323,206 research outputs found
Uncertainty of drone-derived dems and significance of detected morphodynamics in artificially scraped dunes
No full textThis work capitalises on the morphodynamic study of a scraped artificial dune built on the sandy beach of Porto Garibaldi (Comacchio, Italy) as a barrier to protect the touristic facilities from sea storms during the winter season and contributes to understanding of the role of elevation data uncertainty and uniform thresholds for change detection (TCDs) on the interpretation of volume change estimations. This application relies on products derived from unmanned aerial vehicle (UAV) surveys and on the evaluation of the uncertainty associated with volume change estimations to interpret the case study morphodynamics under non-extreme sea and wind conditions. The analysis was performed by comparing UAV-derived digital elevation models (DEMs)-root mean squared error (RMSE) vs. global navigation satellite system (GNSS) < 0.05 m-and orthophotos, considering the significance of the identified changes by applying a set of TCDs. In this case, a threshold of similar to 0.15 m was able to detect most of the morphological variations. The set of TCD <= 0.15 m was considered to discuss the significance of minor changes and the uncertainty of volume change calculations. During the analysed period (21 December 2016-20 January 2017), water levels and waves affected the front of the artificial dune by eroding the berm area; winds remodelled the entire dune, moving the loose sand around the dune and further inland; sediment volumes mobilised by sea and wind forcing were comparable. This work suggests that UAV-derived coastal morphological variations should be interpreted by integrating: (i) a set of uniform thresholds to detect significant changes; (ii) the uncertainty generated by the propagation of the original uncertainty of the elevation products; (iii) the characteristics of the morphodynamic drivers evaluated by adopting uncertainty-aware approaches. Thus, the contribution of subtle morphological changes-magnitudes comparable with the instrumental accuracy and/or the assessed propagated uncertainty-can be properly accounted for
Sedimentation at River Mouths bounded by Coastal Structures: A Case Study along the Emilia-Romagna Coastline, Italy
No full textBeach retreat in the Emilia-Romagna coast, facing the north Adriatic Sea, is well-known since decades and several factors are behind this phenomenon: a scarcity of natural sediment supply by rivers, natural and anthropogenic subsidence, and a strong urbanization of the coastal zone. Several bedload measurement campaigns in one representative river of the Ravenna province (Savio River) have been carried out since 2017. At the same time, seasonal surveys of bathymetry were undertaken at the river outlet to correlate changes in sedimentation with river input. The river mouth is constrained by artificial embankments that possibly funnel out sediment offshore during river floods. However, monitoring of bedload transport correlated with bathymetric changes between July 2017 and November 2018 still found a positive budget of almost 5000 cubic meters. Local authorities in Ravenna are planning to dredge 20000 cubic metres from the river mouth to supply small nourishments outside the studied coastal cell. According to the measurements of bathy-metric changes, the Savio mouth will need almost six years to recover, assuming the occurrence of a particularly efficient rate of sediment transport, like the one observed in the monitored period. Notably, the analysed period included a very large river flood that could overshadow the modal sediment transport operated by the river. Furthermore, with deepening of the mouth, the two villages adjacent to the outlet are likely to become more exposed to sea flooding, due to the propagation of surges inside the river mouth. The paper concludes that dredging activities should be reconsidered in view of the precarious equilibrium of the system
The Role of Detailed Geomorphic Variability in the Vulnerability Assessment of Potential Oil Spill Events on Mixed Sand and Gravel Beaches: The Cases of Two Adriatic Sites
No full textThe role of short- to medium-term geomorphic variation is analyzed in two Italian mixed sand and gravel beaches to better understand how it could affect vulnerability assessments of oil spill events. The study sites, Portonovo and Sirolo, are in one of the most congested areas for oil transportation in the Adriatic Sea (Ancona port). A “snapshot” situation populated with field data collected in April 2015 is compared to a “changing” situation built with previous field datasets (topographic surveys and surface sediment samplings) available for the two beaches. According to the ESI guidelines established by the National Oceanic and Atmospheric Administration [NOAA], 2002, both Portonovo and Sirolo can be ranked as ESI 5 or 6A in most of the cases. Sediment size resulted in the most decisive factor for the ESI assessment. As consequence of the bimodal direction of storms, the high geomorphic variability on the two sites ismainly related to storm berms which lead to rapid burial processes on both beaches. In oil spill circumstances, burial is considered the most alarming factor, especially on microtidal mixed beaches that develop storm berms so high and close to the shoreline. A quantification of the maximum potential depth reachable by the oil in the beach body is therefore needed for the most dynamic beaches; this could be achieved with repeated field measurements to be performed in the period between two consecutive ESI updates (5–7 years) and the addition of an appendix in the ESI maps dealing with the geomorphic characteristics of the beach. The significance of a changing ESI rank is that the authorities in charge of responding to the oil spill could be improperly preparedfor the conditions that exist at a spill site if the geomorphology has changed from when it was first given an ESI rank
Strengthened Techniques for the Renewed Industrial Interest in Plant Data Reconciliation Benefits
No full textThe renewed interest in the process data reconciliation by both the academic world and the process industries is mainly due to the introduction of new process control technologies such as the model predictive control, the real time dynamic optimization and the enterprise resource planning, all requiring a continuous (on-line) maintenance and optimization. The paper discusses the existing techniques for solving a data reconciliation problem, proposes some emerging methodologies, and introduces the open issue of the real-time nonlinear reconciliation based on detailed models
Skeletal P/Ca tracks upwelling in Gulf of Panama coral: Evidence for a new seawater phosphate proxy
No full textThe supply of limiting nutrients to the low latitude ocean is controlled by physical processes linked to climate variations, but methods for reconstructing past nutrient concentrations in the surface ocean are few and indirect. Here, we present laser ablation mass spectrometry results that reveal annual cycles of P/Ca in a 4-year record from the scleractinian coral Pavona gigantea (mean P/Ca = 118 mmol mol?1). The P/Ca cycles track variations in past seawater phosphate concentration synchronously with skeletal Sr/Ca-derived temperature variations associated with seasonal upwelling in the Gulf of Panama´. Skeletal P/Ca varies seasonally by 2–3 fold, reflecting the timing and magnitude of dissolved phosphate variations. Solution cleaning experiments on drilled coral powders show that over 60% of skeletal P occurs in intracrystalline organic phases. Coral skeleton P/Ca holds promise as a proxy record of nutrient availability on time scales of decades to millennia
Adaptive Data Reconciliation Coupling C++ and PRO/II and On-line Application by the Field
No full textThe paper discusses the possibility of coupling object-oriented programming languages such as Visual C++ and the commercial simulators such as PRO/II, UniSim, and AspenHysys to get a generalized framework for robust and reliable data reconciliation of sulfur recovery units by taking to a series of benefits from their interaction: (i) simulation software provides a high-level and field-proven degree of detail in simulating processes; (ii) they usually allow inferring measures even when the instrumentation presents serious lacks by the field; and (iii) the programming languages allow using specific numerical libraries to solve large-scale, nonlinear, constrained optimization problems by making them feasible even for the on-line industrial application. The proposed approach was validated on a large-scale Sulfur Recovery Unit (technology by Technip-KTI SpA) operating in an oil refinery placed in Italy
Two-way bending experimental response of URM walls subjected to combined horizontal and vertical seismic excitation
No full textThis paper presents the results of incremental dynamic tests on full-scale unreinforced masonry (URM) walls constructed with an intentionally weakened mortar under two-way bending excitation in the out-of-plane (OOP) direction. A specimen was also subjected to simultaneous vertical and horizontal excitation. Walls were also tested in boundary conditions that have not been previously reported in the literature. Emphasis was placed on the development and interpretation of a characterisation test to estimate the torsional shear strength of bed-joints, a parameter of prime importance in the OOP two-way bending behaviour of URM walls. Analytical formulation to estimate the initial stiffness of walls based on the theory of plates is then proposed and validated. Being the first experimental campaign to address the dynamic OOP two-way bending response of full-scale URM wall panels provided the opportunity to propose simple yet mechanically rational methodologies with which both the peak force resistance as well as the displacement at which such resistance is attained can be easily estimated
FusaHelp. A web site program for the morphological identification of Fusarium species
No full textFusarium is one of the most important phytopathogenic fungi of agricultural and human concern. More than 300 species have been described, many of which are pathogenic to important crops, flowers, forest trees, animals, and humans. Species belonging to this genus have been detected in all environments: grassland, desert, littoral, agricultural, alpine zones, aquatic, man-made, and hospitals. Despite the importance of molecular techniques for the identification of a fungal species, morphological criteria still have an important role, including for Fusarium species, for which morphological identification of species requires adequate training and experience. In this paper, we present FusaHelp, a computer-based, user-friendly tool for the morphological identification of common Fusarium species, based on the wide experience of the authors who have devoted most of their scientific careers to the identification and characterization of these species. The web-location of FusaHelp (https://www.fusahelp.com) will greatly facilitate morphological identification and is intended to provide support for all those people who work with this important genus and need a quick clue on the identification, even incomplete, of the Fusarium species that they are working with. © 2023, The Author(s)
Experimental response of URM single leaf and cavity walls in out-of-plane two-way bending generated by seismic excitation
No full textOut-of-plane (OOP) mechanisms are one of the major causes of structural collapse in unreinforced masonry (URM) buildings as observed in recent as well as past seismic events. Among such failures, two-way bending mechanisms involving at least one restrained vertical edge constitute a very distinct majority. Nevertheless, very little research pertaining to such mechanisms can be found currently in literature. The paper takes a step forward in this topic through the execution and interpretation of dynamic tests on four full-scale single leaf and one full-scale cavity URM walls. Each tested full-scale specimen consisting of a OOP panel and two return walls, varying in terms of commonly encountered boundary conditions, applied overburden or the presence/absence of an opening. The specimens were subjected to sequences of incremental input motion till collapse and these results are presented in terms of deformed shapes, failure mechanisms and force-displacement hysteretic curves. State of the art analytical techniques based on the method of virtual work are applied to evaluate their reliability as simplified tools for assessing the behaviour of such wall subjected to OOP two-way bending excitation. The testing campaign resulted in all specimens exhibiting a rather brittle response, despite sustaining accelerations of 1 g without any damage
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