84 research outputs found

    Unusual becoming Usual: recent persistent-rainstorm events and their implications for debris flow risk management in the northern Apennines of Italy

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    The alluvial events of Parma (13 October 2014) and Piacenza (13-14 September 2015) in the northern Apennines of Italy have had significant effects in terms of flooding and morphological changes along the main and secondary rivers of the affected areas. The paper presents a summary of the characteristics of the rainstorm events, as well as of the triggered debris flows and their consequences on infrastructures. In the perspective of an extremization of rainfall regimes as a consequence of ongoing climate changes, these phenomena might become quite usual in the future and should be further studied in order to define regional-specific triggering thresholds, analyse precursors from weather radar datasets and assess susceptibility on a regional scale basis

    Displacements of an Active Moderately Rapid Landslide\u2014A Dataset Retrieved by Continuous GNSS Arrays

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    This paper describes a dataset of continuous GNSS positioning solutions referring to slope movements in the Ca’ Lita landslide (Northern Apennines, Italy). The dataset covers the period from 24 March 2016 to 17 July 2019 and includes time-series of the daily position of three GNSS rovers located in different parts of the landslide: head zone, upper track zone, and lower track zone. Two different types of continuous GNSS arrays have been used: one is based on high-end Leica geodetic receivers, and the other is based on low-cost effective Emlid receivers. Displacements captured in the dataset are up to more than a hundred meters and are characterized by prolonged phases of slow movement and moderately rapid acceleration phases. The data presented in this contribution were used to underline slope processes and validate displacements retrieved by the application of digital image correlation to a stack of a satellite images

    Rapid Assessment of Landslide Dynamics by UAV-RTK Repeated Surveys Using Ground Targets: The Ca’ Lita Landslide (Northern Apennines, Italy)

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    The combined use of Uncrewed Aerial Vehicles (UAVs) with an integrated Real Time Kinematic (RTK) Global Navigation Satellite System (GNSS) module and an external GNSS base station allows photogrammetric surveys with centimeter accuracy to be obtained without the use of ground control points. This greatly reduces acquisition and processing time, making it possible to perform rapid monitoring of landslides by installing permanent and clearly recognizable optical targets on the ground. In this contribution, we show the results obtained in the Ca’ Lita landslide (Northern Apennines, Italy) by performing multi-temporal RTK-aided UAV surveys. The landslide is a large-scale roto-translational rockslide evolving downslope into an earthslide–earthflow. The test area extends 60 × 103 m2 in the upper track zone, which has recently experienced two major reactivations in May 2022 and March 2023. A catastrophic event took place in May 2023, but it goes beyond the purpose of the present study. A total of eight UAV surveys were carried out from October 2020 to March 2023. A total of eight targets were installed transversally to the movement direction. The results, in the active portion of the landslide, show that between October 2020 and March 2023, the planimetric displacement of targets ranged from 0.09 m (in the lateral zone) to 71.61 m (in the central zone). The vertical displacement values ranged from −2.05 to 5.94 m, respectively. The estimated positioning errors are 0.01 (planimetric) and 0.03 m (vertical). The validation, performed by using data from a permanent GNSS receiver, shows maximum differences of 0.18 m (planimetric) and 0.21 m (vertical). These results, together with the rapidity of image acquisition and data processing, highlight the advantages of using this rapid method to follow the evolution of relatively rapid landslides such as the Ca’ Lita landslide

    MAC Layer QoS Mechanisms for a Geostationary Satellite Network

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    An efficient resource management is crucial in supporting multimedia traffic in satellite networks. To this, Dynamic Bandwidth Allocation Capabilities mechanisms can be exploited to deliver the required QoS while optimising the bandwidth utilization. This paper just deals with the design of innovative algorithms for scheduling and sending the resource requests queued on a EuroSkyWay [1,2] satellite terminal to a Traffic Resource Manager (TRM). The effectiveness of the defined mechanisms has been evaluated through computer simulations. Particularly, by considering different mixes of MPEG-2 traffic and HTTP traffic, the Average Waiting Time (AWT) of the requests and their Losses Percentage have been calculated and compared with those ones obtained using algorithms proposed in MAC layer EuroSkyWay specifications

    LIFT: a Local IPSec-aware Freezing Protocol to improve TCP Performance in Satellite Networks

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    In this paper a protocol, local to the satellite link, is defined in order to boost TCP performance in mobile integrated wired-satellite Internet. It has been conceived to help to overcome the well known retransmissions competition problem that arises when a satellite reliable link layer protocol is used to face satellite link errors. This protocol, called Local IPSec-aware Freezing proTocol (LIFT), has been designed to allow the satellite gateway, even in the presence of communications secured by IPSec, to freeze the TCP sender when it perceives a possible delay due to satellite channel conditions. The effectiveness of LIFT has been evaluated, using the ns-2 tool, in terms of Web page download mean time for a satellite mobile host. Simulation results have shown that the adoption of LIFT protocol provides substantial improvements in TCP performance

    An algorithm for controlling packet size in IEEE 802.16e networks

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    This paper proposes an algorithm to be used in IEEE 802.16e networks for adapting MAC PDU size to wireless channel behavior when ARQ is adopted at MAC layer. The algorithm is based on an analytical approach for dynamically evaluating the optimal packet size. The latter is derived from an expression of the ARQ protocol efficiency, obtained by exploiting a finite-state Markov error model which also takes into account Adaptive Modulation/Coding. The effectiveness of the designed algorithm in improving TCP performance has been evaluated

    MICROPILES TRIPODS SHIELDS (MTS) AS UNCONVENTIONAL BREAKERS FOR THE CONTROL OF MODERATELY RAPID EARTHFLOWS (SASSI NERI LANDSLIDE, NORTHERN APENNINES)

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    The paper deals with the idea, design and implementation of unconventional one-of-a-kind Micropiles Tripods Shields (MTS) intended to break and decelerate moderately rapid earthflows surges in the track zone of the Sassi Neri landslide (Nure Valley, Northern Apennines, Province of Piacenza, Italy). The MTS are inspired to floating anchors and “chevaux de fries” used in wartime. The basic elements are tripods of 193 mm diameter steel micropiles laid out at triangle, driven into the stable bedrock and emerging some meters aboveground. Each tripod consists of a vertical upslope central pile and two lateral oblique piles, linked by two transversal beams and connection plates aboveground. Multiple tripods are spaced along transversal rows to form Micropiles Tripods Shields (MTS) to advancing earthflows. The design of MTS has been based on field investigations such as boreholes and geophysics, that indicated a limited thickness of landslide deposits in the track zone where MTS have been installed. The forces resulting from active earthflows fronts have been estimated both with geotechnical and hydraulic computations. The analysis of vertical and transversal forces as well as bending moments acting on a single tripod versus the characteristic resistances was carried out using a bi-dimensional scheme with finite-elements software Plaxis, that indicated that the stress levels were compatible with the structural resistance of the tripods. The construction of MTS took place in 2018, involving working site preparation with partial lime-treatment of the surficial layers, underground micropiles drilling and installation, aboveground micropiles welding, tripods completion with connection beams and plates. Some tripods have been instrumented with load cells for monitoring earth pressures against micropiles, electric transducers for groundwater monitoring next to the piles, tiltmeters for tripods rotations and a total station for slope and tripods movements monitoring. Results show that the acceleration of slope movements corresponds to a generalized increase of pore water pressure at all the monitored tripods and to temporary slight tilting of the tripods which has so far being fully recovered when the landside slowed down and pressure decreased. This pioneering application indicates that once the characteristics of the earthflows are carefully considered, the depth to the bedrock in the installation zone is limited, and the logistical conditions in the field during construction are adequate, the MTS can be taken into consideration as a possible unconventional solution to break down and control moderately rapid earthflows

    Clinical Application of the New Prostate Imaging for Recurrence Reporting (PI-RR) Score Proposed to Evaluate the Local Recurrence of Prostate Cancer after Radical Prostatectomy

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    Simple Summary The aim of the new Prostate Imaging for Recurrence Reporting (PI-RR) is a standardization in reporting to assess the likelihood of relapse after radical prostatectomy. Our study documented an excellent inter-observer agreement in recurrence reporting when using the PI-RR score, demonstrating a wide reproducibility, thus supporting the wide use of the PI-RR score in the clinical practice. The diagnostic accuracy was 68.4%, with the detection rate influenced by the PSA values. Overall, the PI-RR score globally showed a higher detection rate than PET/CT scans for local recurrence. Background: We investigated the diagnostic accuracy of the new Prostate Imaging for Recurrence Reporting (PI-RR) score and its inter-observer variability. Secondly, we compared the detection rate of PI-RR and PET and analyzed the correlation between Prostate Specific Antigen (PSA) levels and the PI-RR score. Methods: We included in the analysis 134 patients submitted to multiparametric magnetic resonance imaging for suspected local recurrence. The images were independently reviewed by two radiologists, assigning a value from 1 to 5 to the PI-RR score. Inter-observer agreement and diagnostic accuracy of the PI-RR score (compared to histopathological data, available for 19 patients) were calculated. The detection rate was compared to those of choline PET/CT (46 patients) and PSMA PET/CT (22 patients). The distribution of the PSA values in relation to the PI-RR scores was also analyzed. Results: The accuracy of the PI-RR score was 68.4%. The reporting agreement was excellent (K = 0.884, p < 0.001). The PI-RR showed a higher detection rate than choline PET/CT (69.6% versus 19.6%) and PSMA PET-CT (59.1% versus 22.7%). The analysis of the PSA distribution documented an increase in the PI-RR score as the PSA value increased. Conclusion: The excellent reproducibility of the PI-RR score supports its wide use in the clinical practice to standardize recurrence reporting. The detection rate of PI-RR was superior to that of PET, but was linked to the PSA level
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