Ultrasonic measurements for assessing the elastic parameters of two-component grout used in full-face mechanized tunnelling

The use of shield machines and instantaneous segment linings for tunnel construction is one of the most used tunnelling methods today. Despite a large number of applications in different tunnelling projects all around the world, knowledge of the behaviour of two-component grout is quite limited, mainly due to the fast hardening process that inhibits using the classic approach for concrete characterization. In the present work, an innovative approach based on ultrasonic measurements is introduced, aimed to characterize the elastic properties of this innovative backfilling material. Specifically, ultrasonic pulse velocity was applied to two-component grout samples to describe the interesting and fast evolution of the material from the mixing phase until 6 months of curing using geophysics parameters. The dynamic Young’s modulus (E) and the dynamic shear modulus (G) exhibited a clear increasing trend, starting from values of a few tens of MPa to final values equal to 1000 MPa and 340 MPa, respectively. The Poisson’s ratio (ν), close to the value of incompressible materials (0.5) at the short curing time, exhibited a decreasing trend, reaching roughly 0.445 after 3 months of curing

Detection of Obfuscation Techniques in Android Applications

Current signature detection mechanisms can be easily evaded by malware writers by applying obfuscation techniques. Employing morphing code techniques, attackers are able to generate several variants of one malicious sample, making the corresponding signature obsolete. Considering that the signature definition is a laborious process manually performed by security analysts, in this paper we propose a method, exploiting static analysis and Machine Learning classification algorithms, to identify whether a mobile application is modified by means of one or more morphing techniques. We perform experiments on a real-world dataset of Android applications (morphed and original), obtaining encouraging results in the obfuscation technique(s) identification

PiCo: High-performance data analytics pipelines in modern C++

In this paper, we present a new C++ API with a fluent interface called PiCo (Pipeline Composition). PiCo’s programming model aims at making easier the programming of data analytics applications while preserving or enhancing their performance. This is attained through three key design choices: 1) unifying batch and stream data access models, 2) decoupling processing from data layout, and 3) exploiting a stream-oriented, scalable, efficient C++11 runtime system. PiCo proposes a programming model based on pipelines and operators that are polymorphic with respect to data types in the sense that it is possible to reuse the same algorithms and pipelines on different data models (e.g., streams, lists, sets, etc.). Preliminary results show that PiCo, when compared to Spark and Flink, can attain better performances in terms of execution times and can hugely improve memory utilization, both for batch and stream processing.Author's copy (postprint) of C. Misale, M. Drocco, G. Tremblay, A.R. Martinelli, M. Aldinucci, PiCo: High-performance data analytics pipelines in modern C++, Future Generation Computer Systems (2018), https://doi.org/10.1016/j.future.2018.05.03

Numerical study of compressor fouling mechanism based on Eulerian-Eulerian approach

AbstractThe paper describes a fluid dynamic numerical model to study the fouling mechanism for turbomachines (such as large gas turbines and small turbochargers). For this purpose, the gas-particle behaviour over a compressor blade is modelled using an open source CFD tool, OpenFOAM®. Through this model, two-fluid implicit equations system, with Eulerian-Eulerian approach is considered. This approach uses RANS turbulent models and also takes into account the particle fluid interactions. Applying Johnson-Kendal-Robert (JKR) theory, the particle deposition over the blade surface is predicted. According to the simulation results, there are certain regions which are facing the huge amount of deposition. The surfaces of these regions are prone to form an almost thick layer of sticked particles and affect the boundary layers and blade aerodynamics significantly. In order to capture this effect, a model to predict the deformation of the boundary with respect to deposition rate is also introduced

Unimolecular nucleophilic substitution (S N 1): Structural reactivity evidenced by colored acid-base indicators

The different reactivities between 1°, 2°, and 3° butyl chlorides by the unimolecular nucleophilic substitution (S N 1) mechanism were easily observed at 60 °C by a solvolysis reaction in ethanol with ether formation. The hydrogen ion from the byproduct HCl reacted with an acid-base indicator such as methyl red to induce a color change. At room temperature, the addition of AgNO 3 was used to detect the released chloride ion by AgCl precipitation. The reactivity order (3° > 2° ≫1°) was visually confirmed by both a color change in an indicator and precipitate formation by these safe, quick, and easy assays.Fil: Castro Godoy, Willber David. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Química Orgánica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Argüello, Juan Elias. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Química Orgánica; ArgentinaFil: Martinelli, Marisa. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Química Orgánica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Caminos, Daniel Alberto. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Química Orgánica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentin

Semi-Rigid (Aminomethyl) Piperidine-Based Pentadentate Ligands for Mn(II) Complexation

Two pentadentate ligands built on the 2-aminomethylpiperidine structure and bearing two tertiary amino and three oxygen donors (three carboxylates in the case of AMPTA and two carboxylates and one phenolate for AMPDA-HB) were developed for Mn(II) complexation. Equilibrium studies on the ligands and the Mn(II) complexes were carried out using pH potentiometry, 1H-NMR spectroscopy and UV-vis spectrophotometry. The Mn complexes that were formed by the two ligands were more stable than the Mn complexes of other pentadentate ligands but with a lower pMn than Mn(EDTA) and Mn(CDTA) (pMn for Mn(AMPTA) = 7.89 and for Mn(AMPDA-HB) = 7.07). 1H and 17O-NMR relaxometric studies showed that the two Mn-complexes were q = 1 with a relaxivity value of 3.3 mM-1 s-1 for Mn(AMPTA) and 3.4 mM-1 s-1 for Mn(AMPDA-HB) at 20 MHz and 298 K. Finally, the geometries of the two complexes were optimized at the DFT level, finding an octahedral coordination environment around the Mn2+ ion, and MD simulations were performed to monitor the distance between the Mn2+ ion and the oxygen of the coordinated water molecule to estimate its residence time, which was in good agreement with that determined using the 17O NMR data

Life history traits and historical comparison of blue whiting (Micromesistius poutassou) growth performance from the western Pomo/Jabuka Pits area (central Adriatic Sea)

Although fishing is considered the primary cause of the decline in fish populations, increasing evidence of the significant role of climate change has been provided recently in the Mediterranean Sea, which shows one of the highest warming trends in the world. In this area, the most important environmental driver is represented by the increase in seawater temperature. Though several studies have addressed the effects of sea warming on thermophilic species, little attention has been paid to cold-water species. Among these, blue whiting (Micromesistius poutassou) constitutes one of the most important traditional fisheries resources in the northern part of the basin, particularly in the central Adriatic Sea. This area has experienced intense fishing exploitation by the Italian and Croatian fishing fleets. Since 2015, the Pomo/Jabuka Pits area, the fleets' main fishing ground, has been subject to a series of fishing regulations over time and space. In the present study, we investigated the age structure and growth performance (by means of otoliths) of blue whiting, comparing samples collected during 1985-86 and 2020-21 in the Pomo/Jabuka Pits. Our results show that the 2020-21 blue whiting specimens had a lower length-at-age compared to 1985-86. The asymptotic length estimate decreased from 29 cm TL in 1985-86 to 25 cm TL in 2020-21. The pattern observed might be related to a modification in the cold and dense water formation dynamics in the northern Adriatic Sea, as a consequence of climate change, resulting in higher temperatures and lower nutrient and oxygen exchange, which may have hampered the optimal growth of the species. Moreover, data on the historical trend of landings from the Adriatic Sea reveals a clear decline in catches starting from 2000 onwards. Although the introduction of a fishing ban in the Pomo/Jabuka Pits was an important milestone, the abundance of this species in the area remains at low levels, highlighting a potentially alarming situation for the stock of blue whiting in the central Adriatic Sea