62 research outputs found

    Handling Qualities Assessment of a Pilot Cueing System for Autorotation Maneuvers

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    This paper details the design and limited flight testing of a preliminary system for visual pilot cueing during autorotation maneuvers. The cueing system is based on a fully-autonomous, multi-phase autorotation control law that has been shown to successfully achieve autonomous autorotation landing in unmanned helicopters. To transition this control law to manned systems, it is employed within a cockpit display to drive visual markers which indicate desired collective pitch and longitudinal cyclic positions throughout the entire maneuver, from autorotation entry to touchdown. A series of simulator flight experiments performed at University of Liverpool’s HELIFLIGHT-R simulator are documented, in which pilots attempt autorotation with and without the pilot cueing system in both good and degraded visual environments. Performance of the pilot cueing system is evaluated based on both subjective pilot feedback and objective measurements of landing survivability metrics, demonstrating suitable preliminary performance of the system

    Individual tree basal area increment models suitable for different stand structures in Finland

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    Forest growth models employed in Fennoscandia have been generally targeted at rotation forestry (RF) stands, relying on age as a key predictor. Uneven aged, irregular stands, such as the ones managed with continuous cover forestry, are becoming of increasingly common. New models suited for all kind of management approaches (i.e., age-independent) have been developed in Fennoscandia. Although the ongoing climate change is projected to strongly affect tree growth in boreal regions, climatic variables included in current models are usually restricted to temperature sum averages with simple links. The objectives of our research were: 1) fitting a new age independent empirical tree basal area increment model (B2023) with inclusion of additional climatic variables for the main Nordic tree species (Norway spruce, Scots pine, and birches); 2) using independent data to validate both the new model and other two age-independent published empirical models (P2013, P2021); and 3) investigating the sensitivity of growth predictions of all the empirical models to climate change. Our results showed that the new model B2023 was as accurate as P2013 when independently validated. Both models performed well in different forest structures and management alternatives (namely rotation forestry, continuous cover forestry, two-storied stands, and old-growth natural forests), although with few differences, and on average slightly better than P2021. At plot level, the new model B2023 showed slight underprediction for the overstorey pine layer in continuous cover forestry and two-storied stands. The predicted climate change scenarios increased simulated growth in all models, although P2021 showed very high values for spruce. We failed to include additional climatic variables than temperature sum in B2023, thus not improving much its accuracy under historical data, nor its sensitivity to future climate. Concluding, the individual tree models here presented can be applied to a wide range of forest structures and managements in Fennoscandia. For long-term simulation scenarios, different approaches to improve the climate sensitivity of empirical, individual tree model should be explored

    Surface Covering of Downed Logs: Drivers of a Neglected Process in Dead Wood Ecology

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    Many species use coarse woody debris (CWD) and are disadvantaged by the forestry-induced loss of this resource. A neglected process affecting CWD is the covering of the surfaces of downed logs caused by sinking into the ground (increasing soil contact, mostly covering the underside of the log), and dense overgrowth by ground vegetation. Such cover is likely to profoundly influence the quality and accessibility of CWD for wood-inhabiting organisms, but the factors affecting covering are largely unknown. In a five-year experiment we determined predictors of covering rate of fresh logs in boreal forests and clear-cuts. Logs with branches were little covered because they had low longitudinal ground contact. For branchless logs, longitudinal ground contact was most strongly related to estimated peat depth (positive relation). The strongest predictor for total cover of branchless logs was longitudinal ground contact. To evaluate the effect on cover of factors other than longitudinal ground contact, we separately analyzed data from only those log sections that were in contact with the ground. Four factors were prominent predictors of percentage cover of such log sections: estimated peat depth, canopy shade (both increasing cover), potential solar radiation calculated from slope and slope aspect, and diameter of the log (both reducing cover). Peat increased cover directly through its low resistance, which allowed logs to sink and soil contact to increase. High moisture and low temperatures in pole-ward facing slopes and under a canopy favor peat formation through lowered decomposition and enhanced growth of peat-forming mosses, which also proved to rapidly overgrow logs. We found that in some boreal forests, peat and fast-growing mosses can rapidly cover logs lying on the ground. When actively introducing CWD for conservation purposes, we recommend that such rapid covering is avoided, thereby most likely improving the CWD's longevity as habitat for many species

    La Grotta paleolitica di Roccia San Sebastiano (Mondragone, CE). Una metodologia per l’analisi dei dati in spazi simbolici

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    The Prehistory of the Mondragone area, in the province of Caserta, emerged in its importance thanks to the results of systematic surveys carried out since 1994 by the University of Naples “Federico II” and the Museum Biagio Greco together with the Archeological Superintendence of Naples and Caserta. Since 2001, the Museum has accomplished regular excavation campaigns of the very important Upper and Middle Palaeolithic deposit in the large cave opening in the site of Roccia di San Sebastiano, which represents the only evidence of Palaeolithic frequentation systematically and stratigraphically studied in the territory included between the Northern Campania coast and the Southern Latium coast. On the basis of such evidences, the authors illustrate a project aimed to produce a detailed territorial study to understand the dynamics of the frequentation and settlement of the area during Palaeolithic (Musterian, Uluzzian, Aurignazian and Gravettian) and the cultural behaviours of last Neanderthals and first Homo sapiens groups. The latest excavation campaigns allowed to unearth Uluzzian layers in two sectors of the cave and to investigate the Mousterian levels, from which a deciduous molar of a Neanderthal child comes. Moreover they permitted to consolidate the study of symbolic activities in the cave. Digital and tridimensional documentation techniques have been adopted for the description of the excavation surfaces and to understand the symbolic activities consisting in both parietal and mobiliary art evidences. The storage and elaboration of data is realized in a 3D application in order to elaborate detailed intra-site analysis in a predictive pattern of activities. This model allows the management of digital data in a single spatial system of representation, in which the digital copies of places, excavations areas and objects coincide with the relational matrices between the archaeological data and the possible events recorded in the physical layers

    CONSTRUCTING AND REPRESENTING: A NEW PROJECT FOR 3D SURVEYING OF YAZILIKAYA - HATTUŠA

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    Within the cooperation project between the University Suor Orsola Benincasa of Naples and the archaeological mission in Hattuša of the German Archaeological Institute of Istanbul, directed by Andreas Schachner, in agreement with the Turkish Ministry of Culture and Tourism, the workgroup of the University of Naples, has carried out, in September 2015, a first survey campaign of the whole rocky site of Yazılıkaya. The experimentation has been finalized at constructing a global 3D territorial and monumental model of the site, capable that is, through the application of differing scanning procedures, according to the different components (topography, rocky complex, the cultural spaces therein, complex of sculptural reliefs, inscriptions accompanying the divine representations), of virtually reproducing in detail, for safegaurd, exhibition and study purposes (in particular from an epigraphical and historic-artistic point of view) all the aspects characterizing the artefact and not completely visible to the naked eye today

    Modelling volume growth response of young Scots pine (Pinus sylvetris) stands to N, P, and K fertilization in drained peatland sites in Finland

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    Fertilizers are applied in drained peatland forests to correct nutrient imbalances, but few models have been developed for predicting the stand growth response. We used 10- to 34-year-long stem growth increment data from 51 fertilization experiments involving ash, PK, and NPK treatments (doses of P, K, and N varying between 35 and 45, 60 and 80, and 80 and 90 kg·ha–1, respectively) and controls to model the volume growth response of young Scots pine (Pinus sylvetris L.) stands to fertilization in drained peatland sites of middle and northern Finland. We used the linear mixed models method to express the stand-level growth response as a function of time (5-year periods), site type group, location, and the fertilization treatment (ash–PK combined and NPK). Different growth responses were obtained for nitrogen-rich sites with PK treatment and nitrogen-poor sites with NPK treatment. The PK fertilization in nitrogen-rich sites resulted in the largest volume growth response and longest temporal effect (1.0–2.0 m3·ha–1·a–1 higher mean growth for at least 35 years), with quicker and stronger effects in more southern conditions where average temperature sums were greater than 1000 degree-days (°C). NPK fertilization in nitrogen-poor sites gave a modest response (0.4–0.8 m3·ha–1·a–1 in 35 years). </jats:p
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