1,138 research outputs found
Chicago Board of Trade Ethanol Contract Efficiency
Firms producing ethanol may find management of the price risk associated with production of this leading alternative fuel a key factor to continued success. As with other agricultural commodities, the influence and ability of futures contracts to serve as a risk management tool deserves attention.contract efficiency, ethanol, futures contracts, Crop Production/Industries, Risk and Uncertainty, Q13, Q43, M31,
Cathodic Protection Deployment on Space Shuttle Solid Rocket Boosters
Corrosion protection of the space shuttle solid rocket boosters incorporates the use of cathodic protection(anodes) in concert with several coatings systems. The SRB design has large carbon/carbon composites(motor nozzle) electrically connected to an aluminum alloy structure. Early in the STS program, the aluminum structures incurred tremendous corrosive attack due primarily to the galvanic couple to the carbon/carbon nozzle at coating damage locations. Also contributing to the galvanic corrosion problem were stainless steel and titanium alloy components housed within the aluminum structures and electrically connected to the aluminum structures. This paper will highlight the evolution in the protection of the aluminum structures, providing historical information and summary data from the operation of the corrosion protection systems. Also, data and information will be included regarding the evaluation and deployment of inorganic zinc rich primers as anode area on the aluminum structures
Clementine Observations of the Zodiacal Light and the Dust Content of the Inner Solar System
Using the Moon to occult the Sun, the Clementine spacecraft used its
navigation cameras to map the inner zodiacal light at optical wavelengths over
elongations of 3-30 degrees from the Sun. This surface brightness map is then
used to infer the spatial distribution of interplanetary dust over heliocentric
distances of about 10 solar radii to the orbit of Venus. We also apply a simple
model that attributes the zodiacal light as being due to three dust populations
having distinct inclination distributions, namely, dust from asteroids and
Jupiter-family comets (JFCs), dust from Halley-type comets, and an isotropic
cloud of dust from Oort Cloud comets. The best-fitting scenario indicates that
asteroids + JFCs are the source of about 45% of the optical dust cross-section
seen in the ecliptic at 1 AU, but that at least 89% of the dust cross-section
enclosed by a 1 AU radius sphere is of a cometary origin. When these results
are extrapolated out to the asteroid belt, we find an upper limit on the mass
of the light-reflecting asteroidal dust that is equivalent to a 12 km asteroid,
and a similar extrapolation of the isotropic dust cloud out to Oort Cloud
distances yields a mass equivalent to a 30 km comet, although the latter mass
is uncertain by orders of magnitude.Comment: To be published in Icaru
All-optical steering of light via spatial Bloch oscillations in a gas of three-level atoms
A standing-wave control field applied to a three-level atomic medium in a
planar hollow-core photonic crystal waveguide creates periodic variations of
linear and nonlinear refractive indexes of the medium. This property can be
used for efficient steering of light. In this work we study, both analytically
and numerically, the dynamics of probe optical beams in such structures. By
properly designing the spatial dependence of the nonlinearity it is possible to
induce long-living Bloch oscillations of spatial gap solitons, thus providing
desirable change in direction of the beam propagation without inducing
appreciable diffraction. Due to the significant enhancement of the
nonlinearity, such self-focusing of the probe beam can be reached at extremely
weak light intensities.Comment: 8 pages, 4 figure
Advancing Benchmarks for Genome Sequencing
Several recent benchmarking efforts provide reference datasets and samples to improve genome sequencing and calling of germline and somatic mutations
Silicon-on ceramic process: Silicon sheet growth and device development for the large-area silicon sheet task of the low-cost solar array project
The technical feasibility of producing solar-cell-quality sheet silicon to meet the Department of Energy (DOE) 1986 overall price goal of $0.70/watt was investigated. With the silicon-on-ceramic (SOC) approach, a low-cost ceramic substrate is coated with large-grain polycrystalline silicon by unidirectional solidification of molten silicon. This effort was divided into several areas of investigation in order to most efficiently meet the goals of the program. These areas include: (1) dip-coating; (2) continuous coating designated SCIM-coating, and acronym for Silicon Coating by an Inverted Meniscus (SCIM); (3) material characterization; (4) cell fabrication and evaluation; and (5) theoretical analysis. Both coating approaches were successful in producing thin layers of large grain, solar-cell-quality silicon. The dip-coating approach was initially investigated and considerable effort was given to this technique. The SCIM technique was adopted because of its scale-up potential and its capability to produce more conventiently large areas of SOC
Achieving Innovation and Affordability Through Standardization of Materials Development and Testing
The successful expansion of development, innovation, and production within the aeronautics industry during the 20th century was facilitated by collaboration of government agencies with the commercial aviation companies. One of the initial products conceived from the collaboration was the ANC-5 Bulletin, first published in 1937. The ANC-5 Bulletin had intended to standardize the requirements of various government agencies in the design of aircraft structure. The national space policy shift in priority for NASA with an emphasis on transferring the travel to low earth orbit to commercial space providers highlights an opportunity and a need for the national and global space industries. The same collaboration and standardization that is documented and maintained by the industry within MIL-HDBK-5 (MMPDS-01) and MIL-HBDK-17 (nonmetallic mechanical properties) can also be exploited to standardize the thermal performance properties, processing methods, test methods, and analytical methods for use in aircraft and spacecraft design and associated propulsion systems. In addition to the definition of thermal performance description and standardization, the standardization for test methods and analysis for extreme environments (high temperature, cryogenics, deep space radiation, etc) would also be highly valuable to the industry. Its subsequent revisions and conversion to MIL-HDBK-5 and then MMPDS-01 established and then expanded to contain standardized mechanical property design values and other related design information for metallic materials used in aircraft, missiles, and space vehicles. It also includes guidance on standardization of composition, processing, and analytical methods for presentation and inclusion into the handbook. This standardization enabled an expansion of the technologies to provide efficiency and reliability to the consumers. It can be established that many individual programs within the government agencies have been overcome with development costs generated from these nonstandard requirements. Without industry standardization and acceptance, the programs are driven to shoulder the costs of determining design requirements, performance criteria, and then material qualification and certification. A significant investment that the industry could make to both reduce individual program development costs and schedules while expanding commercial space flight capabilities would be to invest in standardizing material performance properties for high temperature, cryogenic, and deep space environments for both metallic and nonmetallic materials
Localized Coating Removal Using Plastic Media Blasting
USBI, a Division of United Technologies/ is responsible for the assembly, checkout and refurbishment of the structural, guidance and recovery components of the Solid Rocket Booster (SRB) as part of the NASA Space Transportation system/ Space Shuttle. The work is performed at Kennedy Space Center/ Florida and the contract is administered by Marshall Space Flight Center (MSFC) in Huntsville/ Alabama. Figure 1 shows the SRB and associated hardware that USBI is responsible for. Recently/ a considerable effort was made to qualify the use of Plastic Media Blasting (PMB) for safely and effectively removing paint and other coatings from SRB aluminum structures. As a result of the effort an improvement was made in the design of surface finishing equipment for processing flight hardware/ in addition to a potentially patentable idea on improved plastic media composition
Origins of Solar System Dust Beyond Jupiter
The measurements of cosmic interplanetary dust by the instruments on board the Pioneer 10 and 11 spacecraft contain the dynamical signature of dust generated by Edgeworth-Kuiper Belt objects, as well as short period Oort Cloud comets and short period Jupiter family comets. While the dust concentration detected between Jupiter and Saturn is mainly due to the cometary components, the dust outside Saturn's orbit is dominated by grains originating from the Edgeworth-Kuiper Belt. In order to sustain a dust concentration that accounts for the Pioneer measurements, short period external Jupiter family comets, on orbits similar to comet 29P/Schwassmann-Wachmann-1, have to produce of dust grains with sizes between 0.01 and . A sustained production rate of has to be provided by short period Oort cloud comets on 1P/Halley-like orbits. The comets can not, however, account for the dust flux measured outside Saturn's orbit. The measurements there can only be explained by a generation of dust grains in the Edgeworth-Kuiper belt by mutual collisions of the source objects and by impacts of interstellar dust grains onto the objects' surfaces. These processes have to release in total of dust from the Edgeworth Kuiper belt objects in order to account for the amount of dust found by Pioneer beyond Saturn, making the Edgeworth-Kuiper disk the brightest extended feature of the Solar System when observed from afar
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