3,374 research outputs found

    Field support, data analysis and associated research for the acoustic grenade sounding program

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    Temperature and horizontal winds in the 30 to 90 km altitude range of the upper atmosphere, were determined by acoustic grenade soundings conducted at Wallops Island, Virginia and Kourou, French Guiana. Field support provided at these locations included deployment of the large area microphone system, supervision, maintenance and operation of sound ranging stations; and coordination of activities. Data analysis efforts included the analysis of field data to determine upper atmospheric meteorological parameters. Profiles for upper atmospheric temperature, wind and density are provided in plots and tables for each of the acoustic grenade soundings conducted during the contract period. Research efforts were directed toward a systematic comparison of temperature data from acoustic grenade with other meteorological sensor probes in the upper atmosphere

    Vortex Washboard Voltage Noise in Type-II Superconductors

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    In order to characterize flux flow through disordered type-II superconductors, we investigate the effects of columnar and point defects on the vortex velocity / voltage power spectrum in the driven non-equilibrium steady state. We employ three-dimensional Metropolis Monte Carlo simulations to measure relevant physical observables including the force-velocity / current-voltage (I-V) characteristics, vortex spatial arrangement and structure factor, and mean flux line radius of gyration. Our simulation results compare well to earlier findings and physical intuition. We focus specifically on the voltage noise power spectra in conjunction with the vortex structure factor in the presence of weak columnar and point pinning centers. We investigate the vortex washboard noise peak and associated higher harmonics, and show that the intensity ratios of the washboard harmonics are determined by the strength of the material defects rather than the type of pins present. Through varying columnar defect lengths and pinning strengths as well as magnetic flux density we further explore the effect of the material defects on vortex transport. It is demonstrated that the radius of gyration displays quantitatively unique features that depend characteristically on the type of material defects present in the sample.Comment: Latex, 17 pages, 14 figure

    Mississippi timber removals - A ten year presentation

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    Mississippi is a major producer of manufactured forest products, and most of the timber required by Mississippi\u27s forest industry is produced and harvested within the State. A severance tax on timber harvested in Mississippi is paid to the Mississippi State Tax Commission, and annual reports of timber removals are prepared by the Commission

    Mississippi\u27s Severance Tax And Forest Resource Development Program

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    Mississippi\u27s Forest Resource Development Pro- gram was the second state-sponsored forestry assistance pro- gram in the United States. It was authorized by the legislature tn 1974 in response to concerns over long-term availability of softwood timber. It is funded by a severance tax levied at the potnt of first processing. Since inception, 152,295 acres have been treated under the program. Severance tax rates were established in 1974 and remained constant until 1981. Costs rose rapidly during these years, and the only way to increase funds for the program was to cut more timber or raise the fixed tax rates, as was done in 1981. Such problems would be avoided •f severance taxes were levied on the basis of current product value

    Timber severance taxes in Mississippi

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    Timber severance tax collections exceeded 2 million dollars in 1978 and 1979. Severance tax revenues are divided 25% to the state\u27s general fund, 25% to the county where the tax was collected, and 50% to support the forest resource development program.. AU severance tax rates are fixed on a per unit volume basis except on poles, piling, and post: which are taxed on a percentage of value basis

    Discount Rates for Nonindustrial Private Forest Landowners in Mississippi: How High a Hurdle?

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    Mississippi forest landowners were surveyed to determine average discount rates or “hurdle rates”—the lowest rates of return they consider acceptable—for 3 nonforestry investments, and for 5, 15, and 25 yr forestry investments. The survey included 829 individuals who owned at least 20 ac of uncultivated land and had harvested timber during a recent 5 yr period; survey results are therefore oriented toward commercially active forest landowners. On average, the private nonindustrial forest landowners included in the survey expect timberland investments to earn higher rates of compound interest than relatively low-risk bank savings accounts and certificates of deposit. Relatively short-term (5 yr) timberland investments, however, have lower minimum rates of return than stocks, bonds, and mutual funds. With forestry investments, all else equal, Mississippi nonindustrial private forest landowners prefer shorter time periods—average hurdle rates in nominal terms before taxes were 8.0% for forestry investments lasting 5 yr, 11.3% for those lasting 15 yr, and 13.1% for those lasting 25 yr. Household income significantly influenced the lowest rate of return considered acceptable for 5 yr forestry investments—the rate was 9% for landowners with annual incomes above 50,000and7.450,000 and 7.4% for landowners with annual incomes below 50,000. On a hurdle rate basis, higher income private landowners in Mississippi generally find forestry investments lasting 15 yr to be competitive with stocks, bonds, and mutual funds. However, Mississippi landowners’ 13.1% required rate of return for 25 yr forestry investments was higher than the rate considered acceptable for the other investments included in the survey. Reforestation tax incentives, cost-shares, and related public policies that reduce the front-end costs incurred by NIPF landowners tend to increase the projected rate of return for relatively long-term reforestation investments. South. J. Appl. For. 26(1):26–31
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