SISMIKO:emergency network deployment and data sharing for the 2016 central Italy seismic sequence

At 01:36 UTC (03:36 local time) on August 24th 2016, an earthquake Mw 6.0 struck an extensive sector of the central Apennines (coordinates: latitude 42.70° N, longitude 13.23° E, 8.0 km depth). The earthquake caused about 300 casualties and severe damage to the historical buildings and economic activity in an area located near the borders of the Umbria, Lazio, Abruzzo and Marche regions. The Istituto Nazionale di Geofisica e Vulcanologia (INGV) located in few minutes the hypocenter near Accumoli, a small town in the province of Rieti. In the hours after the quake, dozens of events were recorded by the National Seismic Network (Rete Sismica Nazionale, RSN) of the INGV, many of which had a ML > 3.0. The density and coverage of the RSN in the epicentral area meant the epicenter and magnitude of the main event and subsequent shocks that followed it in the early hours of the seismic sequence were well constrained. However, in order to better constrain the localizations of the aftershock hypocenters, especially the depths, a denser seismic monitoring network was needed. Just after the mainshock, SISMIKO, the coordinating body of the emergency seismic network at INGV, was activated in order to install a temporary seismic network integrated with the existing permanent network in the epicentral area. From August the 24th to the 30th, SISMIKO deployed eighteen seismic stations, generally six components (equipped with both velocimeter and accelerometer), with thirteen of the seismic station transmitting in real-time to the INGV seismic monitoring room in Rome. The design and geometry of the temporary network was decided in consolation with other groups who were deploying seismic stations in the region, namely EMERSITO (a group studying site-effects), and the emergency Italian strong motion network (RAN) managed by the National Civil Protection Department (DPC). Further 25 BB temporary seismic stations were deployed by colleagues of the British Geological Survey (BGS) and the School of Geosciences, University of Edinburgh in collaboration with INGV. All data acquired from SISMIKO stations, are quickly available at the European Integrated Data Archive (EIDA). The data acquired by the SISMIKO stations were included in the preliminary analysis that was performed by the Bollettino Sismico Italiano (BSI), the Centro Nazionale Terremoti (CNT) staff working in Ancona, and the INGV-MI, described below

Sphere rolling on a moving surface: Application of the fundamentalequation of constrained motion

This paper deals with the general formulation of the problem of a rigid sphere rolling under gravity on an arbitrarily prescribed surface that is moving in an arbitrarily prescribed manner. This is accomplished by using a recently developed modeling paradigm, which is encapsulated in a systematic general three-step procedure. The first step develops the equations of motion of the so-called unconstrained system in which the sphere is decoupled from the surface on which it moves. The novelty in this paper is the inclusion of a zero-mass particle and its associated coordinates in the unconstrained description of the system, whose equations of are trivial to write down since it is assumed that all the coordinates are independent of one another. However, this leads to a singular mass matrix. The second step involves the statement of the constraints that (a) cause the sphere to roll on the surface without slip, (b) cause the zero-mass particle to bind to the surface and to become the point of contact between the sphere and the surface, and (c) ensure that the quaternion describing the rotational motion of the sphere is a unit quaternion. The third step involves the direct application of the Udwadia–Phohomsiri equation that generates the equations of motion for the system. Simulations of the motion of a sphere rolling on a moving parabolic surface are shown illustrating the ease and efficacy with which both the formulation and the numerical results can be obtained. The systematic modeling procedure used here to study the dynamics of the rolling sphere along with the use of a zero-mass particle opens up new ways for modeling and simulating the dynamical behavior of complex multi-body systems

Investigation on the mechanical properties of MRE compounds

This paper describes an experimental investigation conducted on magneto-rheological elastomers (MREs) with the aim of adopting these materials to make mounts to be used as vibration isolators. These materials, consisting of an elastomeric matrix containing ferromagnetic particles, are considered to be smart materials, as it is possible to control their mechanical properties by means of an applied magnetic field. In the first part of the paper, the criteria adopted to define the characteristics of the material and the experimental procedures for making samples are described. The samples are subjected to a compressive static test and are then, adopting a testing machine specially configured, tested for shear periodic loads, each characterized by a different constant compressive preload. The testing machine is equipped with a coil, with which it is possible to vary the intensity of the magnetic field crossing the sample during testing to evaluate the magneto-rheological effect on the materials’ characteristics in terms of stiffness and damping

A vibration isolator based on magneto-rheological elastomer

The paper presents an investigation about a magneto-rheological elastomeric (MRE) pad to be adopted as seismic semi-active isolator for lightweight structures. MRE pad may change its stiffness if immersed in a magnetic field. This characteristic allows to real time shift the fundamental frequency of the isolated structure. In this way it is possible to drive away the structure fundamental frequency from the exciting frequencies and therefore to reduce accelerations induced by the ground motion. The isolator includes a ball transfer unit (BTU) to sustain the vertical load so that MRE pad must only exert horizontal restoring forces and it may have a slender geometry without concern regarding bucklin

Experimental Investigation to Enhance Performances of MRE in Energy Harvesting

stract. The so-called “Smart Systems” are increasingly wide-spread impacting extremely different fields, that range from production systems to transport systems up to instrumented dress. For the correct functioning of these systems, it is necessary to use sensors that must be powered. When, for environmental or technical reasons it is not possible to employ cables or batteries, the sensors must be self-powered. The set of technologies used to transform energy dispersed in the environment into electrical energy useful for powering the sensors is called Energy Harvesting (EH). In this paper is investigated the use of Magnetorheological elastomers (MREs) as transducer for the conversion of mechanical vibration energy in electrical energy. The energy conversion, based on the “Villari Effect”, is obtained from the strain of a MRE pad immersed in a magnetic field. The device must also include a magnetic circuit and a coil. The behaviour of two types of specimens is investigated: the first made only with rubber while the second composed by rubber and thin iron sheets. The study made by means of an experimental test rig showed a noticeable increase of output voltage when the iron discs are also used. The paper represents a contribution to researches in the field of Sustainable Development Goals number seven: Affordable and Clean Energy