Now, under a NASA SBIR (Small Business Innovative Research), Flogiston developed a new form of immersion in virtual and video spaces called Neutral Immersion. The technology is called Flostation and is the commercial spinoff from the astronaut training system. Motorola purchased the first Flostation for testing and demonstrating a new warping chip it is developing.
Source record↗
Distributed Sensing of Composite Over-wrapped Pressure Vessel Using Fiber-Bragg Gratings at Ambient and Cryogenic Temperatures
Fiber Bragg gratings are use to monitor the structural properties of composite pressure vessels. These gratings optically inscribed into the core of a single mode fiber are used as a tool to monitor the stress strain relation in laminate structure. The fiber Bragg sensors are both embedded within the composite laminates and bonded to the surface of the vessel with varying orientations with respect to the carbon fiber in the epoxy matrix. The response of these fiber-optic sensors is investigated by pressurizing the cylinder up to its burst pressure of around 2800 psi. This is done at both ambient and cryogenic temperatures using water and liquid nitrogen. The recorded response is compared with the response from conventional strain gauge also present on the vessel. Additionally, several vessels were tested that had been damaged to simulate different type of events, such as cut tow, delimitation and impact damage.
Grant, Joseph↗
Distributed sensing of Composite Over-wrapped Pressure Vessel using Fiber-Bragg Gratings at Ambient and Cryogenic Temperatures
Fiber Bragg gratings are use to monitor the structural properties of composite pressure vessels. These gratings optically inscribed into the core of a single mode fiber are used as a tool to monitor the stress strain relation in laminate structure. The fiber Bragg sensors are both embedded within the composite laminates and bonded to the surface of the vessel with varying orientations with respect to the carbon fiber in the epoxy matrix. The response of these fiber-optic sensors is investigated by pressurizing the cylinder up to its burst pressure of around 2800 psi. This is done at both ambient and cryogenic temperatures using water and liquid nitrogen. The recorded response is compared with the response from conventional strain gauge also present on the vessel. Additionally, several vessels were tested that had been damaged to simulate different type of events, such as cut tow, delimitation and impact damage.
Grant, Joseph↗