Assembly Time Estimation: Assembly Mate Based Structural Complexity Metric Predictive Modeling

This paper presents an automated tool for estimating assembly times of products based on a three step process: connectivity graph generation from assembly mate information, structural complexity metric analysis of the graph, and application of the complexity metric vector to predictive artificial neural network models. The tool has been evaluated against different training set cases, suggesting that partially defined assembly models and training product variety are critical characteristics. Moreover, the tool is shown to be robust and insensitive to different modeling engineers. The tool has been implemented in a commercial CAD system and shown to yield results of within ±25% of predicted values. Additional extensions and experiments are recommended to improve the tool

A TEST OF FOOD PARTITIONING BETWEEN THE AQUATIC LARVAE OF TWO PARAPATRIC SPECIES OF TWO-LINED SALAMANDER (EURYCEA BISLINEATA SPECIES COMPLEX) IN A ZONE OF SYMPATRIC CONTACT

Phylogenetically related species with similar ecologies often partition resources when in sympatry. Food is an important factor in the co-occurrence of sympatric salamanders, and food partitioning occurs in a variety of sympatric, similar species. Several members of the Two-lined Salamander (Eurycea bislineata) species complex are largely parapatric but co-exist within a narrow zone of sympatric contact. Because larvae of these salamanders frequently occur in very high densities, we tested the hypothesis that larvae of the Blue Ridge Salamander (E. wilderae) and the Southern Two-lined Salamander (E. cirrigera) partition food in sympatry in northeastern Georgia. We predicted that the diets of these two species would differ in sympatry and that the respective diet of each species would differ between allopatric and sympatric populations. Both species fed largely on the aquatic larvae of Trichoptera and Diptera, and their diets reflected the available insect fauna of the respective streams. There was no significant difference between the species in sympatry or between allopatric and sympatric populations of either species. Although we found no evidence of food partitioning, we cannot rule out interspecific competition that may manifest itself in some resource other than food

The Influence of Rising Atmospheric CO\u3csub\u3e2\u3c/sub\u3e on Grassland Ecosystems

Increasing atmospheric CO2 concentrations and climatic change will have significant effects on the ecology of grasslands. This paper evaluates results from four CO2 enrichment studies in contrasting grasslands. A Swiss study investigates the effects of elevated CO2 (600 μL L-1 CO2) on perennial ryegrass (Lolium perenne L.) and white clover (Trifolium repens L), a New Zealand study examines how elevated CO2 (475 μL L-1 CO2) affects a botanically diverse pasture, and studies in the Kansas tallgrass prairie and the Colorado shortgrass steppe investigate the effects of an approximate doubling of CO2 in native grasslands. Productivity in all four grasslands was enhanced at elevated CO2, with the largest relative increases occurring in dry years on the shortgrass steppe (71%) and on the tallgrass prairie (36%). Nitrogen additions, whether from fertilizer or legumes, enhanced the capability of these grasslands to respond to CO2, and legumes were among the most competitive plant types in the Swiss and New Zealand grasslands under elevated CO2. No evidence was found to support the notion that C3 grasses were more competitive under elevated CO2 compared to C4 grasses. The results suggest that CO2 enrichment and global warming will have important impacts on grasslands

Effect of Burning and Clipping on Big Bluestem Reserve Carbohydrates

Carbohydrate content of rhizomes and stem bases of big bluestem (Andropogon gerardi Vitman) at different times during the growing season were measured on plots with different clipping and burning treatments. Big bluestem on plots burned May 1 had higher herbage yields, percent nitrogen, and total nitrogen in forage than that on unburned plots. Rapid vegetative growth during mid-July reduced carbohydrate percentages in rhizomes and stem bases of big bluestem. Burning did not affect final storage of carbohydrate on unclipped plots, but, in general, it reduced carbohydrate reserves on clipped plots. Late season clipping reduced carbohydrate reserves more than early season clipping.This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202

Effects of One Year of Intensive Clipping on Big Bluestem

Effects of 1 year of clipping on tiller density, herbage yield, rhizome weight, rhizome nitrogen content, and rhizome total nonstructural carbohydrate content of big bluestem were investigated. We observed that as clipping frequency increased, tiller density, herbage yield, and total nonstructural carbohydrate content decreased, that recovery of rhizome nitrogen percentages was rapid under rest, and that rhizome weight was not significantly affected.This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202

Influence of mycorrhizal fungi and fertilization on big bluestem seedling biomass

The relationship between fertilization of prairie soils and mycorrhizal symbiosis in big bluestem (Andropogon gerardii Vit.) was explored. In 10 steamed prairie soils of varied P level, inoculation with a mycorrhizal fungus resulted in a 7- to 70-fold increase in big bluestem seedling biomass, compared to noninoculated controls. Fertilization with N and K (25-0-25) significantly increased biomass of mycorrhizal seedlings but did not alter growth of nonmycorrhizal seedlings. In a second experiment which assessed the impact of N and P on seedling growth, in both steamed and nonsterile soil, P fertilization did not significantly increase plant biomass, while N fertilization did substantially increase biomass of mycorrhizal, but not nonmycorrhizal plants. Fertilization with N and P together produced the greatest biomass in both mycorrhizal and nonmycorrhizal plants. Apparently, in the range soils tested N is the most limiting nutrient, despite the low P availability exhibited by these soils. In the absence of mycorrhizae, however, P is most limiting and no response to N is observed unless sufficient P is also applied. These studies confirm an extremely important role for mycorrhizal fungi on big bluestem seedling growth.This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202