190 research outputs found

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

    Get PDF
    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

    Delayed winter supplemental feeding and year-round mineral supplementation of beef cows on native range

    Get PDF
    Polled Hereford cows on native Flint Hills pasture not supplemented until February lost more weight from December to February, lost less from February to May, and were in poorer condition before calving than cows supplemented beginning in November. But calf survival, birth weight, and calf average daily gain were similar for both groups. Feeding cows a calcium, phosphorus, trace mineral mix did not improve any measure of cow or calf performance

    Response of yearling steers to burning and fertilizing pasture and intensive early season stocking (bluestem pastures)

    Get PDF
    Nine pastures totaling 492 acres were summer grazed by yearling Hereford, Hereford-Angus cross, and Angus steers distributed equally by breed. Five pastures were burned April 22, 1975; four were not burned. Burned and nonburned pastures had 0, 40, or 80 lbs. of nitrogen per acre applied aerially April 29, 1975. Stocking rates were determined with herbage production data from experimental plots under similar treatments. Under equal fertilization and stocking ratios, burned and fertilized pastures produced as much or more average daily gain and more gain per acre than nonburned pastures. Fertilizing and heavier stocking tended to reduce average daily gains but increased gains per acre. Steers on the early season, intensely-stocked pasture gained the most per day (1.78 lbs.) and produced the highest gain per acre (70 lbs.)

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

    Get PDF
    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

    Increasing levels of grain supplementation for intensive-early stocked steers: three-year summary

    Get PDF
    During the initial 3 years of a 4-year experiment, average daily gain tended to increase in direct proportion to increasing levels of grain sorghum supplementation (2.3, 2.5 and 2.7 lb gain per day for the control and 2 and 4 lb supplement per day, respectively). The amount of grass remaining in the pastures at the end of the growing season (October 1) was greater in each of the 3 years when cattle were supplemented at 4 lb/day. During the 2 years (1989 and 1990) that feedlot performance was monitored, level of supplementation for grazing steers did not influence subsequent feedlot gain or efficiency

    Nitrogen limitation constrains sustainability of ecosystem response to CO2

    Full text link
    Enhanced plant biomass accumulation in response to elevated atmospheric CO2 concentration could dampen the future rate of increase in CO2 levels and associated climate warming. However, it is unknown whether CO2-induced stimulation of plant growth and biomass accumulation will be sustained or whether limited nitrogen (N) availability constrains greater plant growth in a CO2-enriched world(1-9). Here we show, after a six-year field study of perennial grassland species grown under ambient and elevated levels of CO2 and N, that low availability of N progressively suppresses the positive response of plant biomass to elevated CO2. Initially, the stimulation of total plant biomass by elevated CO2 was no greater at enriched than at ambient N supply. After four to six years, however, elevated CO2 stimulated plant biomass much less under ambient than enriched N supply. This response was consistent with the temporally divergent effects of elevated CO2 on soil and plant N dynamics at differing levels of N supply. Our results indicate that variability in availability of soil N and deposition of atmospheric N are both likely to influence the response of plant biomass accumulation to elevated atmospheric CO2. Given that limitations to productivity resulting from the insufficient availability of N are widespread in both unmanaged and managed vegetation(5,7-9), soil N supply is probably an important constraint on global terrestrial responses to elevated CO2.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62769/1/nature04486.pd

    A class-wide phylogenetic assessment of Dothideomycetes

    Get PDF
    We present a comprehensive phylogeny derived from 5 genes, nucSSU, nucLSU rDNA, TEF1, RPB1 and RPB2, for 356 isolates and 41 families (six newly described in this volume) in Dothideomycetes. All currently accepted orders in the class are represented for the first time in addition to numerous previously unplaced lineages. Subclass Pleosporomycetidae is expanded to include the aquatic order Jahnulales. An ancestral reconstruction of basic nutritional modes supports numerous transitions from saprobic life histories to plant associated and lichenised modes and a transition from terrestrial to aquatic habitats are confirmed. Finally, a genomic comparison of 6 dothideomycete genomes with other fungi finds a high level of unique protein associated with the class, supporting its delineation as a separate taxon
    corecore