4,724 research outputs found
Preliminary design of graphite composite wing panels for commercial transport aircraft
Subjectively assessed practical and producible graphite/epoxy designs were subjected to a multilevel screening procedure which considered structural functions, efficiency, manufacturing and producibility, costs, maintainability, and inspectability. As each progressive screening level was reviewed, more definitive information on the structural efficiency (weight), manufacturing, and inspection procedures was established to support the design selection. The configuration features that enhance producibility of the final selected design can be used as a generic base for application to other wing panel designs. The selected panel design showed a weight saving of 25 percent over a conventional aluminum design meeting the same design requirements. The estimated cost reduction in manufacturing was 20 percent, based on 200 aircraft and projected 1985 automated composites manufacturing capability. The panel design background information developed will be used in the follow-on tasks to ensure that future panel development represents practical and producible design approaches to graphite/epoxy wing surface panels
The Benefits of Breastfeeding
It is important to educate women of childbearing age, their families, and society of the benefits that breastfeeding has over bottle-feeding and formula-feeding. The benefits of breastfeeding are in three main categories. First, the developmental, physical, emotional, and spiritual benefits of the baby will be discussed. Then the physical, emotional, and spiritual benefits for the mother will be talked about along with possible contraindications or difficulties. Finally, the financial benefits of breastfeeding over feeding an infant from the bottle will be discussed as it relates to the family and government. The goal is to persuade that breastfeeding is a superior nutritional resource and has numerous physiological, psychological and financial benefits for all members of society
Evaluation of Methods of Reducing Seed Dormancy in Switchgrass, Indiangrass, and Big Bluestem
Switchgrass, Panicun virgatum L., Indiangrass, Sorghastrum nutans Nash, and big bluestem, Andropogon gerardi Vitman, are tall, erect, native warm-season perennial grasses which in the past few years have received wide acceptance for use in the midsummer pasture establishment throughout the Great Plains. These warm-season grasses are native to the eastern part of the Great Plains and largely make up the tall grass prairie. They are well adapted to hot summer conditions and grow vigorously during July and August when the growth of cool-season grasses is slow or nil. Stand establishment and laboratory seed testing of these grasses are complicated by high levels of seed dormancy which frequently persists a year or more after seed harvest. ·Germination procedures set forth in the Association of Official Seed Analysts\u27 Rules for Testing Seeds-1970 prescribe a two-week prechill of dormant switchgrass, Indiangrass and big bluestem seed. Germination readings obtained when using the above method were low. The low germinating samples can be checked to determine actual viability and potential germination with a triphenyl tetrazolium chloride solution. Tetrazolium tests indicated that many of the seed were capable of a germination and that the switchgrass, Indiangrass, and big bluestem seed were in a temporary state of dormancy. This study was undertaken to see if pre-germination treatment(s) would reduce the seed dormancy of switchgrass, Indiangrass, and big bluestem in order to obtain maximum germination reading in the laboratory and in field plantings
Investigation of Ba, BaO, Sr and SrO Pulsed Laser-Induced Vapor Plumes in N2, O2, Microwave Discharged O2, and Vacuum at Low Laser Fluence
Ba, BaO, Sr and SrO were ablated by 248 nm laser pulses at fluences ranging from 270 mJ-/sq cm to 575 mJ-/sq cm in vacuum and in 25 mtorr atmospheres of N2, O2 and microwave-discharged O2. The spectral emissions of these plumes were compared for indications of ionization due to Ba or Sr collisions with each gas. The addition of a background gas increased the ion and neutral signature across the spectrum. SrO band emission was observed at 16,600-16,900/cm and possible BaO band emissions were observed in the 18,250-18,400/cm, 19,000-19700/cm and 19,800-20,000/cm regions. A screened plate ion probe was use to establish the ion content of the Ba plume. A time of flight study established low-pressure (1 to 35 mtorr) and low-fluence (40 to 160 mJ-/sq cm relationships on Ba(+) velocity and population. Observed ion velocities ranged from 3.1 km/sec. To 4.5 km/sec. Results indicate the addition of a background gas at pressures less than 25 mtorr quenches Ba(+) in the plume and retards the plume expansion
Cooperation: Key to Management Problems
Reprint of a 2001 publication developed for the Toledo Industrial Recreation and Employee Services Association (TIRES)
Enhancing space transportation: The NASA program to develop electric propulsion
The NASA Office of Aeronautics, Exploration, and Technology (OAET) supports a research and technology (R and T) program in electric propulsion to provide the basis for increased performance and life of electric thruster systems which can have a major impact on space system performance, including orbital transfer, stationkeeping, and planetary exploration. The program is oriented toward providing high-performance options that will be applicable to a broad range of near-term and far-term missions and vehicles. The program, which is being conducted through the Jet Propulsion Laboratory (JPL) and Lewis Research Center (LeRC) includes research on resistojet, arcjets, ion engines, magnetoplasmadynamic (MPD) thrusters, and electrodeless thrusters. Planning is also under way for nuclear electric propulsion (NEP) as part of the Space Exploration Initiative (SEI)
Richness and Abundance of Carabidae and Staphylinidae (Coleoptera), in Northeastern Dairy Pastures Under Intensive Grazing
Dairy cattle has become popular to dairy farmers in the Northeast looking for management schemes to cut production costs. Carabidae (ground beetles) and Staphylinidae (rove beetles) are indicators of habitat disturbances, such as drainage of wetlands, or grassland for grazing animals, and their monitoring could provide one measure of ecosystem sustainability if intensive management systems expand or intensify in the future. Our objective was assess the abundance and species richness of these two beetle families under intensive grazing throughout Pennsylvania, southern New York and Vermont. We collected 4365 ground beetles (83 species) and 4,027 rove beetles (79 species) by pitfall traps in three years in Pennsylvania. Nine ground beetle species, Amara aenea, Poecilus chalcites, Pterostichus melanarius, Bembidion quadrimaculatum oppositum, Amara familiaris, Poecilus lucublandus, Agonum muelleri, Bembidion obtusum and Bembidion mimus represented 80% of the Carabidae collected.
Five other species were new to Pennsylvania. Four rove beetle species, Philonthus cognatus, Meronera venustula, Amischa analis, and Philonthus various = (carbonarius), comprised 74% of the total Staphylinidae collected. Yearly distributions of the dominant species did not change significantly in the three years with A. aenea and P. cognatus being most abundant every year. A parasitic rove beetle, Aleochara tristis, was recovered for the first time in Pennsylvania and Vermont since its release in the 1960\u27s to control face fly, Musca autumnalis.
Similar results were found in New York and Vermont. We collected 1,984 ground beetles (68 species). Pterostichus melanarius was most abundant. Pterostichus vernalis was detected for the first time in the United States (Vermont). It was previously reported from Montreal, Canada. We collected 843 rove beetles (45 species). Philonthus cognatus was the most abundant rove beetle. In addition, Tachinus corticinus, previously known only from Canada, was discovered for the first time in the United States in Vermont.
Pastures in Pennsylvania were diverse, containing 14 species of forage plants and 17 weed species. Botanical composition was similar in New York and Vermont. Sixteen species of grasses and legumes made up 90% of the plant composition and 36 species of weeds made up the remainder. This diverse plant ecosystem may explain the richness of ground and rove beetles in northeastern U.S. pastures because the heterogeneity in the plant population provided additional resources which can support a rich assemblage of beetles. Monitoring richness and abundance of Carabidae and Staphylinidae over three years in Pennsylvania suggests intensive grazing systems are ecologically sustainable
Impact detection system
In an embodiment, an apparatus and method capable of determining the time and location of a projectile's impact is disclosed. In another embodiment, an apparatus and method capable of determining the time and location of a projectile's impact as well as the direction from whence the projectile came is disclosed
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