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Page 798 of 977 Results 7971 - 7980 of 9762

L. Cocco, P.Gazzola, S.Rapuano, L. Rossi
VIBRATIONS MEASUREMENTS OF FORMULA ONE CAR ELECTRONIC DEVICES

F1 car is a very critical system in terms of temperature, shock and vibrations. For this reason, usually, automotive standards are no adequate for motor-sport electronic applications. Further peculiarity of F1 automobiles is the periodic change of vehicle dynamic setting. Vibration monitoring techniques are being used by F1 teams mainly to spot mechanical imbalances and, consequently, to define a car’s set up. In the competitive race context, also it is mandatory to improve the electronic components reliability, to optimize their maintenance time, to control the quality of their manufacturing and to take into account their noise and vibration pollution. This paper presents an experimental vibration measurement system implemented on Ferrari racing car model 248F1.

Luca De Vito, Sergio Rapuano, Maurizio Villanacci
AN AUTOMATIC DSP-BASED CLASSIFIER FOR IMPAIRMENTS ON QAM MODULATIONS

This paper presents an instrument for the automatic classification of the common impairments on Quadrature Amplitude Modulation (QAM) signals. The instrument is intended to help telecommunication service providers to guarantee Quality of Service (QoS) to their customers. Starting from an already developed method based on the processing of the constellation diagram image, the paper presents both significant improvements in the method and the realization of a prototype of impairment classifier, based on a multi-DSP hardware architecture. Experimental results of the validation phase of the realized instrument are presented, too.

Pier Andrea Traverso, Gaetano Pasini, Antonio Raffo, Domenico Mirri
THE DTCM CHARACTERIZATION APPROACH FOR THE QUALIFICATION OF DYNAMIC NON-LINEARITIES WITHIN A/D CHANNELS

The behaviour of both stand-alone ADCs and entire A/D acquisition channels under time-varying input excitations exhibits non-idealities which are peculiar to the dynamic operation and can not be described by the characteristics of the static response. In addition, even the common dynamic parameters suggested by the current standards usually fail to separately qualify the purely-dynamic non-linearities from all other perturbation effects on the system response. In this paper, the features of the Discrete-Time Convolution Model are discussed by pointing out the properties of the general approach from which it derives, with particular emphasis to the capability of separately describing all the system non-idealities on the basis of their nature. It will be shown how the DTCM characterization methodology and the set of related model parameters represent a suitable resource towards the separate qualification of dynamic non-linearities in A/D channels.

Carlo Michelassi, Giacomo Monaci
AVAILABILITY ASSESSMENT OF A RAW GAS RE-INJECTION PLANT FOR THE PRODUCTION OF OIL AND GAS

Driven by the needs of highly competitive markets, the performance requirements of today’s production systems are becoming increasingly demanding. High availability is one of the key requirements for new machines and industrial plants. The objective of the present study is the assessment of the availability of a Gas Re-injection Plant used for the production of oil and gas in the Kashagan field (Kazakhstan). In order to assess the availability performance of this complex system, a broad set of studies has been carried out to gather accurate information at the level of detail considered suitable to meet the availability analysis target. Following this preliminary work, the availability analysis was performed using a simulation approach. The RBD (Reliability Block Diagram) technique, in conjunction with Monte Carlo simulations, allowed many different elements to be evaluated simultaneously to determine the plant availability.

S. Nuccio, C. Spataro, G. Tinè
EFFECTS OF THE ELECTROMAGNETICAL DISTURBANCES IN THE DAQ-BASED MEASUREMENT INSTRUMENTS AND THEIR COMPENSATION

In previous works, we analysed the behaviour of data acquisition board based measurement instruments when they are subjected to the electromagnetic disturbances prescribed in the IEC-61326 Standard. The study has shown that the effects of both radiated and conducted emissions alter the performances of this instrumentation when not-shielded configurations are used; in fact, in these cases, the parameters which characterise a data acquisition board can reveal an appreciable degradation. On the contrary, even the heaviest disturbances cause a negligible impact if the good practices of shielding are observed. Since the full-shielded configurations are quite expensive, it would be useful to find a way to safely employ also a not-shielded configuration in the hostile electromagnetic environments. With this aim, in the paper, we propose two methods for the compensation of the electromagnetic disturbances impact. The first one is a software approach, applicable in cases of steady disturbances. The second approach is based on a two channels acquisition technique applicable with boards which can simultaneously acquire two signals. The practical application of both methods has produced satisfactory results.

S. Nuccio, C. Spataro
FIGURES OF MERIT FOR ANALOG-TO DIGITAL CONVERTERS: THE OPTIMAL SET FOR THE UNCERTAINTY EVALUATION

Choosing the right analog-to-digital converter for a stated measurement application and for a stated target uncertainty is not an easy task. In fact, each time the prospective purchaser browses among the manufacturer specifications, he finds different sets of parameters which qualify the product; moreover, the same figure of merit is often defined and measured in ambiguous way. One of the main reasons which has caused this situation is the coexistent of various Standards concerning the characterization of the analog-to-digital converters. The choice of the converter becomes more difficult taking into account that the potential buyer has to deal with the measurement uncertainty. Without question, the homogeneity of the figures of merit would facilitate the measurement evaluation. Target of the paper is the choice, among the large number of parameters proposed by the various Standards, of the optimal set of merit figures, which allows a correct uncertainty evaluation of a generic measurement performed by using an analog-to-digital converter. This want be a contribution toward the long awaited harmonization of the aforesaid Standards.

Drago Cmuk, Tarik Mutapcic, Mladen Borsic
MOBILE MEASUREMENT SUPPORT FOR REMOTE LABORATORIES AND E-LEARNING SYSTEMS

Practical work in the laboratory using real instruments is a strong emphasis for theoretical knowledge but also a powerful drawback for distance learning in universities. The paper describes development of a remote laboratory for mobile devices. Given the detailed analysis of potential benefits coming from the deployment of such a system, the author analyzed the technologies suitable for its realization. Multi-tier platform has been developed to support Mobile learning and experimentation. For visualization and control of experiments a thin-client paradigm based on DHTML has been developed. It allows users to visualize and control experiments remotely on handheld devices, using mobile browser only. Application tier is based on deployment of ProperJavaRDP client with custom web server written in Java. Experiment tier runs experiment written in whichever language, thus enabling high reusability of the system. Data tier is based on deployment of customized Moodle LMS with layout adapted to fit the screen and other limitations of handheld devices. It takes care of user authentication and opening session towards Mobile Laboratory Server. This Mobile learning system can enhance user learning process by providing support for discursive learning approach according to the behavioral, cognitive and constructivist theories of learning.

Doris Bao, Luca De Vito, Sergio Rapuano
SELECTING TEST SIGNALS FOR SUCCESSFUL IMPAIRMENT CLASSIFICATION IN VOIP SYSTEMS

The paper proposes a metrological analysis for selecting the test signals to be used with a method for the automatic classification of impairments in VoIP telecommunication systems. The method is able to identify the VoIP network impairments which decrease voice quality, by analyzing the power of a test signal during the call. Test signals, considered in this work, comprise speech-like signals, non- speech-like deterministic signals and non- speech-like stochastic signals, taken either from standard specifications or from literature papers on voice quality assessment. In order to evaluate the optimal test signals, two network emulators have been used to add the impairments in a controlled test network. The selected test signals improve significantly the method performance in terms of classification success rate and test duration.

Marek Niedostatkiewicz, Grzegorz Lentka
TEST FREQUENCIES SELECTION CRITERIA FOR PARAMETER IDENTIFICATION OF ANTICORROSION COATING USING BILINEAR TRANSFORMATION

The electrical modelling of technical and biological objects has become very popular, as it allows diagnosis of their state with tools and methods designed for electrical circuits. To identify equivalent circuit parameters, usually conventional impedance spectroscopy methods are used, despite their drawbacks – long measurement time and high numerical complexity. An alternative identification method is based on the bilinear transformation of impedance function. Not only it accelerates the measurement, but also it simplifies the calculations, as the relations between measured impedance and parameters are analytical. However, the method requires a precise selection of impedance measurement frequencies. In the paper, we briefly present the bilinear identification method and compare some new frequencies selection criteria based on the length of bilinear transform identification curve on complex plane, representing the high-signal sensitivity of impedance function to model parameters. The criteria are compared in terms of identification error of parameters. As a test object the Beaunier’s model of the anticorrosion coating in its early stage of degradation has been chosen.

M. Ceccarelli, D. Grimaldi, F. Lamonaca, A. Speranza
A COMPUTER VISION APPROACH TO MICRO-NUCLEUS AUTOMATIC DETECTION AND SURFACE MEASUREMENTS

This paper reports a novel method for Nucleus and Micro Nucleuses segmentation. These biological structures are very handy to biologists for relieving structural chromosome aberration. The adopted method consists into a pipeline of advanced computer vision algorithms same of them specifically tailored for the current segmentation problem. Starting from the knowledge of approximate size and shape of Micro Nucleuses it is possible to efficiently segment all the image features by computer vision approach.

Page 798 of 977 Results 7971 - 7980 of 9762