IMEKO Event Proceedings Search

   

Page 293 of 977 Results 2921 - 2930 of 9762

Daniel Belega, Dario Petri, Dominique Dallet
Accurate Amplitude Estimation of a Noisy Sine-wave via Interpolated DFT Algorithm

This paper analyses Mean Square Error (MSE) of a noisy sine-wave amplitude estimator based on the Discrete-Time Fourier Transform (DTFT) evaluated at the signal frequency estimated by the classical Interpolated Discrete Fourier Transform (IpDFT) algorithm. In order to reduce the contribution of the spectral image component on the returned estimates, the sine-wave is weighted by a Maximum Sidelobe Decay (MSD) window. An analytical expression for the estimator MSE is derived. For given Signal-to-Noise Ratio (SNR) and number of processed samples, that expression allows us to derive the minimum number of acquired sinewave cycles ensuring that the detrimental contribution of the image component on the estimation accuracy is negligible as compared with the effect of wideband noise. In such condition, both computer simulations and experimental results show that the analysed DTFT-based estimator outperforms the classical DFT-based estimator.

R. Gassino, G. Perrone, A. Vallan
Experimental Qualification of Fiber Bragg Grating Sensors for Temperature Monitoring in Laser Ablation

The paper discusses the main issues related to the usage of Fiber Bragg Gratings as temperature sensors when they are employed to monitor percutaneous laser ablation of tumors. After a description of the main problems related to this specific application, two different setups for the characterization and the qualification of these sensors are described and preliminary results are presented.

Vítor Viegas, J. M. Dias Pereira, Octavian Postolache, Pedro Silva Girão
Application of Force and Inertial Sensors to Monitor the Usage of Walker Assistive Devices

Walker assistive devices should be used properly in order to provide maximum safety and comfort to the user. We define two risk indexes to monitor walker usage, one related with force unbalance, and the other related with motor incoordination. We present a measurement system capable of measuring these two indexes and prevent potential risk situations. Force unbalance is measured using load cells attached to the walker legs. Motor incoordination is estimated by synchronizing force measurements with kinematic data provided by an Inertial Measurement Unit (IMU). The measurement system is equipped with a Bluetooth link that enables local supervision on a computer or smartphone. Calibration and experimental results are included in the paper.

Bogdan C. Neagu, Gheorghe Grigoraș
Detection of Irregular Consumption to Load Monitoring in Smart Grids Environment

Today, power distribution operators are concerned about irregular behavior of electricity consumption in their decision-making process. In the load data, abnormal consumptions may happen due to measurement error, undetected consumption, illegal electricity connection, improperly installed equipment etc. The paper presents a statistical approach which acquires the basic concept of knowledge discovery on databases (KDD)with data mining, focuses on the identification of outliers (irregular consumption) from load curves recorded by Smart Meters on the substation of the power distribution networks. In order to validate the proposed approach, a real database with 300 substations from rural area was used. The results demonstrate that by detection and elimination of irregular consumption, the load curves can be efficiently used by modern distribution operators for a better operation and planning of actually “smart” networks.

Andrea Rossi, Francesco Orsini, Andrea Scorza, Fabio Botta, Fabio Leccese, Enrico Silva, Kostiantyn Torokhtii, Ivan Bernabucci, Salvatore Andrea Sciuto
A preliminary performance validation of a MEMS accelerometer for blade vibration monitoring

Nowadays a large number of studies are being carried out on active vibration control, especially in the aeronautical gas turbine industry. Indeed, uncontrolled vibration in aeronautical engine blades can lead to fatigue failure with catastrophic consequences. For this reason, many efforts are made to implement an embedded active vibration control on rotors. Furthermore in this particular kind of application a compact, integrated and robust system, controlled by a wireless remote system, is necessary. Before designing the vibration active control it is mandatory to characterize the vibration monitoring system of the blade in order to develop a feedback system for active damping. To this regard a MEMS accelerometer for mobile applications (MEMSWMAA) may be considered a good choice, since the wireless features are relevant in a rotor vibration monitoring application, its cost is usually low and its size and weight allow to obtain a lower insertion effect. However, the metrological limits of this type of sensors are not well investigated. In this work a preliminary characterization of a MEMSWMAA for blade vibration monitoring application is proposed. In particular the authors evaluate the actual performance of MEMSWMAA by means of a direct and simultaneous comparison with a reference sensor. The frequency range of investigation (10 Hz up to 1080 Hz) includes the first three resonant frequencies of a cantilever beam that will be used in a future work to experimentally validate the vibration control algorithm.

Andrea Scorza, Daniele Pietrobon, Francesco Orsini, Salvatore Andrea Sciuto
A Preliminary Study on a Novel Phantom Based Method for Performance Evaluation of Clinical Colour Doppler Systems

Ultrasound Colour Flow is an imaging technique that combines velocity with anatomical information obtained by means of ultrasonic Doppler techniques and pulse-echo methods respectively to generate colour coded maps of the blood flow velocity superimposed on grey-level images of the tissue anatomy. Ultrasound Colour Flow Imaging (CFI) has been found to be effective in assessing blood flow in many clinical conditions and its use is widespread in many diagnostic applications. Although this technique for obtaining the blood velocity information is technically demanding and requires specific tests for its assessment, a shared worldwide standard on CFI equipment testing is not published yet and in the scientific literature there is no agreement on the choice of parameters to be tested, measurements methods and the timing of the test. After a brief introduction to the main principles and main methods in the scientific literature for quality assessment of CFI systems, a novel phantom based method is proposed and applied for a quantitative analysis of the performances of a commercial ultrasound scanner. Finally first results are shown and commented.

L. Schinaia, A. Scorza , F. Orsini,S. A. Sciuto
Feature Classification in Ultrasound Textures for Image Quality Assessment:a Preliminary Study on the Characterization and Selection of Haralick Parameters by Means of Correlation Matrices

This paper describes a preliminary study on feature selection from the gray level co-occurrence matrix (GLCM) among the 14 features proposed by R.M. Haralick (1979) with the aim to apply them to ultrasound image classification and Quality Assessment. In particular4 main-classes of images with different patterns (Lines, Chess, alternates Row and Circles)have been implemented and different levels ofspeckle noisehave been added to simulate ultrasound images with different textures.With the aim to characterize therelationship betweenHaralickfeatures and the pattern type, size, contrastand noise, someCorrelation Matrices have been implemented. Preliminary results are explained and discussed.

L. Schinaia, A. Scorz, F. Orsini, S. A. Sciuto
Ultrasound image Uniformity Assessment by Means of Sparse Matrices: Algorithm Implementation and First Results

The current study is focused on an image segmentation algorithm for Uniformity Quality assessment in Diagnostic Ultrasounds.In particular a mathematical definition of the uniformity in ultrasound images is introducedand a split and merge algorithm performed on sparse matricesto measure uniformity is described. The algorithm is based on the Gray-Level Co-occurrence Matrices and the relativedescriptors,i.e. the Haralick features Entropy, Energy, Maximal CorrelationCoefficientand InformationMeasures of Correlation.Results on2 differentdatasetsof test images with different nonuniformities have been carried on. Several outcomesshow a goodsensitivity and agreement with the mean judgment by 7 human observers, i.e. differences are below 40% in most of the cases.On the basis of previousstudies, the latest developments and results are proposed and commented.

A. Rossi, F. Orsini, F. Botta, A. Scorza, L. Schinaia, D. Bibbo, S. A. Sciuto
A Novel Method for Whole Body Vibration Platform Characterization for Clinical Applications

In the last decades, many studies have been conducted on the biological effects resulting from Whole-Body Vibration (WBV) platforms, even if benefits or side effects resulting from exposure to whole-body vibrations in sport and rehabilitation applications are often conflicting. These discrepancies are likely due also to different operating conditions such as load, unload, load position on footboard, etc. Since acceleration differences could affect the biological response of the person it would be suitable to verify the actual vibrations. Nevertheless a standard and widespread accepted method for measuring and verifying the actual vibrations provided by a WBV device has not been established yet. The authors performed a characterization of a novel WBV platform by developing a method reported in section II. The tests carried out in different conditions show that the footboard doesn’t provide quite uniform vibrations along the vertical direction over the platform. Furthermore, transversal accelerations have been detected and in some cases they reached the 25% of the vertical ones. Currently, very few studies have investigated whether a WBV platform produces comparable accelerations in at least two points of the footboard. This paper proposes a method for the characterization of WBV platforms and the comparison of their performances.

Francesco Orsini, Andrea Rossi, Andrea Scorza, Fabio Botta, Salvatore Andrea Sciuto
A comparison between a commercial WBV platform and an experimental prototype

There are many commercial WBV platforms for clinical applications but in literature very few have been tested to verify their actual amplitude, frequency spectra and waveform shape of vibration, although some clinical studies showed that these parameters can influence significantly the muscles performance. In this study the performances of a prototype WBV1 designed by the authors are compared with a commercial platform WBV2 typically used in clinical and rehabilitation investigations. Tests performed with four accelerometers in 3 different directions show the presence of transversal accelerations that in some cases exceeded the vertical one in WBV2 while they were always lower than the 25% in WBV1. Also the waveform shape of the vibration provided by WBV1 , evaluated by means of the SINAD parameter, show a better value compared to the commercial device: indeed secondary harmonics reaches the 30% of the fundamental in WBV2 but they are always below the 25% in the prototype.

Page 293 of 977 Results 2921 - 2930 of 9762