1,670 research outputs found
Fullerenes formation in flames
Fullerenes are composed of carbon atoms arranged in approximately spherical or ellipsoidal cages resembling the geodesic domes designed by Buckminster Fuller, after whom the molecules were named. The approximately spherical fullerene, which resembles a soccer ball and contains sixty atoms (C60), is called buckminsterfullerene. The fullerene containing seventy carbon atoms (C70) is approximately ellipsoidal, similar to a rugby ball. Fullerenes were first detected in 1985, in carbon vapor produced by laser evaporation of graphite. The closed shell structure, which has no edge atoms vulnerable to reaction, was proposed to explain the observed high stability of certain carbon clusters relative to that of others at high temperatures and in the presence of an oxidizing gas
Aircraft/island/ship/satellite intercomparison: Preliminary results from July 16, 1987
The First ISCCP Regional Experiment (FIRE) objective of validating and improving satellite algorithms for inferring cloud properties from satellite radiances was one of the central motivating factors in the design of the specific field experimental strategies used in the July, 1987 marine stratocumulus intensive field observations (IFO). The in situ measuring platforms were deployed to take maximum advantage of redundant measurements (for intercomparison of the in situ sensors) and to provide optimal coverage within satellite images. One of the most ambitious of these strategies was the attempt to coordinate measurements from San Nicolas Island (SNI), the R/V Pt. Sur, the meteorological aircraft, and the satellites. For the most part, this attempt was frustrated by flight restrictions in the vicinity of SNI. The exception was the mission of July 16, 1987, which achieved remarkable success in the coordination of the platforms. This presentation concerns operations conducted by the National Center for Atmospheric Research (NCAR) Electra and how data from the Electra can be integrated with and compared to data from the Pt. Sur, SNI, and the satellites. The focus is on the large-scale, integrated picture of the conditions on July 16 from the perspective of the Electra's flight operations
Assistive Technology User Groups and Early Childhood Educators
This article explores the potential of User Groups as a professional development venue for early childhood educators in developing operational and functional competence in using hardware and software components of an Assistive Technology (AT) Toolkit. User Groups are composed of varying numbers of participants having an interest in technology, and are led by one or more skilled facilitators who meet with participants across time to help them acquire and demonstrate new technology skill sets. A series of these groups were conducted with seven early education professionals serving young preschool children who were at risk or who had disabilities. The impact of these User Groups was examined using self-reports subsequent to User Group participation. Specific data were collected regarding the types of technologies that had been used, and the types of classroom instructional products that had been created and implemented in classrooms using the technologies. A discussion of the value of User Groups is presented
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Coal plasticity at high heating rates and temperatures
The broad objective of this project is to obtain improved, quantitative understanding of the transient plasticity of bituminous coals under high heating rates and other reaction and pretreatment conditions of scientific and practical interest. To these ends the research plan is to measure the softening and resolidification behavior of two US bituminous coals with a rapid-heating, fast response, high-temperature coal plastometer, previously developed in this laboratory. Specific measurements planned for the project include determinations of apparent viscosity, softening temperature, plastic period, and resolidificationtime for molten coal: (1) as a function of independent variations in coal type, heating rate, final temperature, gaseous atmosphere (inert, 0{sub 2} or H{sub 2}), and shear rate; and (2) in exploratory runs where coal is pretreated (preoxidation, pyridine extraction, metaplast cracking agents), before heating. The intra-coal inventory and molecular weight distribution of pyridine extractables will also be measured using a rapid quenching, electrical screen heater coal pyrolysis reactor. The yield of extractables is representative of the intra-coal inventory of plasticing agent (metaplast) remaining after quenching. Coal plasticity kinetics will then be mathematically modeled from metaplast generation and depletion rates, via a correlation between the viscosity of a suspension and the concentration of deformable medium (here metaplast) in that suspension. Work during this reporting period has been concerned with re-commissioning the rapid heating rate plastometer apparatus
INTERDEPENDENT INFRASTRUCTURE RESILIENCE IN THE U.S. VIRGIN ISLANDS: PRELIMINARY ASSESSMENT
Prepared for: Federal Emergency Management AgencyThe U.S. Virgin Islands (USVI) is a territory comprised of three main islands—Saint Croix, Saint John, and Saint Thomas—and a
number of smaller surrounding islands, located in the Leeward Islands of the Lesser Antilles approximately 40 miles east of Puerto
Rico and over 1,100 miles from Miami, Florida. In September 2017, two Category-5 hurricanes made landfall within a two-week
period and collectively devastated the homes, businesses, and infrastructure throughout the Territory.This technical report (1) explains
the structure, function, and tensions associated with energy, water, transportation, and communication infrastructure that were chronic
problems prior to the hurricanes; (2) documents hurricane response, recovery, and mitigation activities for these infrastructure systems
after the hurricanes; and (3) provides concrete approaches to overcome potential barriers to resilience (where they exist) and open
questions for research (where they do not yet exist).Federal Emergency Management AgencyFederal Emergency Management AgencyApproved for public release; distribution is unlimited
Cultural Resources Investigations Along Whiteoak Bayou, Harris County, Texas
In 1986, cultural resources investigations were carried out to prepare a synthesis of the archeology of the Whiteoak Bayou area in western Harris County, Texas, and to conduct subsurface testing at prehistoric sites that may be affected by the U.S. Army Corps of Engineers Upper Whiteoak Bayou Flood Damage Reduction Project. The tasks undertaken during these investigations are: (1) background research into the environment and archeology of the area; (2) historic/archival research and reconnaissance survey to summarize the historical development of Whiteoak Bayou and to identify any important sites in the project area; (3) intensive survey of Vogel Creek, a tributary to Whiteoak Bayou, to assess the potential for intact cultural remains; (4) National Register testing and assessment of nine aboriginal sites; (5) geoarcheological investigations to establish the geological context of the archeological remains, to identify the depositional environments represented, and to establish an alluvial sequence for the project area; and (6) analysis of a large collection of artifacts from 46 Whiteoak Bayou sites made prior to 1986 by members of the Houston Archeological Society, as well as the materials recovered during 1986. The nine archeological sites tesLed during this project are 41HR241, 4lHR259, 41HR273, 41HR278, 41HR279, 41HR283, 41HR290, 41HR298, and 41HR541. The testing showed that only three -- 41HR259, 41HR273, and 41HR541 -- have substantial, intact cultural deposits. Two of these -- 41HR273 and 41HR541 -- are judged to be eligible for listing on the National Register of Historic Places and for designation as State Archeological Landmarks. One site, 4lHR259, is currently listed on the National Register, although the remaining part of this site is judged to have a limited potential to yield additi0nal information. The other seven sites are judged to be ineligible for listing
All Six Planets Known to Orbit Kepler-11 Have Low Densities
The Kepler-11 planetary system contains six transiting planets ranging in
size from 1.8 to 4.2 times the radius of Earth. Five of these planets orbit in
a tightly-packed configuration with periods between 10 and 47 days. We perform
a dynamical analysis of the system based upon transit timing variations
observed in more than three years of \ik photometric data. Stellar parameters
are derived using a combination of spectral classification and constraints on
the star's density derived from transit profiles together with planetary
eccentricity vectors provided by our dynamical study. Combining masses of the
planets relative to the star from our dynamical study and radii of the planets
relative to the star from transit depths together with deduced stellar
properties yields measurements of the radii of all six planets, masses of the
five inner planets, and an upper bound to the mass of the outermost planet,
whose orbital period is 118 days. We find mass-radius combinations for all six
planets that imply that substantial fractions of their volumes are occupied by
constituents that are less dense than rock. The Kepler-11 system contains the
lowest mass exoplanets for which both mass and radius have been measured.Comment: 39 pages, 10 figure
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