Skin friction measuring device for aircraft

A skin friction measuring device for measuring the resistance of an aerodynamic surface to an airstream is described. It was adapted to be mounted on an aircraft and is characterized by a friction plate adapted to be disposed in a flush relationship with the external surface of the aircraft and be displaced in response to skin friction drag. As an airstream is caused to flow over the surface, a potentiometer connected to the plate for providing an electrical output indicates the magnitude of the drag

F-8 supercritical wing flight pressure, Boundary layer, and wake measurements and comparisons with wind tunnel data

Data for speeds from Mach 0.50 to Mach 0.99 are presented for configurations with and without fuselage area-rule additions, with and without leading-edge vortex generators, and with and without boundary-layer trips on the wing. The wing pressure coefficients are tabulated. Comparisons between the airplane and model data show that higher second velocity peaks occurred on the airplane wing than on the model wing. The differences were attributed to wind tunnel wall interference effects that caused too much rear camber to be designed into the wing. Optimum flow conditions on the outboard wing section occurred at Mach 0.98 at an angle of attack near 4 deg. The measured differences in section drag with and without boundary-layer trips on the wing suggested that a region of laminar flow existed on the outboard wing without trips

Identifying environmental drivers of fungal non-pollen palynomorphs in the montane forest of the eastern Andean flank, Ecuador

Samples taken from sedimentary archives indicate that fungal non-pollen palynomorphs (NPPs) can be used to provide information on forest cover, fire regime, and depositional environment in the eastern Andean flank montane forest of Ecuador. Within the 52 samples examined, 54 fungal NPP morphotypes are reported, of which 25 were found to be previously undescribed. Examination of fungal NPPs over a gradient of forest cover (2–64%) revealed three distinct assemblages: (1) low (Neurospora, IBB-16, HdV-201, OU-102, and OU-110 indicative of an open degraded landscape; (2) medium (8–32%) forest cover Cercophora-type 1, Xylariaceae, Rosellinia-type, Kretzschmaria deusta, Amphirosellinia, Sporormiella, and Glomus suggestive of a forested landscape disturbed by herbivores and soil erosion; and (3) high (32–63%) forest cover Anthostomella fuegiana, OU-5, OU-101, OU-108, and OU-120. Environmental variables for forest cover (forest pollen), available moisture (aquatic remains), regional fire regime (microcharcoal), and sediment composition (organic carbon) were found to explain ~40% of the variance in the fungal NPP data set. Fire was found to be the primary control on fungal NPP assemblage composition, with available moisture and sediment composition the next most important factors

Comparisons of wing pressure distribution from flight tests of flush and external orifices for Mach numbers from 0.50 to 0.97

Wing pressure distributions obtained in flight with flush orifice and external tubing orifice installations for Mach numbers from 0.50 to 0.97 are compared. The procedure used to install the external tubing orifice is discussed. The results indicate that external tubing orifice installations can give useful results

Challenges and directions toward a general theory of ecological recovery dynamics: A metacommunity perspective

Global change degrades ecosystems worldwide. Scientific research has advanced our knowledge of the impacts of global change on ecosystems. Comparatively, however, it remains unclear how ecosystems recover after disturbances. In this perspective, I contend that ecological restoration should advance toward a general, dynamic theory that describes the recovery rates and trajectories of ecosystems along restoration. This approach should address three fundamental challenges corresponding to three components of ecological systems: complexity (how do we quantify ecological restoration?), space (what are the spatial scales of restoration?), and global change (how does global change determine restoration's reference states?). A generic model and experiment based on metacommunities is used to illustrate how these challenges can be addressed. Given the extent of ecosystem degradation and the international consensus to restore ecosystems, revealing the patterns and mechanisms underlying recovery is a fundamental and timely issue toward a general theory of ecological restorationD.M. was funded by the French ANR through LabEx TULIP ( ANR-10-LABX-41 ; ANR-11-IDEX-002-02 ) and by the European Research Council (FRAGCLIM Consolidator Grant no. 726176 ). I also thank Dominique Gravel and two anonymous reviewers for their comments, which have greatly improved this manuscript

Variation in diversity–function relationships can be explained by species interactions

Research Highlight: Wu, D., Xu, C., Wang, S., Zhang, L., & Kortsch, S. (2022). Why are biodiversity–ecosystem functioning relationships so elusive? Trophic interactions may amplify ecosystem function variability. Journal of Animal Ecology, https://doi.org/10.1111/1365-2656.13808. There is consensus that average trends of ecosystem functions increase with species diversity. However, large variations in ecosystem function (VEF) in systems with similar diversity levels are commonly observed, yet not understood. In this study, Wu et al. (2022) integrate empirical aquatic food webs with a multitrophic model to show that VEF generally shows a hump-shaped pattern along the species richness gradient. This pattern is related to changes in taxa composition across trophic levels—the proportion of consumer species relative to basal species—along the gradient of species richness. Thus, VEF dependence on species diversity is driven by both bottom-up and top-down control that regulate taxa composition and taxa dominance. These results are corroborated with an independent food web dataset from the Gulf of Riga. An important implication of this study is that biodiversity loss may not only reduce the mean levels of ecosystem functioning, but also increase unpredictability of functions by generating greater function variability. © 2022 The Author. Journal of Animal Ecology © 2022 British Ecological Society.I would like to acknowledge the financial support provided by María de Maeztu excellence accreditation 2018‐2022 (MDM‐2017‐0714), funded by MCIN/AEI/ http://doi.org/10.13039/501100011033 /; the Basque Government through the BERC 2022‐2025 program; the Spanish Ministry of Science & Innovation and by the European Social Fund through the Ramón y Cajal Program (RYC2020‐028780‐I) and the ERC (ERC Consolidator Grant RECODYN 101043548)

Flight experience with a pivoting traversing boundary-layer probe

A pivoting traversing boundary layer probe was evaluated in flight on an F-104 airplane. The evaluation was performed at free stream Mach numbers from 0.8 to 2.0. The unit is described, and operating problems and their solutions are discussed. Conventional boundary layer profiles containing variations in flow angle within the viscous layer are shown for free stream Mach numbers of 0.8, 1.6, and 2.0. Although the unit was not optimized for size and weight, it successfully measured simultaneously flow angularity, probe height, and pitot pressure through the boundary layer

Trace Fossils, Process, and Documents

This paper examines fossils as documents. Fossils are informative in the documentary world because they represent the skeletal structures of once-living organisms—therefore, they are the documentary remnants of something that, previously, was a fully-complete organism or documentary entity. The production of trace fossils can be a useful conceptual model to help us better understand the processual quality of documentary entities. Trace fossils, given how they are produced through the activities of organisms, are fundamentally altered or always-partial representations of past organic entities and events. They illustrate how we can potentially conceive of all documents as partial and part of an unfolding process of articulation—documents are never complete and, thus, we should not treat their content as if it were. We should not reify documents as primarily representations of information or knowledge, as they actually primarily constituted by the things we lose in this process of creation, and that that our individual processes are struggling to recreate them to best of our abilities