Search results for "Ultrasonic"
showing 10 items of 565 documents
PAUT inspection of complex-shaped composite materials through six DOFs robotic manipulators
2015
The requirement to increase inspection speeds for the non-destructive testing (NDT) of composite aerospace parts is common to many manufacturers. The prevalence of complex curved surfaces in the industry provides significant motivation for the use of six-axis robots for the deployment of NDT probes in these inspections. The IntACom project, developed by TWI Technology Centre (Wales) and supported by a number of major aerospace partners and the Welsh government, has produced a prototype robotic NDT system. The prototype system is capable of inspecting complex-geometry composite components with great time savings. Two six-axis robotic arms deploy end effectors carrying phased array ultrasonic…
Fuzzy Data Fusion for Real-World Mapping Using 360° Rotating Ultrasonic Sensor
1997
Abstract Mobile robot perception of the external environment is limited by the features of the used sensor. An useful technique used to improve robot perception is data fusion. This paper presents an approach to build a map of an unknown environment applying fuzzy data fusion methods to data acquired through an ultrasonic sensor. Conditioning of these data and motion control of the mobil robot by fuzzy data fusion are also described. The resulting two dimensional map is used for path planning and navigation. The proposed approach is exrperimentally tested using real distance measures acquired by a 360° rotating sensor.
Identification of the inertial model for innovative semi-immergible USV (SI-USV) drone for marine and lakes operations
2015
The proposed project shows the results obtained in the implementation and testing in lacustrine and marine environment of a nautical remote controlled vehicle with surface navigation and innovative features Semi-Immergible (SI-USV). This vehicle is based on a pending patent belonging to Palermo University (Patent Pending RM2012A000209 and Patent RM2014Z000060) concerning innovative semi-immersible vehicles (SI-Drone), that can be remotely controlled from the ground, air, satellite and sea also during the semi-immersible operation. Given its low draft, the electric powered vehicle, coupled with jet propulsion, makes it possible to navigate in shallow waters, coastal shipping or sandbars.
Problems in determining the size of the population and critical groups exposed to environmental noise
1978
Abstract In order to better estimate how and to what extent people are affected by exposure to environmental noise, an attempt must be made to calculate first the size of the entire population exposed to certain levels of noise and, second, groups within the population which are particularly sensitive to noise. Such a study has been started in the Federal Republic of Germany. It has been estimated that about 14 million people are exposed to sound levels of roughly 62 dB(A) and about 2 million to levels of roughly 70 dB(A). Nothing is yet known about the existence or size of sensitive groups within these populations, however, and the following report lists areas needing research in terms of …
Stability criteria, atomization and non-thermal processes in liquids
2008
Analyzing the first equation in the BBGKY chain of equations for an equilibrium liquid-gas system, we derived the analytical expression for the atom work function from liquid into gas. The coupling between the atom work function from liquid into vacuum and the stability criterion of liquid in limiting points of the first type was shown (using I.Z.. Fisher classification). As it turned out, Fisher's criterion corresponds to the condition of atomization. We have expressed the state equation in terms of the atom work function from liquid into vacuum and performed calculations of the limiting line of stability composed of limiting points of the first type for argon. Our model discovers an inter…
Inclusion ratio based estimator for the mean length of the boolean line segment model with an application to nanocrystalline cellulose
2014
A novel estimator for estimating the mean length of fibres is proposed for censored data observed in square shaped windows. Instead of observing the fibre lengths, we observe the ratio between the intensity estimates of minus-sampling and plus-sampling. It is well-known that both intensity estimators are biased. In the current work, we derive the ratio of these biases as a function of the mean length assuming a Boolean line segment model with exponentially distributed lengths and uniformly distributed directions. Having the observed ratio of the intensity estimators, the inverse of the derived function is suggested as a new estimator for the mean length. For this estimator, an approximation…
Inspection of additive-manufactured layered components
2015
Laser powder deposition (LPD) is a rapid additive manufacturing process to produce, layer upon layer, 3D geometries or to repair high-value components. Currently there is no nondestructive technique that can guarantee absence of flaws in LPD products during manufacturing. In this paper a laser ultrasonic technique for in-line inspection of LPD components is proposed. Reference samples were manufactured from Inconel and machined flaws were created to establish the sensitivity of the technique. Numerical models of laser-generated ultrasonic waves have been created to gain a deeper understanding of physics, to optimize the set-up and to verify the experimental measurements. Results obtained on…
FEM and experimental analysis of a total knee prosthesis
2018
In this study, a comparison between two different approaches used to study a total knee prosthesis is presented. In particular, the contact area of the components of knee prosthesis has been evaluated using both a numerical and an experimental approach. The numerical analysis has been performed by FEM Models, whereas the experimental study has been conducted using an ultrasonic-based method. To setup the FEM simulations, CAD Models of the components of the prosthesis have been reconstructed using a classic reverse engineering approach. Obtained results has allowed evaluating the contact area of the components of the prosthesis and demonstrated a very good level of correlation between numeri…
Bifurcation analysis of a TaO memristor model
2019
This paper presents a study of bifurcation in the time-averaged dynamics of TaO memristors driven by narrow pulses of alternating polarities. The analysis, based on a physics-inspired model, focuses on the stable fixed points and on how these are affected by the pulse parameters. Our main finding is the identification of a driving regime when two stable fixed points exist simultaneously. To the best of our knowledge, such bistability is identified in a single memristor for the first time. This result can be readily tested experimentally, and is expected to be useful in future memristor circuit designs.
Adaptive Distance-Based Pooling in Convolutional Neural Networks for Audio Event Classification
2020
In the last years, deep convolutional neural networks have become a standard for the development of state-of-the-art audio classification systems, taking the lead over traditional approaches based on feature engineering. While they are capable of achieving human performance under certain scenarios, it has been shown that their accuracy is severely degraded when the systems are tested over noisy or weakly segmented events. Although better generalization could be obtained by increasing the size of the training dataset, e.g. by applying data augmentation techniques, this also leads to longer and more complex training procedures. In this article, we propose a new type of pooling layer aimed at …