The talk with present the key results of the IPCC Working Group III 5th assessment report. Concluding four years of intense scientific collaboration by hundreds of authors from around the world, the report responds to the request of the world's governments for a comprehensive, objective and policy neutral assessment of the current scientific knowledge on mitigating climate change. The report has been extensively reviewed by experts and governments to ensure quality and comprehensiveness.

Climate change 2014 - Mitigation of climate change

This article reviews acoustic microfiuidics: the use of acoustic fields, principally ultrasonics, for application in microfiuidics. Although acoustics is a classical field, its promising, and indeed perplexing, capabilities in powerfully manipulating both fluids and particles within those fluids on the microscale to nanoscale has revived interest in it. The bewildering state of the literature and ample jargon from decades of research is reorganized and presented in the context of models derived from first principles. This hopefully will make the area accessible for researchers with experience in materials science, fluid mechanics, or dynamics. The abundance of interesting phenomena arising from nonlinear interactions in ultrasound that easily appear at these small scales is considered, especially in surface acoustic wave devices that are simple to fabricate with planar lithography techniques common in microfluidics, along with the many applications in microfluidics and nanofluidics that appear through the literature.

/pdf/microscale-acoustofluidics-microfluidics-driven-via-5bet39j13p.pdf

Microscale acoustofluidics: Microfluidics driven via acoustics and ultrasonics

Renewable energy sources have gained much attention due to the recent energy crisis and the urge to get clean energy. Among the main options being studied, wind energy is a strong contender because of its reliability due to the maturity of the technology, good infrastructure and relative cost competitiveness. In order to harvest wind energy more efficiently, the size of wind turbines has become physically larger, making maintenance and repair works difficult. In order to improve safety considerations, to minimize down time, to lower the frequency of sudden breakdowns and associated huge maintenance and logistic costs and to provide reliable power generation, the wind turbines must be monitored from time to time to ensure that they are in good condition. Among all the monitoring systems, the structural health monitoring (SHM) system is of primary importance because it is the structure that provides the integrity of the system. SHM systems and the related non-destructive test and evaluation methods are discussed in this review. As many of the methods function on local damage, the types of damage that occur commonly in relation to wind turbines, as well as the damage hot spots, are also included in this review.

https://iopscience.iop.org/article/10.1088/0957-0233/19/12/122001/pdf

Structural health monitoring for a wind turbine system: a review of damage detection methods

The sensitivity method in finite element model updating: A tutorial

The sensitivity method in finite element model updating: A tutorial (vol 25, pg 2275, 2010)

FEM based design of experiment for train wheelset diagnostics by laser ultrasonics.

In rotating machinery variations of modal parameters with rotation speed may be extremely important in particular if very light and undamped structures are taken into account, like helicopters rotors or wind turbines. The relation between natural frequencies and rotation speed is expressed in the form of Campbell diagrams. However it could be required to know also the deviation of operational or mode shapes. In several cases it is not possible to fully control the rotating speed of the machine and only coast-down tests can be performed. Such kind of tests is often fast due to the reduced inertia of rotors: for this reason, an experimental technique able to determine Operational Deflection Shapes (ODSs) in short time and with sufficient accuracy, appears very promising. Moreover coast-down processes are very difficult to be controlled, they causing unsteady vibrations. The need to obtain ODSs from coast-down experiments requires the measurement over a large number of points and therefore a very efficient approach for the rotation control and synchronous acquisition must be developed. In this paper a continuous scanning system operating on rotating structures has been developed, that allows to measure ODS and natural frequencies excited in rotating conditions at different rotation speed during a coast down. This techniques has been tested on a laboratory test bench and compared with traditional Experimental Modal Analysis (EMA) results obtained in non-rotating conditions and with data from Tracking Laser Doppler Vibrometry (TLDV) operating in coast down and at consecutive constant rotation speeds (i.e. each measurement was performed in steady conditions). EMA and TLDV have been performed over a grid of points in order to have ODSs with adequate spatial resolution, it requiring long measurement time. However these data has been used as reference to validate the continuous scanning approach.

Characterization of Rotating Structures in Coast-down by means of Continuous Tracking Laser Doppler Vibrometer

In the recent past, hyper-spectral imaging has found widespread application in forensic science, performing both geometric characterization of biological traces and trace classification by exploiting their spectral emission. Methods proposed in the literature for blood stain analysis have been shown to be effectively limited to collaborative surfaces. This proves to be restrictive in real-case scenarios. The problem of the substrate material and color is then still an open issue for blood stain analysis. This paper presents a novel method for blood spectra correction when contaminated by the influence of the substrate, exploiting a neural network-based approach. Blood stains hyper-spectral images deposited on 12 different substrates for 12 days at regular intervals were acquired via a hyper-spectral camera. The data collected were used to train and test the developed neural network model. Starting from the spectra of a blood stain deposited in a generic substrate, the algorithm at first recognizes whether it is blood or not, then allows to obtain the spectra that the same blood stain, at the same time, would have on a reference white substrate with a mean absolute percentage error of 1.11%. Uncertainty analysis has also been performed by comparing the ground truth reflectance spectra with the predicted ones by the neural model.

https://www.mdpi.com/1424-8220/22/19/7311/pdf?version=1664265799

Correction of Substrate Spectral Distortion in Hyper-Spectral Imaging by Neural Network for Blood Stain Characterization

Localization and quantification of noise sources are important to fulfill customer and regulation requirements in a such competitive sector like automotive manufacturing. Wind tunnel testing and acoustic mapping techniques based on microphone arrays can provide accurate information on these aspects. However, it is not straightforward to get source positions and strengths in these testing conditions. In fact, the car is a 3D object that radiates noise from different parts simultaneously, involving different noise generation mechanisms such as tire noise and aerodynamic noise. Commonly, acoustic maps are produced on a 3D surface that envelopes the objects. However, this practice produces misleading and/or incomplete results, as acoustic sources can be generated outside the surface. When the hypothesis of sources on the model surface is removed, additional issues arise. In this paper, we propose exploiting an inverse method tailored to a volumetric approach. The aim of this paper is to investigate the issues to face when the method is applied to automotive wind tunnel testing. Two different kinds of problem must be considered: On the one hand, the results of inverse methods are strongly influenced by the problem definition, while, on the other hand, experimental conditions must be taken into account to get accurate results. These aspects have been studied making use of simulated experiments. Such a controlled simulation environment, by contrast to a purely experimental case, enables accurate assessment of both the localization and quantification performance of the proposed method. Finally, a set of scores is defined to evaluate the resulting maps with objective metrics.

https://www.mdpi.com/2076-3417/11/7/3241/pdf

3D Acoustic Mapping in Automotive Wind Tunnel: Algorithm and Problem Analysis on Simulated Data

Phased Array aeroacoustic measurements are gaining an increasing interest in automotive and aeronautic design. This paper describes the beamforming approaches used for characterizing acoustic sources on an counter rotating open rotor (CROR) installed on a 1/7th scale model of an advanced regional air-craft design. The tests were conducted in a large Low Speed Wind Tunnel (WT) at The Pininfarina Aerodynamic and Aeroacoustic Research Center in Turin, Italy, within the framework of the FP7 EU Clean-Sky WENEMOR (Wind tunnel tests for the Evaluation of the installation effects of Noise EMissions of an Open Rotor advanced regional aircraft) project. Three planar microphone arrays were installed in Pininfarina WT: a wheel array (3m diameter) placed at the ceiling of the WT (Top), a half-wheel array positioned broadside and parallel to the axis of the open rotor (Lateral) and a spiral array (2.5m aperture) placed upstream the blade plane and at an angle of 10 degrees to the blade plane (Upstream). Measurements were performed for a variety of aircraft geometries (involving different fuselage and rotor configurations), angles of attack and wind speeds. Preliminary beamforming results obtained processing the Top and Lateral arrays are presented and discussed.

/pdf/aeroacoustic-source-localization-on-open-rotor-aircraft-4jiptu1qff.pdf

Milena Martarelli

Papers

FEM based design of experiment for train wheelset diagnostics by laser ultrasonics.

Characterization of Rotating Structures in Coast-down by means of Continuous Tracking Laser Doppler Vibrometer

Correction of Substrate Spectral Distortion in Hyper-Spectral Imaging by Neural Network for Blood Stain Characterization

3D Acoustic Mapping in Automotive Wind Tunnel: Algorithm and Problem Analysis on Simulated Data

Aeroacoustic source localization on open rotor aircraft model in wind tunnel tests