Alternatives for the development of new industrial crops for Patagonia

The search for potential arid-adapted crops has yielded several species that produce industrial raw materials and can be cultivated in warm arid lands. However, there are few species adapted to cold arid environments like Patagonia. The objectives of this paper are to propose criteria for the search and development of new industrial crops for Patagonia, to analyze those species that have been suggested as potential crops, and to propose other candidates based on these criteria. We discuss the potential of the few species cited as potential crops for Patagonia: Colliguaya integerrima (Euphorbiaceae) and Lesquerella mendocina (Brassicaceae) as seed-oil sources; Grindelia chiloensis (Asteraceae), Colliguaya integerrima, Larrea sp. (Zygophyllaceae), and Mulinum spinosum (Umbelliferae) as politerpene sources, and Prosopis and Cercicium sp. as gum sources. We include a description of prospective families for oils, gums and terpenes

Flight-Test Evaluation of Landing Gear Noise Reduction Technologies

Results from the third Acoustics Research Measurements flight test, conducted under the NASA Flight Demonstrations and Capabilities project, are presented and discussed. The test evaluated landing gear and gear cavity noise mitigation technologies installed on a NASA Gulfstream G-III. Aircraft configurations with and without main landing gear treatments were flown at several flap deflections to determine the acoustic performance of the technologies for aircraft equipped with conventional Fowler flaps. With the aircraft flying an approach path and engines at ground-idle, extensive acoustic measurements were acquired with a phased microphone array system. Computed beamform maps were used to examine the effectiveness of the tested technologies in reducing the strength of the noise sources generated by the main landing gear. Various integration regions were devised to extract the farfield noise spectra associated with the treated and untreated landing gear configurations. Analyses of the gathered acoustic data demonstrate that significant noise reduction was achieved. How- ever, the full noise reduction potential of the technologies could not be determined because of contamination from flap inboard edge noise and other secondary sources

Measured and Simulated Acoustic Signature of a Full-Scale Aircraft with Airframe Noise Reduction Technology Installed

Microphone phased-array and pole-mounted microphone data gathered during the NASA Acoustics Research Measurements flight tests were used to benchmark results from companion full-scale aeroacoustics simulations. Conducted with the lattice Boltzmann solver PowerFLOW, the simulations predicted the acoustic behavior of various tested aircraft configurations. Emphasis was placed on those flown during the third flight test - a Fowler flap-equipped Gulfstream G-III with and without noise abatement technology on the main landing gear. Direct comparisons between experimental and synthetic microphone phasedarray data were achieved by applying the same processing and deconvolution technique to both sets of data. To extend the validation of the computations to the metric used for noise certification, the Effective Perceived Noise Level, a high-fidelity digital model of the nose landing gear, which was excluded from earlier computations, was developed and integrated into the G-III aircraft geometry. The acoustic study presented here demonstrates that the simulated beamform maps and corresponding integrated farfield spectra accurately predict the locations and strengths of the prominent airframe noise sources present on the G-III aircraft

Assessment of Airframe Noise Reduction Technologies Based on EPNL from Flight Tests

The acoustic performance of various airframe noise reduction technologies Adaptive Compliant Trailing Edge flap, main landing gear fairings, and gear cavity treatments was determined, individually and in combination, using the Effective Perceived Noise Level metric. These noise measurements and calculations closely follow the Federal Aviation Administration aircraft noise certification standards, specifically for the approach noise measurement point. The flyover data correspond to pole-mounted, single-microphone measurements obtained during a series of flight tests, conducted under the NASA Flight Demonstrations and Capabilities project, that evaluated flap and landing gear noise reduction technologies. To minimize contributions from the propulsion system, the aircraft was flown along the approach path with engine thrust set at ground idle. Although contamination from engine, background, and secondary airframe noise sources partially masked the true performance of the tested technologies, the resulting acoustic data clearly showed substantial noise reductions relative to baseline levels. The acoustic benefits measured by the single microphones are consistent with previously reported trends in acoustic levels obtained from phased microphone array data

Acoustic Measurements of a Large Civil Transport Main Landing Gear Model

Microphone phased array acoustic measurements of a 26 percent-scale, Boeing 777-200 main landing gear model with and without noise reduction fairings installed were obtained in the anechoic configuration of the Virginia Tech Stability Tunnel. Data were acquired at Mach numbers of 0.12, 0.15, and 0.17 with the latter speed used as the nominal test condition. The fully and partially dressed gear with the truck angle set at 13 degrees toe-up landing configuration were the two most extensively tested configurations, serving as the baselines for comparison purposes. Acoustic measurements were also acquired for the same two baseline configurations with the truck angle set at 0 degrees. In addition, a previously tested noise reducing, toboggan-shaped fairing was re-evaluated extensively to address some of the lingering questions regarding the extent of acoustic benefit achievable with this device. The integrated spectra generated from the acoustic source maps reconfirm, in general terms, the previously reported noise reduction performance of the toboggan fairing as installed on an isolated gear. With the recent improvements to the Virginia Tech tunnel acoustic quality and microphone array capabilities, the present measurements provide an additional, higher quality database to the acoustic information available for this gear model

Comparison of Measured and Simulated Acoustic Signatures for a Full-Scale Aircraft with and Without Airframe Noise Abatement

No abstract availabl

Aeroacoustic Evaluation of Flap and Landing Gear Noise Reduction Concepts

Aeroacoustic measurements for a semi-span, 18% scale, high-fidelity Gulfstream aircraft model are presented. The model was used as a test bed to conduct detailed studies of flap and main landing gear noise sources and to determine the effectiveness of numerous noise mitigation concepts. Using a traversing microphone array in the flyover direction, an extensive set of acoustic data was obtained in the NASA Langley Research Center 14- by 22-Foot Subsonic Tunnel with the facility in the acoustically treated open-wall (jet) mode. Most of the information was acquired with the model in a landing configuration with the flap deflected 39 deg and the main landing gear alternately installed and removed. Data were obtained at Mach numbers of 0.16, 0.20, and 0.24 over directivity angles between 56 deg and 116 deg, with 90 deg representing the overhead direction. Measured acoustic spectra showed that several of the tested flap noise reduction concepts decrease the sound pressure levels by 2 - 4 dB over the entire frequency range at all directivity angles. Slightly lower levels of noise reduction from the main landing gear were obtained through the simultaneous application of various gear devices. Measured aerodynamic forces indicated that the tested gear/flap noise abatement technologies have a negligible impact on the aerodynamic performance of the aircraft model

Population structure and seed yield of a wild stand of Physaria mendocina (Brassicaceae) Implications for its development as an oilseed crop

Physaria mendocina, es una hierba perenne nativa del Monte en Argentina, de la que existen pocas poblaciones conspicuas y que ha sido propuesta como un nuevo cultivo oleaginoso para zonas áridas. Evaluamos una población en el Parque Nacional Lihué Calel (La Pampa, Argentina) con los objetivos de: 1) caracterizar la distribución espacial, la densidad y la estructura de tamaños, y 2) determinar cómo se relacionan estos factores con la producción de semilla. Se esperaba una distribución agregada con parches de alta y baja densidad. Se evaluó la población durante tres años y se estudiaron las relaciones entre las variables demográficas y las productivas. La población de P. mendocina mostró un patrón de distribución agregado. En parches de menor densidad, aumentó la proporción de individuos de mayor tamaño, en contraposición a los parches más densos, donde prevalecieron individuos más pequeños. Las plantas de menor tamaño tuvieron menor acumulación de biomasa y producción de semilla, jerarquizando la asignación de biomasa hacia estructuras subterráneas. La biomasa individual es el componente que mejor explicó la variación del rendimiento por planta entre individuos de tamaño diferente. El entendimiento de los mecanismos funcionales determinantes de la producción de semillas es un requisito para la conservación y la domesticación de esta especie.Wild stands of the perennial forb Physaria mendocina (syn Lesquerella mendocina, Brassicaceae), are uncommon, small and inconspicuous. This species, native to the Monte desert, is being evaluated as a new oil-seed crop for arid lands. We evaluated a wild population in the Lihué Calel National Park (La Pampa, Argentina) for three years: 2000, 2001, and 2002. The aims of our study were: 1) to characterize the spatial distribution, density and size structure of this population, and 2) to analyze the relationship between population structure and individual plant seed-production. The relationship between population structure and productivity was evaluated using path analysis. We found an aggregated spatial distribution pattern, with patches of high and low density. The proportion of larger size individuals increased in low density patches, respect to those in with high density in which prevailed smaller individuals. Smaller plants had less biomass accumulation and seed production, and had a greater below ground allocation, in relation to larger plants. Individual total biomass was the main determinant of the observed variation in seed-yield in relations to plant size, while harvest index was very stable across the range of plant diameter. The understanding of functional mechanics of seed production should aid in the conservation of wild stands, and in the domestication of this perennial species

Comparison of Computational and Experimental Microphone Array Results for an 18% Scale Aircraft Model

An 18% scale semispan model is used as a platform for examining the efficacy of microphone array processing using synthetic data from numerical simulations. Two hybrid Reynolds-Averaged-Navier-Stokes/Large-Eddy-Simulation (RANS/LES) codes coupled with Ffowcs WilliamsHawkings solvers are used to calculate 97 microphone signals at the locations of an array employed in the NASA Langley Research Center 14 22 tunnel. Conventional, DAMAS, and CLEAN-SC array processing is applied in an identical fashion to the experimental and computational results for three different configurations involving deploying and retracting the main landing gear and a part-span flap. Despite the short time records of the numerical signals, the beamform maps are able to isolate the noise sources, and the appearance of the DAMAS synthetic array maps is generally better than those from the experimental data. The experimental CLEAN-SC maps are similar in quality to those from the simulations indicating that CLEAN-SC may have less sensitivity to background noise. The spectrum obtained from DAMAS processing of synthetic array data is nearly identical to the spectrum of the center microphone of the array, indicating that for this problem array processing of synthetic data does not improve spectral comparisons with experiment. However, the beamform maps do provide an additional means of comparison that can reveal differences that cannot be ascertained from spectra alone