Experimental and computational investigation of a new solar integrated collector storage system

The paper discusses a combined experimental-numerical analysis of an innovative solar thermal device to be used as an Integrated Collector Storage (ICS) system providing domestic hot water. In this equipment the collector acts also as a storage unit, without requiring an external vessel. Due to its simple configuration, the ICS device was successfully used in several circumstances, especially in extreme situations such as in post-earthquake tent cities or to reach remote users in Africa. In order to assess the efficiency of this collector, the draw-off process was investigated measuring the value of the mean temperature of the water discharging from the tap as cold water filled the collector. In the present configuration the draw-off is not completely optimised and a detailed analysis was carried out in order to investigate the mixing of cold and hot water in the solar collector during the discharge phase. A series of thermocouples was placed in selected positions around the shield of the collector to investigate the evolution of the near wall temperature. Furthermore, a numerical analysis based on Large-Eddy Simulation (LES) of the mixing process inside the collector was carried out using an open source, in-house, finite-volume computational code. Even if some restrictive hypotheses were made on the thermal boundary conditions and the absence of stratification, the LES results gave interesting findings to improve the collector performance

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

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

A flexible algorithm for detecting challenging moving objects in real-time within IR video sequences

Real-time detecting moving objects in infrared video sequences may be particularly challenging because of the characteristics of the objects, such as their size, contrast, velocity and trajectory. Many proposed algorithms achieve good performances but only in the presence of some specific kinds of objects, or by neglecting the computational time, becoming unsuitable for real-time applications. To obtain more flexibility in different situations, we developed an algorithm capable of successfully dealing with small and large objects, slow and fast objects, even if subjected to unusual movements, and poorly-contrasted objects. The algorithm is also capable to handle the contemporary presence of multiple objects within the scene and to work in real-time even using cheap hardware. The implemented strategy is based on a fast but accurate background estimation and rejection, performed pixel by pixel and updated frame by frame, which is robust to possible background intensity changes and to noise. A control routine prevents the estimation from being biased by the transit of moving objects, while two noise-adaptive thresholding stages, respectively, drive the estimation control and allow extracting moving objects after the background removal, leading to the desired detection map. For each step, attention has been paid to develop computationally light solution to achieve the real-time requirement. The algorithm has been tested on a database of infrared video sequences, obtaining promising results against different kinds of challenging moving objects and outperforming other commonly adopted solutions. Its effectiveness in terms of detection performance, flexibility and computational time make the algorithm particularly suitable for real-time applications such as intrusion monitoring, activity control and detection of approaching objects, which are fundamental task in the emerging research area of Smart City

A CFD-based virtual test-rig for rotating heat exchangers

Rotating heat exchangers are used in steel industry, air conditioning and thermal power plants to pre-heat air used in steam generators or for waste heat recovery. Here we focus on a rotating heat exchanger on a so-called Ljungström arrangement operated in thermal power plants to pre-heat the air fed to the steam generators. In these devices the heat exchange between two fluids is achieved through a rotating matrix that gets in contact alternatively with the two fluid streams and acts as a thermal accumulator. To increase the heat capacity and the overall exchange surface, the rotating matrix is filled by a series of folded metal sheets. In the paper we de-scribe a methodology to account for the effects of the Ljungström in a virtual test-rig implemented in a Computational Fluid Dynamics environment. To this aim, a numerical model based on the work of Molinari and Cantiano was derived and implemented in the OpenFOAM library. RANS numerical results were compared with those of a mono-dimensional tool used by ENEL to design Ljungström heat exchangers and validated against available measurements in a real configuration of a thermal power plant

On the Evaluation of Sequential Machine Learning for Network Intrusion Detection

Recent advances in deep learning renewed the research interests in machine learning for Network Intrusion Detection Systems (NIDS). Specifically, attention has been given to sequential learning models, due to their ability to extract the temporal characteristics of Network traffic Flows (NetFlows), and use them for NIDS tasks. However, the applications of these sequential models often consist of transferring and adapting methodologies directly from other fields, without an in-depth investigation on how to leverage the specific circumstances of cybersecurity scenarios; moreover, there is a lack of comprehensive studies on sequential models that rely on NetFlow data, which presents significant advantages over traditional full packet captures. We tackle this problem in this paper. We propose a detailed methodology to extract temporal sequences of NetFlows that denote patterns of malicious activities. Then, we apply this methodology to compare the efficacy of sequential learning models against traditional static learning models. In particular, we perform a fair comparison of a `sequential' Long Short-Term Memory (LSTM) against a `static' Feedforward Neural Networks (FNN) in distinct environments represented by two well-known datasets for NIDS: the CICIDS2017 and the CTU13. Our results highlight that LSTM achieves comparable performance to FNN in the CICIDS2017 with over 99.5\% F1-score; while obtaining superior performance in the CTU13, with 95.7\% F1-score against 91.5\%. This paper thus paves the way to future applications of sequential learning models for NIDS

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

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

Functional Role of the Third Cytoplasmic Loop in Muscarinic Receptor Dimerization

By means of the expression of two chimeric receptors, alpha2/m3 and m3/alpha2, in which the carboxyl-terminal receptor portions, containing transmembrane (TM) domains VI and VII, were exchanged between the alpha2C adrenergic and the m3 muscarinic receptor, Maggio et al. (Maggio, R., Vogel, Z., and Wess, J. (1993) Proc. Natl. Acad. Sci. U. S. A. 90, 3103-31073) demonstrated that G protein-linked receptors are able to interact functionally with each other at the molecular level to form (hetero)dimers. In the present study we tested the hypothesis that interaction between receptors might depend on the presence of a long third intracellular (i3) loop and that shortening this loop could impair the capability of receptors to form dimers. To address this question, we initially created short chimeric alpha2 adrenergic/m3 muscarinic receptors in which 196 amino acids were deleted from the i3 loop (alpha2/m3-short and m3/alpha2-short). Although co-transfection of alpha2/m3 and m3/alpha2 resulted in the appearance of specific binding, the co-expression of the two short constructs (alpha2/m3-short and m3/alpha2-short), either together or in combination, respectively, with m3/alpha2 and alpha2/m3 did not result in any detectable binding activity. In another set of experiments, a mutant m3 receptor, m3/m2(16aa), containing 16 amino acids of the m2 receptor sequence at the amino terminus of the third cytoplasmic loop, which was capable of binding muscarinic ligands but was virtually unable to stimulate phosphatidylinositol hydrolysis, was also mutated in the i3 loop, resulting in the m3/m2(16aa)-short receptor. Although co-transfection of m3/m2(16aa) with a truncated form of the m3 receptor (m3-trunc, containing an in frame stop codon after amino acid codon 272 of the rat m3 sequence) resulted in a considerable carbachol-stimulated phosphatidylinositol breakdown, the co-transfection of m3/m2(16aa)-short with the truncated form of the m3 receptor did not result in any recovery of the functional activity. Thus, these data suggest that intermolecular interaction between muscarinic receptors, involving the exchange of amino-terminal (containing TM domains I-V) and carboxyl-terminal (containing TM domains VI and VII) receptor fragments depends on the presence of a long i3 loop. One may speculate that when alternative forms of receptors with a different length of the i3 loop exist, they could have a different propensity to dimerize

The Paired Activation of the Two Components of the Muscarinic M3 Receptor Dimer Is Required for Induction of ERK1/2 Phosphorylation *

Muscarinic M(3) receptors stimulate ERK1/2, the mitogen-activated protein kinase pathway. A mutant of the muscarinic M(3) receptor in which most of the third intracellular (i3) loop had been deleted (M(3)-short) completely lost the ability to stimulate the ERK1/2 phosphorylation in COS-7 cells. This loss was evident despite the fact that the receptor was able to couple efficiently to the phospholipase C second messenger pathway. In co-transfected cells, M(3)-short greatly reduced the ability of M(3) to activate ERK1/2. In another set of experiments we tested the ability of a mutant M(3)/M(2)(16aa) receptor, in which the first 16 amino acids of the i3 loop of the M(3) receptor were replaced with the corresponding segment of the muscarinic M(2) receptor to stimulate ERK1/2 phosphorylation. This mutant is not coupled to Galpha(q), but it is weakly coupled to Galpha(i). Despite its coupling modification this receptor was able to stimulate ERK1/2 phosphorylation. Again, M(3)-short greatly reduced the ability of M(3)/M(2)(16aa) to activate ERK1/2 in co-transfected cells. Similar results were obtained in stable-transfected Chinese hamster ovary (CHO) cells lines. In CHO M(3) cells carbachol induced a biphasic increase of ERK1/2 phosphorylation; a first increase at doses as low as 0.1 microm and a second increase starting from 10 microm. In CHO M(3)-short and in double-transfected CHO M(3)/M(3)-short cells we observed only the lower doses increase of ERK1/2 phosphorylation; no further increase was observed up to 1 mm carbachol. This suggests that in double-transfected CHO cells M(3)-short prevents the effect of the higher doses of carbachol on the M(3) receptor. In a final experiment we tested the ability of co-transfected chimeric alpha(2)/M(3) and M(3)/alpha(2) receptors to activate the ERK1/2 pathway. When given alone, carbachol and, to a lesser extent, clonidine, stimulated the coupling of the co-transfected chimeric receptors to the phospholipase C second messenger pathway, but they were unable to stimulate ERK1/2 phosphorylation. On the contrary, a strong stimulation of ERK1/2 phosphorylation was observed when the two agonists were given together despite the fact that the overall increase in phosphatidylinositol hydrolysis was not dissimilar from that observed in cells treated with carbachol alone. Our data suggest that the activation of the ERK1/2 pathway requires the coincident activation of the two components of a receptor dimer

Design and verification of a micro wells turbine for Mediterranean operations

In the framework of the Poseidone Project we have designed a Wells turbine for Mediterranean operations. Here we present RANS computations carried out with OpenFOAM at different operating conditions. Rotor-stator interaction was synthetized with MRF approach and RANS closure relied on the cubic eddy viscosity closure of Lien et al. The virtual test rig reproduced the ISO conditions of the laboratory and was able to correctly predict torque and efficiency at different operations. Computations moreover allowed to acquire information on the threedimensional velocity and pressure field that develops inside the Wells turbine. The aim was to have an insight on the secondary motions and on the possible stall mechanism that characterize the device at low flow rates. Results were successfully validated against experimental measures