Reflection high-energy electron diffraction analysis of polycrystalline films with grain size and orientation distributions

We report a computationally efficient algorithm to calculate reflection high-energy electron diffraction (RHEED) intensities from well-textured, small-grained polycrystalline films in the kinematic limit. We also show how the intensity maps of the spots in a RHEED pattern from such a film can be quantitatively analyzed to determine the film's average grain size, as well as its in-plane orientation and texture distributions. We find that the in-plane orientation and texture distribution widths of these films can be determined to within 1 degree and that the average lateral grain size can be measured to within a fraction of a nanometer after suitable calibration of our technique

Analysis of Nitrogen Loading Reductions for Wastewater Treatment Facilities and Non-Point Sources in the Great Bay Estuary Watershed

In 2009, the New Hampshire Department of Environmental Services (DES) published a proposal for numeric nutrient criteria for the Great Bay Estuary. The report found that total nitrogen concentrations in most of the estuary needed to be less than 0.3 mg N/L to prevent loss of eelgrass habitat and less than 0.45 mg N/L to prevent occurrences of low dissolved oxygen. Based on these criteria and an analysis of a compilation of data from at least seven different sources, DES concluded that 11 of the 18 subestuaries in the Great Bay Estuary were impaired for nitrogen. Under the Clean Water Act, if a water body is determined to be impaired, a study must be completed to determine the existing loads of the pollutant and the load reductions that would be needed to meet the water quality standard. Therefore, DES developed models to determine existing nitrogen loads and nitrogen loading thresholds for the subestuaries to comply with the numeric nutrient criteria. DES also evaluated the effects of different permitting scenarios for wastewater treatment facilities on nitrogen loads and the costs for wastewater treatment facility upgrades. This modeling exercise showed that: Nitrogen loads to the Great Bay, Little Bay, and the Upper Piscataqua River need to be reduced by 30 to 45 percent to attain the numeric nutrient criteria. Both wastewater treatment facilities and non-point sources will need to reduce nitrogen loads to attain the numeric nutrient criteria. The percent reduction targets for nitrogen loads only change minimally between wet and dry years. Wastewater treatment facility upgrades to remove nitrogen will be costly; however, the average cost per pound of nitrogen removed from the estuary due to wastewater facility upgrades is lower than for non-point source controls. The permitting options for some wastewater treatment facilities will be limited by requirements to not increase pollutant loads to impaired waterbodies. The numeric nutrient criteria and models used by DES are sufficiently accurate for calculating nitrogen loading thresholds for the Great Bay watershed. Additional monitoring and modeling is needed to better characterize conditions and nitrogen loading thresholds for the Lower Piscataqua River. This nitrogen loading analysis for Great Bay may provide a framework for setting nitrogen permit limits for wastewater treatment facilities and developing watershed implementation plans to reduce nitrogen loads

Full-scale transmission testing to evaluate advanced lubricants

Experimental tests were performed on the OH-58A helicopter main rotor transmission in the NASA Lewis 500 hp helicopter transmission test stand. The testing was part of a lubrication program. The objectives are to develop and show a separate lubricant for gearboxes with improved performance in life and load carrying capacity. The goal was to develop a testing procedure to fail certain transmission components using a MIL-L-23699 based reference oil and then to run identical tests with improved lubricants and show improved performance. The tests were directed at parts that failed due to marginal lubrication from Navy field experience. These failures included mast shaft bearing micropitting, sun gear and planet bearing fatigue, and spiral bevel gear scoring. A variety of tests were performed and over 900 hrs of total run time accumulated for these tests. Some success was achieved in developing a testing procedure to produce sun gear and planet bearing fatigue failures. Only marginal success was achieved in producing mast shaft bearing micropitting and spiral bevel gear scoring

Development of a full-scale transmission testing procedure to evaluate advanced lubricants

Experimental tests were performed on the OH-58A helicopter main rotor transmission in the NASA Lewis 500-hp Helicopter Transmission Test Stand. The testing was part of a joint Navy/NASA/Army lubrication program. The objective of the program was to develop a separate lubricant for gearboxes and demonstrate an improved performance in life and load-carrying capacity. The goal of the experiments was to develop a testing procedure to fail certain transmission components using a MIL-L-23699 base reference oil, then run identical tests with improved lubricants and demonstrate performance. The tests were directed at failing components that the Navy has had problems with due to marginal lubrication. These failures included mast shaft bearing micropitting, sun gear and planet bearing fatigue, and spiral bevel gear scoring. A variety of tests were performed and over 900 hours of total run time accumulated for these tests. Some success was achieved in developing a testing procedure to produce sun gear and planet bearing fatigue failures. Only marginal success was achieved in producing mast shaft bearing micropitting and spiral bevel gear scoring

Seasonal Occurrence of the Sod Webworm Moths (Lepidoptera: Crambidae) of Ohio

While nearly 100 species of sod webworms are known to occur in North America, the species complex and seasonal occurrence of these moths has been documented in relatively few states. For Ohio, there is little published record of the sod webworm species complex, and the seasonal occurrence of only a few economically important species has been documented. Using black light traps, sod web worm adult flight activity was monitored over the course of three to five years at four different locations throughout Ohio. In this paper we report the seasonal occurrence of sod web worms species captured at these locations. These data provide a historical benchmark of sod web­worm species diversity, local abundance, and seasonal occurrence in Ohio

Bose-Einstein Correlations for Mixed Neutral Mesons

Correlations are shown to arise in nonidentical mixed-particle pairs like $K^o \bar K^o$ when observed in identical decay modes like $K_S K_S$ in multiparticle final states containing many partial waves. No enhancement is found in any single partial wave and all partial wave analyses of the s-wave threshold resonance $a_o$ and $f_o$ should give the same results for all decay modes. In CP violation experiments where $B^o - \bar B^o$ pairs are inclusively produced and correlated decays into $\psi K_S$ and leptonic modes are observed, the CP-violating lepton asymmetry is enhanced by a factor of two in the kinematic region where Bose enhancement occurs.Comment: 11 page

Reflection high-energy electron diffraction experimental analysis of polycrystalline MgO films with grain size and orientation distributions

Analysis of biaxial texture of MgO films grown by ion-beam-assisted deposition (IBAD) has been performed using a quantitative reflection high-energy electron diffraction (RHEED) based method. MgO biaxial texture is determined by analysis of diffraction spot shapes from single RHEED images, and by measuring the width of RHEED in-plane rocking curves for MgO films grown on amorphous Si3N4 by IBAD using 750 eV Ar+ ions, at 45° incidence angle, and MgO e-beam evaporation. RHEED-based biaxial texture measurement accuracy is verified by comparison with in-plane and out-of-plane orientation distribution measurements made using transmission electron microscopy and x-ray rocking curves. In situ RHEED measurements also enable the analysis of the evolution of the biaxial texture which narrows with increasing film thickness. RHEED-based measurements of IBAD MgO biaxial texture show that the minimum in-plane orientation distribution depends on the out-of-plane orientation distribution, and indicates that the minimum obtainable in-plane orientation on distribution is 2°

Complementing quantitative typology with behavioral approaches: Evidence for typological universals

Two main classes of theory have been advanced to explain correlations between linguistic features like those observed by Greenberg (1963). arbitrary constraint theories argue that certain sets of features patterm together because they have a single underlying cause in the innate language faculty (e.g., the Principles and Parameters program; see Chomsky & Lasnik 1993). functional theories argue that languages are less likely to have certain combinations of properties because, although possible in principle, they are harder to learn or to process, or less suitable for efficient communication (Hockett 1960, Bates & MacWhinney 1989, Hawkins 2004, Dryer 2007, Christiansen & Chater 2008; for further discussion see Hawkins 2007 and Jaeger & Tily 2011). The failure of Dunn, Greenhill, Levinson & Gray (2011) to find systematic feature correlations using their novel computational phylogenetic methods calls into question both of these classes of theory.Alfred P. Sloan Foundation. Fellowshi

Midnight Fire-Alarm : Descriptive March-Galop

https://digitalcommons.library.umaine.edu/mmb-ps/2355/thumbnail.jp