15,734 research outputs found
Alternatives to the Gypsy Moth Eradication Program in Michigan
Responding to questions of what the gypsy moth, Porthetria dispar, would do in Michigan forests, a computer simulation model was constructed. The model consisted of three subunits: a submodel of gypsy moth population dynamics, a submodel of forest growth and a submodel of tree defoliation and mortality. Several different policies were simulated for an 80 year period. The eradication policy now employed in Michigan failed due to survival of small portions of the population. Allowing the gypsy moth to become established in Michigan forests and then responding by spraying when defoliation is visible provided a policy with the least economic and environmental cost
Alternative Evaluation Procedures for South Dakota Use-Value Assessment of Agricultural Lands
Property taxes for agricultural lands continue to be a source of concern to both agricultural producers who must pay them and local units of government which depend upon this revenue. Recently attention has focused on the assessment criteria for agricultural lands. Should the assessment of agricultural lands be based on market values or productivity? If productivity is used, what estimation procedure should be used? This research bulletin puts these public affairs questions in a decision making framework. The purpose is to educate rather than to advocate a particular solution
Considerations for rollback provisions for South Dakota\u27s use-value assessment of agricultural Lands
The assessment of agricultural lands in South Dakota must be based on its use-value or productivity in agriculture rather than full market values. Suggestions have been made that the law should include rollback provisions to discourage speculative land purchases and to control urban sprawl. How effective are rollback provisions in achieving these ends? How are farm and nonfarm taxes affected by these provisions? This research bulletin develops a decision making framework for this public affair issue . The purpose is to educate rather than to advocate a particular solution
Preliminary design study of nuclear Brayton cycle/Heat Exchanger and Duct Assembly /HXDA/, phase 3 Topical report
Nuclear Brayton cycle heat exchanger and duct assembl
Large Magnetic Moments of Arsenic-Doped Mn Clusters and their Relevance to Mn-Doped III-V Semiconductor Ferromagnetism
We report electronic and magnetic structure of arsenic-doped manganese
clusters from density-functional theory using generalized gradient
approximation for the exchange-correlation energy. We find that arsenic
stabilizes manganese clusters, though the ferromagnetic coupling between Mn
atoms are found only in MnAs and MnAs clusters with magnetic moments 9
and 17 , respectively. For all other sizes, 3, 5-10,
MnAs clusters show ferrimagnetic coupling. It is suggested that, if grown
during the low temperature MBE, the giant magnetic moments due to ferromagnetic
coupling in MnAs and MnAs clusters could play a role on the
ferromagnetism and on the variation observed in the Curie temperature of
Mn-doped III-V semiconductors.Comment: 4 Pages, 3 Figures[1 EPS and 2 JPG files], RevTeX
Forestland type identification and analysis in Western Massachussetts: A linkage of a LANDSAT forest inventory to an optimization study
Digital land cover files derived from computer processing of LANDSAT and soil productivity data were linked and used by linear programming model to determine production of forested areas under different management strategies. Results of model include maps and data graphics for four-county region in Western Massachusetts
Aharonov-Bohm Radiation of Fermions
We analyze Aharonov-Bohm radiation of charged fermions from oscillating
solenoids and cosmic strings. We find that the angular pattern of the radiation
has features that differ significantly from that for bosons. For example,
fermionic radiation in the lowest harmonic is approximately isotropically
distributed around an oscillating solenoid, whereas for bosons the radiation is
dipolar. We also investigate the spin polarization of the emitted
fermion-antifermion pair. Fermionic radiation from kinks and cusps on cosmic
strings is shown to depend linearly on the ultraviolet cut-off, suggesting
strong emission at an energy scale comparable to the string energy scale.Comment: 14 pages, 6 figures. Version 2: Expanded discussion on boundary
conditions obeyed by Dirac equation mode functions (in Section V B).
Acknowledgements and references added. Version 3: Minor changes made in
response to referee's comment
Combustion of hydrogen-air jets in local chemical equilibrium: A guide to the CHARNAL computer program
A guide to a computer program, written in FORTRAN 4, for predicting the flow properties of turbulent mixing with combustion of a circular jet of hydrogen into a co-flowing stream of air is presented. The program, which is based upon the Imperial College group's PASSA series, solves differential equations for diffusion and dissipation of turbulent kinetic energy and also of the R.M.S. fluctuation of hydrogen concentration. The effective turbulent viscosity for use in the shear stress equation is computed. Chemical equilibrium is assumed throughout the flow
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