Computational Analyses in Support of Sub-scale Diffuser Testing for the A-3 Facility

A unique assessment of acoustic similarity scaling laws and acoustic analogy methodologies in predicting the far-field acoustic signature from a sub-scale altitude rocket test facility at the NASA Stennis Space Center was performed. A directional, point-source similarity analysis was implemented for predicting the acoustic far-field. In this approach, experimental acoustic data obtained from "similar" rocket engine tests were appropriately scaled using key geometric and dynamic parameters. The accuracy of this engineering-level method is discussed by comparing the predictions with acoustic far-field measurements obtained. In addition, a CFD solver was coupled with a Lilley's acoustic analogy formulation to determine the improvement of using a physics-based methodology over an experimental correlation approach. In the current work, steady-state Reynolds-averaged Navier-Stokes calculations were used to model the internal flow of the rocket engine and altitude diffuser. These internal flow simulations provided the necessary realistic input conditions for external plume simulations. The CFD plume simulations were then used to provide the spatial turbulent noise source distributions in the acoustic analogy calculations. Preliminary findings of these studies will be discussed

Climate, wildfire, and erosion ensemble foretells more sediment in western USA watersheds

The area burned annually by wildfires is expected to increase worldwide due to climate change. Burned areas increase soil erosion rates within watersheds, which can increase sedimentation in downstream rivers and reservoirs. However, which watersheds will be impacted by future wildfires is largely unknown. Using an ensemble of climate, fire, and erosion models, we show that postfire sedimentation is projected to increase for nearly nine tenths of watersheds by \u3e10% and for more than one third of watersheds by \u3e100% by the 2041 to 2050 decade in the western USA. The projected increases are statistically significant for more than eight tenths of the watersheds. In the western USA, many human communities rely on water from rivers and reservoirs that originates in watersheds where sedimentation is projected to increase. Increased sedimentation could negatively impact water supply and quality for some communities, in addition to affecting stream channel stability and aquatic ecosystems

The Truth Comes From Us: Supporting Workers with Developmental Disabilities

Employment professionals play a powerful role in the pursuit of true inclusion. This paper by self-advocates outlines key steps on how allies can move people with developmental disabilities out of poverty and into the heart of our communities

The Truth Comes From Us: Supporting Workers with Developmental Disabilities

Employment professionals play a powerful role in the pursuit of true inclusion. This paper by self-advocates outlines key steps on how allies can move people with developmental disabilities out of poverty and into the heart of our communities

Considerations for Achieving Cross-Platform Point Cloud Data Fusion across Different Dryland Ecosystem Structural States

Remotely sensing recent growth, herbivory, or disturbance of herbaceous and woody vegetation in dryland ecosystems requires high spatial resolution and multi-temporal depth. Three dimensional (3D) remote sensing technologies like lidar, and techniques like structure from motion (SfM) photogrammetry, each have strengths and weaknesses at detecting vegetation volume and extent, given the instrument's ground sample distance and ease of acquisition. Yet, a combination of platforms and techniques might provide solutions that overcome the weakness of a single platform. To explore the potential for combining platforms, we compared detection bias amongst two 3D remote sensing techniques (lidar and SfM) using three different platforms [ground-based, small unmanned aerial systems (sUAS), and manned aircraft]. We found aerial lidar to be more accurate for characterizing the bare earth (ground) in dense herbaceous vegetation than either terrestrial lidar or aerial SfM photogrammetry. Conversely, the manned aerial lidar did not detect grass and fine woody vegetation while the terrestrial lidar and high resolution near-distance (ground and sUAS) SfM photogrammetry detected these and were accurate. UAS SfM photogrammetry at lower spatial resolution under-estimated maximum heights in grass and shrubs. UAS and handheld SfM photogrammetry in near-distance high resolution collections had similar accuracy to terrestrial lidar for vegetation, but difficulty at measuring bare earth elevation beneath dense herbaceous cover. Combining point cloud data and derivatives (i.e., meshes and rasters) from two or more platforms allowed for more accurate measurement of herbaceous and woody vegetation (height and canopy cover) than any single technique alone. Availability and costs of manned aircraft lidar collection preclude high frequency repeatability but this is less limiting for terrestrial lidar, sUAS and handheld SfM. The post-processing of SfM photogrammetry data became the limiting factor at larger spatial scale and temporal repetition. Despite the utility of sUAS and handheld SfM for monitoring vegetation phenology and structure, their spatial extents are small relative to manned aircraft.U.S. Department of Agriculture, Agricultural Research Service [58-2022-5-13]; National Science Foundation [DBI-0735191, DBI-1265383, ACI-144506]Open access journal.This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Comparative Morbidity of Axillary Lymph Node Dissection and the Sentinel Lymph Node Technique: Implications for Patients With Breast Cancer

OBJECTIVE: To assess our long-term complications from complete axillary lymph node dissection (AXLND) in patients with breast cancer. SUMMARY BACKGROUND DATA: Complete AXLND as part of the surgical therapy for breast cancer has come under increased scrutiny due the use of the sentinel lymph node (SLN) biopsy technique to assess the status of the axillary nodes. As the enthusiasm for the SLN technique has increased, our impression has been that the perceived complication rate from AXLND has increased dramatically while the negative aspects of the SLN technique have been underemphasized. METHODS: Female patients seen in routine follow-up over a 1-year period were eligible for our retrospective study of the long-term complications from AXLND if they were a minimum of 1 year out from all primary therapy; ie, surgery, radiation, and/or chemotherapy. All patients had previously undergone either a modified radical mastectomy (MRM) or a segmental mastectomy with axillary dissection and postoperative radiation (SegAx/XRT). All patients had a Level I–III dissection. Objective measurements, including upper and lower arm circumferences and body mass index (BMI), were obtained, and a subjective evaluation from the patients was conducted. RESULTS: Ninety-four patients were eligible for our study; 44 had undergone MRM, and 50 had undergone SegAx/XRT. The average number of nodes removed was 25.6 (standard deviation, 8). Thirty-three percent of the patients had positive nodal disease, 95% of the patients had an upper arm circumference within 2 cm of the unaffected side, and 93.3% had a lower arm circumference within 2 cm of the unaffected side. Subjectively, 90.4% of the patients had either no or minimal arm swelling, and 96.8% of the patients had “good” or “excellent” overall arm function. The most common long-term symptom was numbness involving the upper, inner aspect of the affected arm (25.5%). CONCLUSIONS: Our data indicate that a complete AXLND can be performed with minimal long-term morbidity. The lower the morbidity of AXLND, the less acceptable are the unique complications of the SLN technique

Gas-Phase Reactions of Isoprene and Its Major Oxidation Products

Isoprene carries approximately half of the flux of non-methane volatile organic carbon emitted to the atmosphere by the biosphere. Accurate representation of its oxidation rate and products is essential for quantifying its influence on the abundance of the hydroxyl radical (OH), nitrogen oxide free radicals (NO_<i>x</i>), ozone (O₃), and, via the formation of highly oxygenated compounds, aerosol. We present a review of recent laboratory and theoretical studies of the oxidation pathways of isoprene initiated by addition of OH, O₃, the nitrate radical (NO₃), and the chlorine atom. From this review, a recommendation for a nearly complete gas-phase oxidation mechanism of isoprene and its major products is developed. The mechanism is compiled with the aims of providing an accurate representation of the flow of carbon while allowing quantification of the impact of isoprene emissions on HO_<i>x</i> and NO_<i>x</i> free radical concentrations and of the yields of products known to be involved in condensed-phase processes. Finally, a simplified (reduced) mechanism is developed for use in chemical transport models that retains the essential chemistry required to accurately simulate isoprene oxidation under conditions where it occurs in the atmosphereabove forested regions remote from large NO_<i>x</i> emissions