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The study reported in this paper concerns the temporal variation in the b-value of the Gutenberg–Richter frequency–magnitude law, applied to the earthquakes that struck Italy from 2009 to 2016 in the geographical areas of L'Aquila, the Emilia Region, and Amatrice–Norcia. Generally, the b-value varies from one region to another dependent on earthquake incidences. Higher values of this parameter are correlated to the occurrence of low-magnitude events spread over a wide geographical area. Conversely, a lower b-value may lead to the prediction of a major earthquake localized along a fault. In addition, it is observed that each seismic event has a different "occurrence time", which is a key point in the statistical study of earthquakes. In particular, its results are absolutely different for each specific event, and may vary from years to months or even just a few hours. Hence, both short- and long-term precursor phenomena have to be examined. Accordingly, the b-value analysis has to be performed by choosing the best time windows to study the foreshock and aftershock activities. [ABSTRACT FROM AUTHOR]

Detecting prestressed wire breakage in concrete bridges is essential for ensuring safety and longevity and preventing catastrophic failures. This study proposes a novel approach for wire breakage detection using Mel‐frequency cepstral coefficients (MFCCs) and back‐propagation neural network (BPNN). Experimental data from two bridges in Italy were acquired to train and test the models. To overcome the limited availability of real‐world training data, data augmentation techniques were employed to increase the data set size, enhancing the capability of the models and preventing over‐fitting problems. The proposed method uses MFCCs to extract features from acoustic emission signals produced by wire breakage, which are then classified by the BPNN. The results show that the proposed method can detect and classify sound events effectively, demonstrating the promising potential of BPNN for real‐time monitoring and diagnosis of bridges. The significance of this work lies in its contribution to improving bridge safety and preventing catastrophic failures. The combination of MFCCs and BPNN offers a new approach to wire breakage detection, while the use of real‐world data and data augmentation techniques are significant contributions to overcoming the limited availability of training data. The proposed method has the potential to be a generalized and robust model for real‐time monitoring of bridges, ultimately leading to safer and longer‐lasting infrastructure. [ABSTRACT FROM AUTHOR]

• Fracto-emission signals (Acoustic, Electromagnetic, and Neutron Emissions) might be used as earthquake precursors. • The experimental results are analyzed by means of a suitable multi-modal statistics. • Fracto-emissions anticipate the seismic event with a chronologically ordered shifting. • An innovative interpretation of the earthquake preparation zone is proposed. • The relationship between low magnitude earthquakes and Moon phases is investigated. Fracto-emission signals (Acoustic Emission AE, Electromagnetic Emission EME, and Neutron Emission NE), triggered by high-frequency pressure waves at the different scales, can be used as a promising tool for environmental protection against seismicity. So far, no reliable method has been developed yet for the successful application of earthquake prediction because the physical mechanism of earthquakes and precursors is at present poorly understood, as well as the estimation of the so-called "earthquake preparation zone". On the other hand, recent studies are also re-evaluating the possible correlation between seismic activity and lunar periodicity. Since July 2013 an in-situ experimental campaign has started at a gypsum mine located in Northern Italy, revealing the strong seismic forecasting potentialities of the fracto-emission peaks by means of a dedicated monitoring platform and a multi-modal statistical analysis. In the present paper, an innovative interpretation of the earthquake preparation area is proposed, and the new experimental evidences obtained at the gypsum mine are reported confirming the previous results (Carpinteri and Borla, 2017). Finally, the relationship between small magnitude earthquake swarms occurred in the surroundings of the mine and the Moon phases is also investigated. [ABSTRACT FROM AUTHOR]

[Display omitted] • Gypsum and Quartz compression specimens of different sizes are brought to complete failure. Only in the case of large specimens, neutron emissions are detected. • Unstable brittle behaviour is detected for micro-crystalline Gypsum and Quartz. • Stable strain-softening behaviour is detected for macro-crystalline Gypsum. • Chemical composition changes occurring on the fracture surfaces are consistently explained by Low-energy Nuclear Reactions (LENR), both fusion and fission. A correlation emerges between fusion nuclear reactions and strain-softening mechanical behaviour, as well as between fission nuclear reactions and brittle mechanical behaviour. Extensive experimental investigations were conducted on Gypsum and Quartz compression specimens of different sizes. They were brought to complete failure, showing two different failure modalities: (1) Very brittle loading drop for micro-crystalline Gypsum and Quartz; (2) Stable strain-softening behaviour for macro-crystalline Gypsum. All the tested specimens emitted acoustic and electromagnetic waves and the single events cumulated up to the peak load. On the other hand, neutron emissions were evident only for the largest specimens. The significant chemical composition changes occurring on the fracture surfaces are consistently explained by the assumption of Low-energy Nuclear Reactions (LENR), both fusion and fission. It is the first time that fusion reactions emerge from crushing tests, whereas fission reactions have already consistently explained the results related to other materials like the iron-rich natural rocks. Therefore, a correlation emerges between fusion nuclear reactions and strain-softening mechanical behaviour, as well as between fission nuclear reactions and brittle mechanical behaviour. [ABSTRACT FROM AUTHOR]

TeraHertz vibrations and pressure waves are produced at the nano-scale in solids and fluids by fracture and cavitation, respectively. They present a frequency that is close to the resonance frequency of the atomic lattices and an energy that is close to that of thermal neutrons. Original experiments performed on non-radioactive rocks under mechanical compression loading have shown repeatable neutron emissions in correspondence to micro- and macro-fracture. After these experiments, a considerable reduction in the iron content of the crushed rocks appears to be consistently counterbalanced by an increase in Al, Si, and Mg contents. At the same time, significant measurements of neutron emissions are observed at the Earth's Crust scale before and during seismic activity. In addition, several data coming from geochemistry and geomechanics have recently emphasized how tectonic activity should have been strictly connected to the most important changes in the Earth's Crust chemical composition over the last 4.5 Billion years. On these bases, the hypothesis of a new kind of low energy nuclear reactions finds confirmation and could be considered as a valid explanation for the geologic evolution of the Earth's Crust, Ocean, and Atmosphere. The same phenomenon appears to have occurred also in the chemical evolution of other planets of the Solar System like Mars, and of the Sun itself. [ABSTRACT FROM AUTHOR]

Three different forms of energy might be used as earthquake precursors for environmental protection against seismicity. At the tectonic scale, Acoustic Emission (AE) prevails, as well as Electro-Magnetic Emission (EME) at the intermediate scales, and Neutron Emission (NE) at the nano-scale. TeraHertz pressure waves are in fact produced at the last extremely small scale, and fracture experiments on natural rocks have recently demonstrated that these high-frequency waves are able to induce nuclear fission reactions with neutron and/or alpha particle emissions. Very important applications to earthquake precursors can be proposed. The authors present the results they are obtaining at a gypsum mine located in Northern Italy. In this mine, to avoid interference with human activities, the instrumental control units have been located at one hundred metres underground. The experimental results obtained from July 1st, 2013 to December 31, 2015 (five semesters) are analysed by means of a suitable multi-modal statistics. The experimental observations reveal a strong correlation between the three fracto-emission peaks (acoustic, electromagnetic, and neutron emissions) and the major earthquakes occurred in the surrounding areas. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study is to investigate radioprotection issues that must be addressed when dedicated accelerators for intraoperative radiotherapy (IORT) are used in operating rooms. Recently, a new version of a mobile IORT accelerator (LIAC™ Sordina SpA, Italy) with 12 MeV electron beam has been implemented. This energy is necessary in some specific pathology treatments to allow a better coverage of thick lesions. At an electron energy of 10 MeV, leakage and scattered x-ray radiation (stray radiation) coming from the accelerator device and patient must be considered. If the energy is greater than 10 MeV, the x-ray component will increase; however, the most meaningful change should be the addition of neutron background. Therefore, radiation exposure of personnel during the IORT procedure needs to be carefully evaluated. Methods: In this study, stray x-ray radiation was measured and characterized in a series of spherical projections by means of an ion chamber survey meter. To simulate the patient during all measurements, a polymethylmethacrylate (PMMA) slab phantom with volume 30×30×15 cm3 and density 1.19 g/cm3 was used. The PMMA phantom was placed along the central axis of the beam in order to absorb the electron beams and the tenth value layer (TVL) and half value layer (HVL) of scattered radiation (at 0°, 90°, and 180° scattering angles) were also measured at 1 m of distance from the phantom center. Neutron measurements were performed using passive bubble dosimeters and a neutron probe, specially designed to evaluate ambient dose equivalent H*(10). Results: The x-ray equivalent dose measured at 1 m along the beam axis at 12 MeV was 260 μSv/Gy. The value measured at 1 m at 90° scattering angle was 25 μSv/Gy. The HVL and TVL values were 1.1 and 3.5 cm of lead at 0°, and 0.4 and 1 cm at 90°, respectively. The highest equivalent dose of fast neutrons was found to be at the surface of the phantom on the central beam axis (2.9±0.6 μSv/Gy), while a lower value was observed below the phantom (1.6±0.3 μSv/Gy). The neutron dose equivalent at 90° scattering angle and on the floor plane on the beam axis below the beam stopper was negligible. Conclusions: Our data confirm that neutron exposure levels around the new dedicated IORT accelerator are very low. Mobile shielding panels can be used to reduce x-ray levels to below regulatory levels without necessarily providing permanent shielding in the operating room. [ABSTRACT FROM AUTHOR]

Acoustic emissions (AE) due to microcracking in solid materials permit the monitoring of fracture processes and the study of failure dynamics. As an alternative method of integrity assessment, measurements of electrical resistance can be used as well. In the literature, however, many studies connect the notion of criticality with AE originating from the fracture, but not with the changes in the electrical properties of materials. In order to further investigate the possible critical behavior of fracture processes in rocks and cement-based materials, we apply natural time (NT) analysis to the time series of AE and resistance measurements, recorded during fracture experiments on cement mortar (CM) and Luserna stone (LS) specimens. The NT analysis indicates that criticality in terms of electrical resistance changes systematically precedes AE criticality for all investigated specimens. The observed greater unpredictability of the CM fracture behavior with respect to LS could be ascribed to the different degree of material homogeneity, since LS (heterogeneous material) expectedly offers more abundant and more easily identifiable fracture precursors than CM (homogenous material). Non-uniqueness of the critical point by varying the detection threshold of cracking events is apparently due to finite size effects which introduce deviations from the self-similarity. [ABSTRACT FROM AUTHOR]