Development of a non-contact torque transducer based on the laser speckle contrast method

Abstract. When a torque measurement is required, torque transducers show many drawbacks during their use: the usual limits are the need for contact and the effects on shaft line parameters. A new approach is proposed in this work: a non-contact torque meter for a machine shaft has been developed. It carries out torque measurements evaluating the torsional displacement between two distinct sections of the shaft, through the monitoring of their roughness. The sensing principle employed is the classical laser speckle contrast method. The outcoming intensity scattered by the rough surface is processed by a cross-correlation function. In this way, the angular torsion of two distinct sections is obtained. It is therefore possible to point out the applied torque knowing the shaft torsional stiffness

diagnosis of vortex induced vibration of a gravity damper

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A new system for the measurement of gripping force based on scattering

The measurement of contact pressure of human fingers is very important to understand human perceptual mechanisms, that is the main goal of most of the neuroscientific studies. It may also lead to a correct development of tactile devices and haptic systems, as they are intended to convey controllable and effective stimuli.In this work, an optical measurement system based on Frustrated Total Internal Reflection (FTIR) is proposed for the measurement of the pressure distribution on the contact area between a human finger and a flat surface. The feasibility study performed shows that the tested sensor can be effectively used for the measurement of the fingertip contact pressure both on static and dynamic conditions.</span

How Wind Turbines Alignment to Wind Direction Affects Efficiency? A Case Study through SCADA Data Mining

SCADA control systems are the keystone for reliable performance optimization of wind farms. Processing into knowledge the amount of information they spread is a challenging task, involving engineering, physics, statistics and computer science skills. The present work deals with the effects on the efficiency of turbine inability of optimal aligning to the wind direction, due to meandering wind caused by wakes. The approach is tested on a judiciously chosen cluster of turbines of a wind farm sited in southern Italy. By a post-processing method based on discretization of nacelle position measurements, a set of dominant patterns of the cluster is identified. The patterns associated to best performances are individuated and it is shown that they correspond to non-trivial alignment to wind direction

On the Possible Wind Energy Contribution for Feeding a High Altitude Smart Mini Grid

The use of renewable energy sources to increase electricity access, especially in remote areas as high mountains, is a possible contribution to poverty reduction, climate change mitigation and improved resilience. In this paper an evaluation of the wind potential of a remote area in Nepal is performed, using CFD methods and the simulation of a micro wind turbine projected by Perugia University. With an accurate analysis of wind data and air density effects it is possible to test energy production potential in areas with high average wind speed. The overall estimated production for each turbine is an interesting result and an easily exportable contribution to the perspective of sustainable development at very high altitudes and remote areas

A new system for the measurement of gripping force based on scattering

The measurement of contact pressure of human fingers is very important to understand human perceptual mechanisms, that is the main goal of most of the neuroscientific studies. It may also lead to a correct development of tactile devices and haptic systems, as they are intended to convey controllable and effective stimuli.In this work, an optical measurement system based on Frustrated Total Internal Reflection (FTIR) is proposed for the measurement of the pressure distribution on the contact area between a human finger and a flat surface. The feasibility study performed shows that the tested sensor can be effectively used for the measurement of the fingertip contact pressure both on static and dynamic conditions.</span

Rivers' Water Level Assessment Using UAV Photogrammetry and RANSAC Method and the Analysis of Sensitivity to Uncertainty Sources

Water-level monitoring systems are fundamental for flood warnings, disaster risk assessment and the periodical analysis of the state of reservoirs. Many advantages can be obtained by performing such investigations without the need for field measurements. In this paper, a specific method for the evaluation of the water level was developed using photogrammetry that is derived from images that were recorded by unmanned aerial vehicles (UAVs). A dense point cloud was retrieved and the plane that better fits the river water surface was found by the use of the random sample consensus (RANSAC) method. A reference point of a known altitude within the image was then exploited in order to compute the distance between it and the fitted plane, in order to monitor the altitude of the free surface of the river. This paper further aims to perform a critical analysis of the sensitivity of these photogrammetric techniques for river water level determination, starting from the effects that are highlighted by the state of the art, such as random noise that is related to the image data quality, reflections and process parameters. In this work, the influences of the plane depth and number of iterations have been investigated, showing that in correspondence to the optimal plane depth (0.5 m) the error is not affected by the number of iterations

A Procedure to Perform Multi-Objective Optimization for Sustainable Design of Buildings

When dealing with sustainable design concepts in new construction or in retrofitting existing buildings, it is useful to define both economic and environmental performance indicators, in order to select the optimal technical solutions. In most of the cases, the definition of the optimal strategy is not trivial because it is necessary to solve a multi-objective problem with a high number of the variables subjected to nonlinear constraints. In this study, a powerful multi-objective optimization genetic algorithm, NSGAII (Non-dominated Sorting Genetic Algorithm-II), is used to derive the Pareto optimal solutions, which can illustrate the whole trade-off relationship between objectives. A method is then proposed, to introduce uncertainty evaluation in the optimization procedure. A new university building is taken as a case study to demonstrate how each step of the optimization process should be performed. The results achieved turn out to be reliable and show the suitableness of this procedure to define both economic and environmental performance indicators. Similar analysis on a set of buildings representatives of a specific region might be used to assist local/national administrations in the definition of appropriate legal limits that will permit a strategic optimized extension of renewable energy production. Finally, the proposed approach could be applied to similar optimization models for the optimal planning of sustainable buildings, in order to define the best solutions among non-optimal ones

Comparison between Finite Elements simulation of residual stress and Computer Vision measurements in a welding TIG process

In this work, residual stresses arising after an industrial TIG welding process on an aerospace grade part are investigated. The customer demand for high product resistance and high dimensional accuracy calls for the control of the welding process and the minimisation of the residual stresses. Dimensional check of manufactured parts was traditionally performed in a quality room by means of coordinate measuring machines (CMM). For parts larger than 1 meter, this operation shows several issues, as the handling and the need for large and expensive measuring devices. These needs can be fulfilled by an innovative method that, through continuous dimensional check, allows to optimise the welding process parameters. This method is built on a post-process measurement of part shrinkage based on a Computer Vision technique, the outcome being a 3D reconstruction of the actual part. Moreover, the whole procedure is low-cost and time saving, as it can be performed with a conventional camera mounted on a tripod. A Finite Element Model (FEM) of the TIG process on the selected sample was developed. The result of the numerical model was compared with the Computer Vision-based post-process measurement. The simulation scenario predicted by Finite Element Analysis agrees with measurements