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Regimes of bedforms created by down-slope density currents
No full textBedforms in rivers have been extensively studied for decades. Turbidite outcrops also display bedforms emplaced subaqueously by turbidity currents. Recent breakthroughs in the attainable resolution of deep underwater bathymetric/seismic mapping have revealed that bedforms in submarine environments may be as widespread and diverse as those associated with fluvial flows. Turbidity currents that emplace subaqueous bedforms run down submarine canyons, traverse and overflow leveed channels on submarine fans, or manifest themselves as sheet turbidity currents along continental margins. Submarine bedforms present features that appear to be analogous to their fluvial counterparts. Submarine bedforms have traditionally been interpreted with the use of tools, and in particular phase diagrams, that were developed solely for fluvial bedforms. The use of such tools is motivated by the fact that simultaneous observation of the bedforms as they evolve in the field and the turbidity currents that create them remains at the edge of present capabilities. We fill this gap in part with a technique that has been successfully implemented for fluvial bedforms, i.e. experimentation. We present observations of bedforms emplaced by saline and turbidity currents in laboratory flumes. The experimental flows span a wide range of densimetric Froude numbers, including both subcritical and supercritical regimes, and produced various bedform types including subcritical and supercritical-regime ripples/dunes, upstream-migrating and downstream-migrating antidunes, and cyclic steps. We have gathered a comprehensive set of fluvial and submarine field bedforms worldwide from multiple environments including submarine canyons, levees, slopes, and fans; some of which include associated flow observations. The data are summarized in a set of bedform dimensions and regime diagrams, which are applicable to saline and/or turbidity currents, and generally to any down-slope moving bottom flow. The regimes for submarine bedforms show both similarities and differences with fluvial regimes. Our diagrams and guidelines constitute a new tool for the interpretation of field-scale bedforms generated by turbidity currents
Numerical and Experimental Analysis of the Tip Leakage Flow in a Squealer Low-Pressure Turbine Blade for Different Operating Conditions
No full textThis study combines experiments and numerical simulations (3D-Reynolds-averaged Navier-Stokes (RANS)) to achieve a deep understanding of the effects induced by varying key parameters affecting tip leakage flow in a highly loaded low-pressure turbine (LPT) rotor blade. Specifically, results for flat tip configurations are compared with a squealer tip geometry for different clearance heights and mass flow ratios simulating coolant flow ejected from the tip. Experimental results map the effects of these parameters on loss generation, while detailed insights into the interaction between the tip vortex and other vortical structures within the passage are discussed through computational fluid dynamic (CFD) simulations. Available experimental data include 2D distributions of total pressure and flow angles measured with a five-hole pressure probe downstream of the cascade for different operating conditions, enabling comparison with numerical simulations. The RANS solver provides visualizations of streamlines developing close to the tip region, offering a clear interpretation of the mechanism by which cross flow motion in the tip region interacts with the pressure gradient to generate the tip leakage vortex. The study explores how these processes vary with tip gap height and different mass flow ratios, providing a comprehensive view on the development of the secondary flow system. Finally, additional simulations with moving endwall are conducted to evaluate the impact of the relative motion between the blade and casing in the current application
Later Engagements with Dickens's Life
No full textThis essay treats four recent Dickens biographies: Michael Slater's Charles Dickens: A Life Defined by Writing (2009), Claire Tomalin's Charles Dickens: A Life (2011), Robert Douglas-Fairhurst's Becoming Dickens: The Invention of a Novelist (2011), and Robert L. Patten's Charles Dickens and “Boz”: The Birth of the Industrial-Age Author (2012). The major features of each one are discussed, in order to demonstrate how they emphasize different aspects of Dickens's personality. The approaches of the biographers encompass the imaginative, the empathetic, the economic, and the lyric; taken together, they offer a richer perspective on the life of the novelist than has previously been possible
Task-Based Motion Control of an Autonomous Surface Vehicle in a Combined System with a Remotely Operated Vehicle (ASV-ROV)
No full textMarine robotics plays a crucial role in carrying out a wide range of complex underwater missions. In this context, tethered Remotely Operated Vehicles (ROVs) provide several advantages, including efficient data transmission and a reliable physical connection that ensures safety in emergency situations. However, their operational range is inherently limited by the length of the tether.
This study investigates the possibility of extending the operational range of ROVs by introducing a novel control strategy that enables cooperative operation with an Autonomous Surface Vehicle (ASV).
The proposed ASV–ROV system addresses two primary challenges: the restricted mobility of the ROV and the potential risk of cable entanglement. To mitigate these issues, a new control framework is developed to ensure smooth ROV motion while minimizing conditions that could lead to tether entanglement.
The control system allows the ASV to maintain alignment with the ROV and preserve a desired distance, while simultaneously regulating the length of cable deployed in the water.
This thesis presents the control design of the ASV motion for a cooperative navigation with the ROV. The work includes the formulation of a novel control strategy that enables the ASV to autonomously track and follow the ROV while avoiding obstacles and adjusting its trajectory to maintain safe and efficient cooperation.
The proposed control framework is validated through comprehensive software-in-the-loop simulations that represents offshore wind farm environments. The numerical results demonstrate the effectiveness and robustness of the system in improving cooperative navigation performance, reducing power consumption, and enhancing operational resilience under dynamic marine conditions.
Furthermore, the work of this thesis investigates the impact of tether management on the overall stability and energy efficiency of the ASV–ROV system. An analytical assessment of tether dynamics is conducted, supported by experimental validation in a controlled test basin, where precise measurements about underwater tether behavior were collected.
Directions for further research and system optimization are also discussed
Thomas Hobbes’s Translations of The Homeric Poems: Writing about Politics through the Iliad and the Odyssey?
No full textThis contribution aims to highlight Thomas Hobbes' instrumental use of his English translations of Homer's poems. Published in the last years of his life, these works can also be interpreted as an attempt by the Malmesbury philosopher to continue spreading his political ideas at a time when he was under censorship. By comparing the Greek text with Hobbes' translation, this contribution highlights some elements that allow us to appreciate and understand the reasons behind this Hobbes' work
Dalla Corte EDU prove di salto quantico nelle garanzie: accertamenti bancari, riserva-tezza digitale e giusto processo
No full textGeomorphological impact of short-term urbanisation on the alluvial-coastal plain of a Mediterranean military port city (La Spezia, Italy)
No full textTreg Susceptibility to Cladribine-Induced Depletion Correlates With Therapy Response in Patients With Multiple Sclerosis
No full textBackground and ObjectivesImmune reconstitution therapies for multiple sclerosis (MS) are based on selective lymphocyte reduction, followed by repopulation and rescue of immune tolerance. Among these therapies, cladribine is an adenosine analog that interferes with cell division and depletes several lymphocyte subtypes. Regulatory T cells (Tregs), physiologically devoted to immune suppression, are dysfunctional in the context of MS. In this study, we explored the effects of cladribine on Treg dynamics and phenotype.MethodsIn vivo, deep immunophenotyping was conducted on peripheral blood of patients with MS (n = 11), longitudinally collected before and after 6 and 12 months of cladribine therapy. In vitro, expanded Tregs were treated with cladribine and analyzed for their phenotypic, molecular, and metabolic profiles.ResultsIn vivo, Tregs were overall less sensitive than conventional T cells (Tconvs) to the depleting effects of cladribine. This phenomenon was particularly evident in the subset of the resting (rest) Tregs. At baseline, while activated (act) Tregs presented markers of proliferation, senescence, and survival, restTregs highly expressed the antiapoptotic protein Bcl2 and the quiescence marker Bach2. In vitro, cladribine strongly reduced Treg viability while inducing a program of senescence and dysfunction and compromising their metabolic fitness. When Treg dynamics were analyzed ex vivo in relation to neuroinflammation and response to therapy, restTregs exhibited resistance to depletion in nonresponders, in association with increasing expression of Bcl2.DiscussionThese results indicate that the efficacy of cladribine therapy may require reduction and repopulation of the Treg compartment, an event that may be hindered by restTreg resistance, which is supported by antiapoptotic signals
Dispersion monitoring services in the Mediterranean Sea: A multi-model statistical approach
No full textThe Mediterranean Sea is increasingly impacted by shipborne pollution, necessitating sophisticated oil spill monitoring systems. This study presents a detailed framework for assessing oil spill dynamics in the Mediterranean using various oceanographic models. The first part compares oil dispersion results using sea surface current data from Copernicus Marine Environment Monitoring Service (CMEMS), Naval Hydrographic and Oceanographic Service (SHOM), and French Research Institute for the Exploitation of the Sea (IFREMER). The second part evaluates particle dispersion simulations, improving upon previous results by incorporating Stokes drift and wind drag effects from the Copernicus ERA5 and the MeteOcean model, operational at DICCA Unige. The study also calculates the centroid of each oil slick to track its trajectory over time and assessing its spatial and temporal deformation. To validate the methodology, a practical case study is conducted, comparing the results with Sentinel-1 satellite images from the first days after the accident and with press reports. The results demonstrate that both Stokes drift and wind significantly influence the surface transport of oil spill, improving trajectory predictions when combined with surface currents. In addition, comparison between ocean and climate models revealed substantial variability in dispersion results, highlighting the importance of model selection in operational forecasting or the benefits of the use of a multi-model probabilistic approach