Non-local cooperative atomic motions that govern dissipation in amorphous tantala unveiled by dynamical mechanical spectroscopy

The mechanisms governing mechanical dissipation in amorphous tantala are studied at microscopic scale via Molecular Dynamics simulations, namely by mechanical spectroscopy in a wide range of temperature and frequency. We find that dissipation is associated with irreversible atomic rearrangements with a sharp cooperative character, involving tens to hundreds of atoms arranged in spatially extended clusters of polyhedra. Remarkably, at low temperature we observe an excess of plastically rearranging oxygen atoms which correlates with the experimental peak in the macroscopic mechanical losses. A detailed structural analysis reveals preferential connections of the irreversibly rearranging polyhedra, corresponding to edge and face sharing. These results might lead to microscopically informed design rules for reducing mechanical losses in relevant materials for structural, optical, and sensing applications

Port noise and complaints in the North Tyrrhenian sea and framework for remediation

Compared to the other relevant noise sources such as railways, roads, and airplanes, the regulation regarding port noise is lagging behind. The absence of specific laws is likely one of the main causes of the increasingly high number of complaints reported by the citizens living nearby the ports. At the same time, scientific literature concerning the impact of port noise and its mitigation is not so widespread and only a few studies are available at the moment. However, the volume of maritime traffic has increased in the last years and consequently, Port Authorities are required to assess the impact of port operations on the city soundscape without using specific directives or guidelines. In this context, the INTERREG Maritime programme projects RUMBLE, MON ACUMEN, and REPORT aim to fill this gap, by investigating the state-of-the-art of port noise in the north Tyrrhenian sea and developing helpful instruments. Data were collected via a survey sent to the Port Authorities, local environmental protection agencies and universities involved in the projects. The survey was focused on monitoring systems, previous measurement campaigns, noise maps, and citizens’ complaints already taken. The results confirmed both a lack of awareness among residents and authorities and the absence of actions aimed at reducing port noise. In this framework, the difficulties encountered by the Port Authorities in managing the ports sustainably are highlighted. An underestimation of citizens’ exposure to noise in port areas could be expected

Diffractive effects in spin-flip pp amplitudes and predictions for relativistic energies

We analyze the diffractive (Pomeron) contribution to pp spin-flip amplitude and discuss the possible scenarios for energies available at the Relativistic Heavy-Ion Collider (RHIC). In particular, we show that RHIC data will be instrumental in assessing the real contribution of diffraction to spin amplitudes.Comment: 11 pages, 12 Encapsulated PostScript files, LaTeX2e use

Stabilization of a p-u sensor mounted on a vehicle for measuring the acoustic impedance of road surfaces

The knowledge of the acoustic impedance of a material allows for the calculation of its acoustic absorption. Impedance can also be linked to structural and physical proprieties of materials. However, while the impedance of pavement samples in laboratory conditions can usually be measured with high accuracy using devices such as the impedance tube, complete in-situ evaluation results are less accurate than the laboratory results and is so time consuming that a full scale implementation of in-situ evaluations is practically impossible. Such a system could provide information on the homogeneity and the correct laying of an installation, which is proven to be directly linked to its acoustic emission properties. The present work studies the development of a measurement instrument which can be fastened through holding elements to a moving laboratory (i.e., a vehicle). This device overcomes the issues that afflict traditional in-situ measurements, such as the impossibility to perform a continuous spatial characterization of a given pavement in order to yield a direct evaluation of the surface’s quality. The instrumentation has been uncoupled from the vehicle’s frame with a system including a Proportional Integral Derivative (PID) controller, studied to maintain the system at a fixed distance from the ground and to reduce damping. The stabilization of this device and the measurement system itself are evaluated and compared to the traditional one

Pass-by characterization of noise emitted by different categories of seagoing ships in ports

In the light of sustainability, satisfactory living conditions is an important factor for people's positive feedback in their own living environment. Acoustic comfort and noise exposure should then be carefully monitored in all human settlements. Furthermore, it is already well-known that high or prolonged noise levels may lead to unwanted health effects. Unfortunately, while in the last decades scientists and public authorities have investigated the noise produced by roads, trains, and airports, not enough efforts have been spent in studying what happens around the coastal and port areas. Following the attention brought to the subject by recent European projects on noise in port areas, the present paper characterizes the sound power level and 1/3 octave band sound power spectrum of seagoing ships while moving at low speeds. Five different categories have been distinguished: Roll-on/roll-off (RORO), container ship, oil tanker, chemical tanker, and ferry. The analysis is based on a continuous noise measurement lasting more than three months, performed in the industrial canal of the port of Livorno (Italy). The resulting noise emissions are new and useful data that could be inserted in acoustic propagation models to properly assess the noise in the areas affected by port activities. Thus, the present work can act as a supporting tool in planning ship traffic in ports towards better sustainability

Plasduino: an inexpensive, general purpose data acquisition framework for educational experiments

Based on the Arduino development platform, Plasduino is an open-source data acquisition framework specifically designed for educational physics experiments. The source code, schematics and documentation are in the public domain under a GPL license and the system, streamlined for low cost and ease of use, can be replicated on the scale of a typical didactic lab with minimal effort. We describe the basic architecture of the system and illustrate its potential with some real-life examples.Comment: 11 pages, 10 figures, presented at the XCIX conference of the Societ\`a Italiana di Fisic

A sapphire monolithic differential accelerometer as core sensor for gravity gradiometric geophysical instrumentation

Gradiometric gravimetry is a survey technique widely used in geological structure investigation. This work demonstrates the feasibility of a new class of low frequency accelerometers for geodynamics studies and space applications. We present the design features of a new low noise single-axis differential accelerometer; the sensor is suitable to be used in a Gravity Gradiometer (GG) system for land geophysical survey and gravity gradient measurements. A resolution of 1 Eötvös (1 Eö=10−9s−2) at one sample per second is achievable in a compact, lightweight (less than 2 kg) portable instrument, operating at room temperature. The basic components of the sensor are two identical rigidly connected accelerometers separated by a 15-cm baseline vector and the useful signal is extracted as the subtraction of the two outputs, by means of an interferometric microwave readout system. The structure will be engraved in a monocrystal of sapphire by means of Computer-Numerically-Controlled (CNC) ultrasonic machining: the material was chosen because of its unique mix of outstanding mechanical and dielectric properties

MECHANICAL SHOT NOISE INDUCED BY CREEP IN SUSPENSION DEVICES

Abstract The sensitivity curve of a gravitational wave interferometric detector like VIRGO might be seriously limited by the mechanical shot noise induced by stationary creep in the heavily loaded mechanical suspension components (wires, spring blades, etc.). We quantify this effect and discuss possible improvements which could be implemented without major design alterations

Parameters affecting noise emitted by ships moving in port areas

Only recently has noise been considered in the assessment of the sustainability of port infrastructures, after decades of unawareness. INTERREG Maritime projects unveiled problems that have been neglected so far, such as the lack of proper regulation and noise exposure assessments for citizens. While it is true that a port area includes a huge variety of possible noise sources, very few of them have been characterized from an acoustical point of view. INTERREG projects have boosted research in the field, and previous studies have dealt with noise produced by moving ships in ports. The present work starts from a previous measurement campaign used to obtain broadband and 1/3-octave-band noise emissions of moving ships, and it aims to explain their uncertainties. More than a month’s worth of continuous acoustic measurements and video recordings were deeply analyzed in order to obtain an input database that is as precise as possible. A multiple regression analysis was performed in order to understand the influence that parameters such as minimum distance, speed, and draught have on ships’ noise emissions, which were calculated using pass-by measurements, with a special focus on ferries. The minimum distance of each ship’s passage from the microphone was measured using a video recording with an innovative methodology, providing results with 3 m of uncertainty. Knowing which parameter is more influential would help in planning proper measurements for monitoring or for drafting correct guidelines. Draught was determined to be uninfluential in ferries’ noise emissions, while the minimum distance and speed relations were estimated and accounted for in the calculation of a refined sound power level. From a spectrum point of view, the frequencies from 500 Hz to 2.5 kHz were determined to be those that contributed the most to the noise produced by the transit of a ship, and they vary with speed. With the studied corrections, different ferry models resulted in similar noise emissions. The standard deviation of noise emitted was reduced by 0.5 dB (A), and the average was also improved by positioning the ships’ flow at the correct average minimum distance. Furthermore, the right placement of a source is also important in the acoustic mapping phase for a correct evaluation of the propagation of noise at a distance. The use of more precise input data is important for improving the output of acoustic propagation models during the assessment of port noise in the surrounding areas

Source characterization guidelines for noise mapping of port areas

Maritime transport for both passengers and freight is continuously increasing and, consequently, the global attention toward its sustainability is growing. Ships offer advantages in terms of environmental impact compared to other transportation systems but the increasing traffic volume is expected to increase pollutants. Noise produced in port areas has been neglected for too long, until the INTERREG Maritime programme Italy-France 2014\u20132020 has brought to light how citizen complaints are emerging for some of the main ports in the Mediterranean. However, port noise prevention and management is difficult as knowledge on specific sources is very limited in the literature. Furthermore, on field measurements are difficult to be performed given the complexity of the port area, where multiple types of sound emitters mix and confuse each other. Noise maps represent the first important step in order to align ports to the requirements set by the Environmental Noise Directive to the transportation infrastructures. Once computed, they are an excellent tool supporting port management towards the reduction of citizens\u2019 noise exposure while ensuring traffic growth. The present paper reports a guideline for the characterization of noise sources needed as inputs for the noise maps, as developed in the framework of the INTERREG Maritime programme Italy-France 2014\u20132020. On the basis of the current state of the art, a procedure has been elaborated for different categories of noise sources acting in port, ranging from stationary to moving ships, from mooring operations to loading/unloading operations, from industrial activities to road and railway traffic