Navigation and guidance requirements for commercial VTOL operations

The NASA Langley Research Center (LaRC) has undertaken a research program to develop the navigation, guidance, control, and flight management technology base needed by Government and industry in establishing systems design concepts and operating procedures for VTOL short-haul transportation systems in the 1980s time period. The VALT (VTOL Automatic Landing Technology) Program encompasses the investigation of operating systems and piloting techniques associated with VTOL operations under all-weather conditions from downtown vertiports; the definition of terminal air traffic and airspace requirements; and the development of avionics including navigation, guidance, controls, and displays for automated takeoff, cruise, and landing operations. The program includes requirements analyses, design studies, systems development, ground simulation, and flight validation efforts

Display/control requirements for VTOL aircraft

Quantative metrics were determined for system control performance, workload for control, monitoring performance, and workload for monitoring. Pilot tasks were allocated for navigation and guidance of automated commercial V/STOL aircraft in all weather conditions using an optimal control model of the human operator to determine display elements and design

Preliminary investigation of cooling-air ejector performance at pressure ratios from 1 to 10

Preliminary investigation was made of conical cooling air ejector at primary pressure ratios from 1 to 10. The cooling-air flow was maintained at zero and the resulting pressure variation in the shroud indicated pumping ability. The cooling-air flow was maintained at zero and the resulting pressure variation in the shroud indicated pumping ability. The gross thrust of the ejector and nozzle were compared. Several ratios of the spacing between the nozzle and shroud exit to the nozzle exit diameter were investigated for several shroud to nozzle exit diameter ratios. Maximum gross thrust loss occurred under conditions of zero cooling-air flow and was as much as 35 percent below nozzle jet thrust. For minimum thrust loss, ejector should be designed with as low diameter and spacing ratio as possible

Temperature-dependent expression of a collagen splicing defect in the fibroblasts of a patient with Ehlers-Danlos syndrome type VII.

Abstract In this article we report the characterization of the molecular lesion in a patient with Ehlers-Danlos syndrome Type VII and provide evidence that a de novo substitution of the last nucleotide of exon 6 in one allele of the pro-alpha 2(I) collagen gene produces normally spliced mRNA and transcripts from which exon 6 sequences have been outspliced as well. Unexpectedly, the expression of the alternative splicing was found to be temperature-dependent, for missplicing in cellula is effectively abolished at 31 degrees C and gradually increases to 100% at 39 degrees C. In contrast, in a similar patient harboring a substitution in the obligatory GT dinucleotide of the 5' splice site of intron 6, complete outsplicing of exon 6 sequences was found at all temperatures

Preliminary Assessment of Nonpoint Source Related Ambient Toxicity in and around Lower Galveston Bay

In 1991 aquaculture researchers at the old SeaArama facility in Galveston believed that mortality they were observing in their larval shrimp cultures was a result of toxicity of ambient water in the Gulf of Mexico. The researchers utilized near-shore Gulf of Mexico water for rearing larval shrimp. They hypothesized that 2-butoxyethanol was the toxic agent, originating from Galveston Bay waters flowing into the Gulf following heavy rainfall. However, data were not available to support this hypothesis. The US Environmental Protection Agency (EPA) and the Texas Natural Resource Conservation Commission (TNRCC) in a combined effort decided to conduct a water quality study to investigate these concerns. The purposes of the study were to assess the potential for ambient toxicity in lower Galveston Bay and the Gulf of Mexico following rainfall events, and to determine the need for additional studies for a more complete assessment. A total of five stations were sampled during three sampling events: (I) November 1992, (II) June 1993 and (III) February 1994. Sampling stations included Galveston Bay near Redfish Reef, Galveston Channel, and near-shore Gulf of Mexico off Galveston Island. Two additional industrialized areas were also sampled, Texas City Ship Channel and Chocolate Bay. An attempt was made to sample following significant rainfall in the Galveston Bay watershed to assess the potential impact of nonpoint source pollution on bay water quality. Ambient surface water samples were collected for chemical analysis of conventional parameters, EPA priority pollutants (heavy metals, VOCs, semi-volatiles, pesticides and PCBS), and chronic toxicity testing with mysids and inland silversides. Overall, chemical water quality was good for all sites. The chemical analysis yielded no violations of state water quality standards. Bis(2-ethylhexyl)phthalate at the Gulf of Mexico station exceeded the EPA criterion for protection of human health in February 1994, although the significance is doubtful as this is a common lab contaminant. In November 1992 dissolved nickel approached the state's chronic water quality standard at Chocolate Bay. Chronic toxicity data for mysids and inland silversides, although limited, did not indicate significant chronic effects to either species. Because this was a screening study data should be considered preliminary. Chemical and toxicity data indicate that aquatic life uses in the open bay areas sampled are not impacted by toxic substances originating from non-point sources. The need for future open bay type nonpoint source surface water studies is considered low. Studies to assess localized and/or episodic effects of urban storm water discharges and industrial and agricultural runoff (e.g., western near-shore areas of Galveston Bay; Chocolate Bayou upstream of the area sampled in this study) would be of greater value

Using computer vision to identify limpets from their shells: a case study using four species from the Baja California peninsula

The shell morphology of limpets can be cryptic and highly variable, within and between species. Therefore, the visual identification of species can be troublesome even for experts. Here, we demonstrate the capability of computer vision models as a new method to assist with identifications. We investigate the ability of computers to distinguish between four species and two genera of limpets from the Baja California peninsula (Mexico) from digital images of shells from both dorsal and ventral orientations. Overall, the models performed marginally better (97.9%) than experts (97.5%) when predicting the same set of images and did so 240x faster. Moreover, we utilised a heatmap system to both verify that models are focussing on the specimens and to view which features on the specimens the models used to distinguish between species and genera. We then enlisted the expertise of limpet ecologists specialised in identification of species from the Baja peninsula to comment on whether the heatmaps are indeed focusing on specific morphological features per species/genus. They confirm that in their opinion, the majority of the heatmaps appear to be highlighting areas and features of morphological importance for distinguishing between groups. Our findings reveal that the cutting-edge technology of computer vision holds tremendous potential in enhancing species identification techniques used by taxonomists and ecologists. Not only does it provide a complementary approach to traditional methods, but it also opens new avenues for exploring the biology and ecology of limpets in greater detail

Experimental warming differentially affects vegetative and reproductive phenology of tundra plants

Rapid climate warming is altering Arctic and alpine tundra ecosystem structure and function, including shifts in plant phenology. While the advancement of green up and flowering are well-documented, it remains unclear whether all phenophases, particularly those later in the season, will shift in unison or respond divergently to warming. Here, we present the largest synthesis to our knowledge of experimental warming effects on tundra plant phenology from the International Tundra Experiment. We examine the effect of warming on a suite of season-wide plant phenophases. Results challenge the expectation that all phenophases will advance in unison to warming. Instead, we find that experimental warming caused: (1) larger phenological shifts in reproductive versus vegetative phenophases and (2) advanced reproductive phenophases and green up but delayed leaf senescence which translated to a lengthening of the growing season by approximately 3%. Patterns were consistent across sites, plant species and over time. The advancement of reproductive seasons and lengthening of growing seasons may have significant consequences for trophic interactions and ecosystem function across the tundra