Validation of a Transient 3-D CFD Mars Rotorcraft Performance Simulation Using Experimental Data

Given the success of NASA/JPL’s Ingenuity helicopter, the study of Martian flight vehicles and their aerodynamic characteristics has become a rapidly growing field of research. At NASA Ames, the "Rotor Optimization for the Advancement of Mars eXploration" (ROAMX) team and their partners have published designs for an advanced, second generation Mars helicopter - the "Mars Science Helicopter" (MSH) - which possesses a novel rotor geometry. This paper presents the independent development and validation of a numerical model for assessing Mars rotorcraft performance, which uses an MSH-inspired rotor as the primary research artifact. Performing Mars-analogous or exact recreations of Mars environmental conditions on Earth is both a costly and difficult technical challenge. Therefore, a transient, 3-D unsteady Reynolds-Averaged Navier Stokes (RANS) CFD model is proposed to estimate the performance of an MSH-inspired rotor in Earth atmospheric conditions. The experimental data presented in this paper corresponds to a sweep of collectives for a 75% span rotor Reynolds numbers of 2.87*10^5. The numerical simulations use the results of the experimental campaign to validate the accuracy and fidelity of the model. Delayed Detached Eddy Simulations (DDES) and a computationally cheaper steady-state RANS approach were validated using experimental data at low thrust conditions. Then, the RANS approach was used to sweep different collective pitch angles for both nominal and modified twist geometries that attempt to account for aeroelastic deformations using low-fidelity modeling. The blades with a modified twist show an improved agreement with the experimental data, with errors of about 5% in the thrust and torque coefficients for low collectives. For large collective angles, beyond which the figure of merit peaks, the RANS simulations predict premature stall compared to the experimental data. The methods and results presented in this paper are the first phase of an effort to independently estimate both the aerodynamics and dynamics of such a unique rotor geometry

Detection of protection benefits for predatory fishes depends on census methodology

Marine protected areas (MPAs) are used as fisheries management and conservation tools. Well-enforced no-take zones allow the rebuilding of natural populations of exploited species; however, there is still controversy on the role of buffer zones. The effectiveness of MPAs could be underestimated, as fish population assessments depend largely on traditional methodologies that have difficulties in detecting predatory fish because of their low abundances, their patchy distribution, and their reaction to the presence of divers. The performance of different census methods was compared in assessing the protection benefits for large predatory fishes under different protection levels (i.e. no-take and buffer zones) in five Mediterranean MPAs. Specifically, conventional strip transects (CSTs, 50 × 5 m2) and tracked roaming transects combined with distance sampling (TRT + DS, variable lengths) were compared, including a series of TRT-derived estimators with variable transect lengths and fixed widths of 20, 10, and 6 m (TRT20, TRT10, and TRT6, respectively). Additionally, the effectiveness of the MPAs studied and protection levels for conserving large predatory species was evaluated. Transects covering larger areas (i.e. TRT + DS and TRT20) allowed the detection of a greater number of species and yielded more accurate estimates of density and biomass than transects of narrower fixed widths, particularly the CSTs, which were associated with the lowest richness detection capability, accuracy, and precision. On average, both no-take zones and buffer zones appeared effective for the conservation of predatory fishes, indicating that multiple protection areas were ecologically effective. Differences between MPAs were also observed, however, probably arising from both local environmental and management factors. We suggest the implementation of methodologies with larger transects for the study of large predatory fish, combined with CSTs for the rest of the fish community, in order to avoid biases in predatory population assessments, which are key indicators of MPA effectiveness

An anticorrosive magnesium/carbon nanotube composite

This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in APPLIED PHYSICS LETTERS. 92(6):63105 (2008) and may be found at https://doi.org/10.1063/1.2842411 .ArticleAPPLIED PHYSICS LETTERS. 92(6):63105 (2008)journal articl

Sunrise Chromospheric Infrared spectroPolarimeter (SCIP) for Sunrise III: Thermal-Vacuum Test of the SCIP Optical Unit

Ground-based and airborne instrumentation for astronomy IX (2022), Montreal, jul 17-22, 2022.--Proceedings of SPIE - The International Society for Optical Engineering vol. 12184 Article number 121842BThe Sunrise Chromospheric Infrared spectroPolarimeter (SCIP) is an instrument for the third flight of the Sunrise balloon-borne solar observatory planned for 2022. To verify the high spatial and spectral resolutions required in the balloon flight, the SCIP optical unit was subjected to a thermal-vacuum test in which the SCIP optical unit was installed in a vacuum chamber and was exposed to the thermal vacuum environment expected in the balloon flight. We verified the heater control performance and the temperature distribution in the SCIP optical unit in hot and cold conditions created by the shrouds in the vacuum chamber. We confirmed the optical performance, such as spatial and spectral resolution, and an air-to-vacuum difference of the optics by injecting the laser and white lights through a vacuum window.The Sunrise III balloon project is funded in Japan by the ISAS/JAXA Small Mission-of-Opportunity program for novel solar observations and JSPS KAKENHI Grant Number 18H05234 (PI: Y. Katsukawa). We would also thank the significant technical support given by the Advanced Technology Center (ATC), NAOJ. The Spanish contribution to Sunrise III has been supported by the Spanish Ministry of Science and Innovation through projects and ESP-2016-77548-C5-1-R and RTI2018-096886-B-C51 by "Centro de Excelencia Severo Ochoa" Program under grant SEV-2017-0709. D.O.S. also acknowledges financial support through the Ramon y Cajal fellowship. The German contribution to Sunrise III is funded by the Max Planck Foundation, the Strategic Innovations Fund of the President of the Max Planck Society (MPG), the Deutsches Zentrum fur Luft und Raumfahrt (DLR), and private donations by supporting members of the Max Planck Society, which is gratefully acknowledged.Peer reviewe

Effects of treated wastewater irrigation on the establishment of young grapevines

Irrigation with treated wastewater could produce excessive accumulations within the plant and soil, negatively affecting the yield and production quality. In addition, the presence of biological and chemical contaminants could harm the agricultural environment, as well as the health of farmers and consumers. During this work, the suitability of secondary and tertiary treated wastewater for use in young grapevines was evaluated by studying the effect of the wastewater irrigation on the soil-plant system, crop yield, fruit quality and the presence of inorganic chemical contamination (salts, elements and heavy metals), organic chemical contamination (polycyclic aromatic hydrocarbons) and microbial contamination (E. coli, total coliforms). The results show that tertiary treated wastewater had positive impact on plant growth and yield while secondary treated wastewater had negative impact on fruit safety in comparison with tap water. Sodium levels in soils irrigated with treated wastewater increased at the end of the irrigation period while decreased during the wet season. The total polycyclic aromatic hydrocarbon concentrations in the soils ranged from 363 μg/kg to 374 μg/kg at the end of the experiment for all irrigation treatments applied. The use of tertiary treated wastewater was recommended for the irrigation of young grapevines as an alternative water source secured protection of environment, plant health and fruit quality