887 research outputs found
Quiet Clean Short-haul Experimental Engine (QCSEE). Core engine noise measurements
Noise measurements were taken on a turbofan engine which uses the same core, with minor modifications, employed on the quiet clean short-haul experimental engine (QCSEE) propulsion systems. Both nearfield and farfield noise measurements were taken in order to determine the core internally generated noise levels. The resulting noise measurements were compared to predicted combustor and turbine noise levels, to verify or improve the predicted QCSEE combustor and turbine noise levels
Quiet, Clean, Short-Haul Experimental Engine (QCSEE) Over-The-Wing (OTW) engine acoustic design
The acoustic considerations involved in the low source noise basic engine design and the design procedures followed in the development of the over-the-wing (OTW) nacelle acoustic treatment design are presented. Laboratory experiments, component tests, and scale model and engine tests supporting the OTW engine acoustic design are referenced. Acoustic design features include a near-sonic inlet, low fan and core pressure ratios, low fan tip speed, high and low frequency stacked core treatment, multiple thickness treatment, and fan frame and stator vane treatment
Thrust reverser design studies for an over-the-wing STOL transport
Aerodynamic and acoustics analytical studies were conducted to evaluate three thrust reverser designs for potential use on commercial over-the-wing STOL transports. The concepts were: (1) integral D nozzle/target reverser, (2) integral D nozzle/top arc cascade reverser, and (3) post exit target reverser integral with wing. Aerodynamic flowpaths and kinematic arrangements for each concept were established to provide a 50% thrust reversal capability. Analytical aircraft stopping distance/noise trade studies conducted concurrently with flow path design showed that these high efficiency reverser concepts are employed at substantially reduced power settings to meet noise goals of 100 PNdB on a 152.4 m sideline and still meet 609.6 m landing runway length requirements. From an overall installation standpoint, only the integral D nozzle/target reverser concept was found to penalize nacelle cruise performance; for this concept a larger nacelle diameter was required to match engine cycle effective area demand in reverse thrust
TF34 Quiet Nacelle nearfield acoustic test results
The results of the nearfield acoustic tests conducted on the TF34 Quiet Nacelle are presented. The high fan noise suppression levels being sought (26 PNdB reduction in aft noise) necessitated the use of an extensive system of special nearfield acoustic instrumentation to properly evaluate the suppression achieved. The design, operation, and test results from each of these nearfield acoustic instrumentation systems are presented
Acoustic design of the QCSEE propulsion systems
Acoustic design features and techniques employed in the Quiet Clean Short-Haul Experimental Engine (QCSEE) Program are described. The role of jet/flap noise in selecting the engine fan pressure ratio for powered lift propulsion systems is discussed. The QCSEE acoustic design features include a hybrid inlet (near-sonic throat velocity with acoustic treatment); low fan and core pressure ratios; low fan tip speeds; gear-driven fans; high and low frequency stacked core noise treatment; multiple-thickness treatment; bulk absorber treatment; and treatment on the stator vanes. The QCSEE designs represent and anticipated acoustic technology improvement of 12 to 16 PNdb relative to the noise levels of the low-noise engines used on current wide-body commercial jet transport aircraft
The Oyster River Culvert Analysis Project
Studies have already detected intensification of precipitation events consistent with climate change projections. Communities may have a window of opportunity to prepare, but information sufficiently quantified and localized to support adaptation programs is sparse: published literature is typically characterized by general resilience building or regional vulnerability studies. The Fourth Assessment Report of the IPCC observed that adaptation can no longer be postponed pending the effective elimination of uncertainty. Methods must be developed that manage residual uncertainty, providing community leaders with decision-support information sufficient for implementing infrastructure adaptation programs. This study developed a local-scale and actionable protocol for maintaining historical risk levels for communities facing significant impacts from climate change and population growth. For a coastal watershed, the study assessed the capacity of the present stormwater infrastructure capacity for conveying expected peak flow resulting from climate change and population growth. The project transferred coupled-climate model projections to the culvert system, in a form understandable to planners, resource managers and decision-makers; applied standard civil engineering methods to reverse-engineer culverts to determine existing and required capacities; modeled the potential for LID methods to manage peak flow in lieu of, or combination with, drainage system upsizing; and estimated replacement costs using local and national construction cost data. The mid-21st century, most likely 25-year, 24-hour precipitation is estimated to be 35% greater than the TP-40 precipitation for the SRES A1b trajectory, and 64% greater than the TP-40 value for the SRES A1fi trajectory. 5% of culverts are already undersized for the TP-40 event to which they should have been designed. Under the most likely A1b trajectory, an additional 12% of culverts likely will be undersized, while under the most likely A1fi scenario, an additional 19% likely will be undersized. These conditions place people and property at greater risk than that historically acceptable from the TP-4025-year design storm. This risk level may be maintained by a long-term upgrade program, utilizing existing strategies to manage uncertainty and costs. At the upper-95% confidence limit for the A1fi 25-year event, 65% of culverts are adequately sized, and building the remaining 35%, and planned, culverts to thrice the cross-sectional area specified from TP-40 should provide adequate capacity through this event. Realizable LID methods can mitigate significant impacts from climate change and population growth, however effectiveness is limited for the more pessimistic climate change projections. Results indicate that uncertainty in coupled-climate model projections is not an impediment to adaptation. This study makes a significant contribution toward the generation of reliable and specific estimates of impacts from climate change, in support of programs to adapt civil infrastructures. This study promotes a solution to today\u27s arguably most significant challenge in civil infrastructure adaptation: translating the extensive corpus of adaptation theory and regional-scale impacts analyses into localscale action
Quiet, Clean, Short-Haul, Experimental Engine (QCSEE) Under-The-Wing (UTW) engine acoustic design
The acoustic considerations involved in the low source noise basic engine design and the design procedures followed in the development of the under-the-wing (UTW) engine boilerplate and composite nacelle acoustic treatment designs are presented. Laboratory experiments, component tests, and scale model and engine tests supporting the UTW engine acoustic design are referenced. Acoustic design features include a near-sonic inlet, low fan and core pressure ratios, low fan tip speed, high and low frequency stacked core treatment, multiple thickness treatment, and fan frame and stator vane treatment
Impairment of Methotrexate Transport Is Common in Osteosarcoma Tumor Samples
Osteosarcoma does not respond well to conventional dose methotrexate but does respond to high-dose methotrexate. Previous work has indicated that this resistance may be due to impaired transport of methotrexate across the cell membrane. In this study, the PT430 competitive displacement assay was adapted to evaluate methotrexate transport in 69 high-grade osteosarcoma tumor samples. All samples studied were shown to have relatively impaired methotrexate transport by PT430 assay. Ninety-nine percent of the samples had less than 20% PT430 displacement by methotrexate. Eighty-eight percent exhibited displacement by methotrexate at less than 50% of the displacement by trimetrexate. The high frequency of impaired transport suggests the presence of decreased functionality of the reduced folate carrier protein. The overwhelming presence of impaired transport may explain why methotrexate needs to be given in high doses to be effective in osteosarcoma therapy and suggests that reduced folate carrier-independent antifolates should be explored
Naive Yearling Steers Consume Little Sericea Lespedeza in the Kansas Flint Hills
Objective: The objective of this study was to characterize diets selected by steers grazing sericea lespedeza (Lespedeza cuneata)-infested native tallgrass pastures.
Study Description: The experiment was conducted on eight native tallgrass pastures located in Woodson County, KS, at the Kansas State University Bessner Range Research Unit during the 2015 and 2016 growing season. Pastures were burned annually in April and stocked with yearling steers (n = 281/year; initial body weight = 582 ± 75 lb) at a relatively high stocking rate (2.7 acres/steer) from April 15 to July 15. Basal frequency of sericea lespedeza was 2.9 ± 2.43% during the period of our experiment.
Four 328-ft transects were laid out in a north-south gradient in each pasture. Following a 2-week adaptation period, fecal samples were collected bi-weekly from fresh fecal pats along each transect from May 1 to July 15, annually. Fecal samples were prepared and viewed under a compound microscope to identify and count plant fragment species. These data were used to determine the frequency of which plant species appeared in steer diets.
The Bottom Line: In this experiment, grasses comprised not less than 88.4% of steer diets, whereas forbs comprised not more than 11.6% of steer diets. Sericea lespedeza comprised only a minor proportion of grazing steer diets. This finding highlights the difficulty in achieving control over sericea lespedeza using grazing by yearling cattle alone
Grazing Diets of Mature Ewes in the Flint Hills Contain a Significant Proportion of Sericea Lespedeza
Objective: The objective of this study was to characterize diets selected by sheep grazing sericea lespedeza (Lespedeza cuneata) infested native tallgrass pastures and contrast these diets to those of cattle grazing the same range earlier in the grazing season. Multi-species grazing may provide an additional tool to aid landholders in the control of sericea lespedeza compared to cattle grazing only.
Study Description: The study was conducted on 8 native tallgrass pastures grazed by more than 800 mature ewes. Pastures were infested with sericea lespedeza (basal frequency = 2.9 ± 2.43%) and stocked with yearling steers at a relatively high stocking rate (2.7 acres/steer) from April 15 to July 15 and subsequently grazed by sheep from July 30 to October 1. Fecal samples were collected from individual sheep on August 15 and on September 15 for 2 years. Samples were prepared and viewed under a compound microscope to identify and count plant fragments. These data were used to determine frequency at which each plant species appeared in diets selected by freely-grazing sheep.
The Bottom Line: Sericea lespedeza comprised approximately 1.5% of sheep diets. Consumption at that level is likely sufficient to control seed production by that plant. Grazing of small ruminants in addition to cattle in a grazing system may provide landholders an additional tool for control of sericea lespedeza
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