7,261 research outputs found
Light airplane crash tests at three roll angles
Three similar twin engine general aviation airplanes were crash tested at the Langley impact dynamics research facility at 27 m/sec and at nominal roll angles of 0 deg, -15 deg, and -30 deg. Other flight parameters were held constant. The test facility, instrumentation, test specimens, and test method are briefly described. Structural damage and accelerometer data for each of the three impact conditions are presented and discussed
Ammonia emissions from livestock production in Chile: an inventory and uncertainty analysis
Indexación: Web of Science; Scielo.The objective of this work was to quantify the country's NH3 emissions from livestock production. This calculation was based on the mass flow of total ammoniacal nitrogen (TAN). The analysis was performed for all 15 geographical regions in Chile. The definition of livestock subcategories was based on data from the Chilean Agriculture and Forestry Census as well as technical reports published by the Chilean National Statistics Institute. Significant differences were observed among the sources of livestock emissions in Chile's regions, and there was high variability depending on the degree of livestock confinement. In 2013, the total calculated emissions were 69.1 kt NH3/year (± 31.1). The O’Higgins Region had the highest NH3 emissions in Chile, representing 45% of the total. In terms of livestock production, 45% of the emissions were generated by pigs, 22% by poultry, 16% by cattle, 11% by equines and 4% by sheep. Emissions from the TAN that was available during manure and slurry management and the degree of animal confinement were the primary sources of uncertainty. This uncertainty could be greatly reduced by developing regional emission factors and by including the degree of animal confinement in Chile's national statistics such as the Agriculture, Livestock and Forestry Census.http://www.scielo.cl/scielo.php?pid=S0718-95162016005000005&script=sci_abstrac
Light airplane crash tests at three flight-path angles
Three similar twin engine general aviation airplane specimens were crash tested at Langley impact dynamics research facility at 27 m/sec and at flight-path angles of -15 deg, -30 deg, and -45 deg. Other flight parameters were held constant. The test facility, instrumentation, test specimens, and test method are briefly described. Structural damage and accelerometer data for each of the three impact conditions are presented and discussed
Crash tests of three identical low-wing single-engine airplane
Three identical four place, low wing single engine airplane specimens with nominal masses of 1043 kg were crash tested under controlled free flight conditions. The tests were conducted at the same nominal velocity of 25 m/sec along the flight path. Two airplanes were crashed on a concrete surface (at 10 and 30 deg pitch angles), and one was crashed on soil (at a -30 deg pitch angle). The three tests revealed that the specimen in the -30 deg test on soil sustained massive structural damage in the engine compartment and fire wall. Also, the highest longitudinal cabin floor accelerations occurred in this test. Severe damage, but of lesser magnitude, occurred in the -30 deg test on concrete. The highest normal cabin floor accelerations occurred in this test. The least structural damage and lowest accelerations occurred in the 10 deg test on concrete
The Large- Limit of the Two-Hermitian-matrix model by the hidden BRST method
This paper discusses the large N limit of the two-Hermitian-matrix model in
zero dimensions, using the hidden BRST method. A system of integral equations
previously found is solved, showing that it contained the exact solution of the
model in leading order of large .Comment: 19 pages, Latex,CERN--TH-6531/9
Development of an energy-absorbing passenger seat for a transport aircraft
Commercial air transport passenger safety and survivability, in the event of an impact-survivable crash, are subjects receiving increased technical focus/study by the aviation community. A B-720 aircraft, highly instrumented, and remotely controlled from the ground by a pilot in a simulated cockpit, was crashed on a specially prepared gravel covered impact site. The aircraft was impacted under controlled conditions in an air-to-ground gear-up mode, at a nominal speed of 150 knots and 4-1/2 deg glide slope. Data from a number of on board, crash worthiness experiments provided valuable information related to structural loads/failure modes, antimisting kerosene fuel, passenger and attendant restraint systems and energy absorbing seats. The development of an energy absorbing (EA) seat accomplished through innovative modification of a typical modern standard commercial aviation transport, three passenger seat is described
A phylogenomic perspective on the radiation of ray-finned fishes based upon targeted sequencing of ultraconserved elements
Ray-finned fishes constitute the dominant radiation of vertebrates with over
30,000 species. Although molecular phylogenetics has begun to disentangle major
evolutionary relationships within this vast section of the Tree of Life, there
is no widely available approach for efficiently collecting phylogenomic data
within fishes, leaving much of the enormous potential of massively parallel
sequencing technologies for resolving major radiations in ray-finned fishes
unrealized. Here, we provide a genomic perspective on longstanding questions
regarding the diversification of major groups of ray-finned fishes through
targeted enrichment of ultraconserved nuclear DNA elements (UCEs) and their
flanking sequence. Our workflow efficiently and economically generates data
sets that are orders of magnitude larger than those produced by traditional
approaches and is well-suited to working with museum specimens. Analysis of the
UCE data set recovers a well-supported phylogeny at both shallow and deep
time-scales that supports a monophyletic relationship between Amia and
Lepisosteus (Holostei) and reveals elopomorphs and then osteoglossomorphs to be
the earliest diverging teleost lineages. Divergence time estimation based upon
14 fossil calibrations reveals that crown teleosts appeared ~270 Ma at the end
of the Permian and that elopomorphs, osteoglossomorphs, ostarioclupeomorphs,
and euteleosts diverged from one another by 205 Ma during the Triassic. Our
approach additionally reveals that sequence capture of UCE regions and their
flanking sequence offers enormous potential for resolving phylogenetic
relationships within ray-finned fishes
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