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Franco Pavese
ANALYSIS OF CONSISTENCY OF THE BASIC CONCEPTS FOR THE EXPRESSION OF UNCERTAINTY IN THE PRESENT INTERNATIONAL WRITTEN STANDARDS AND GUIDES

At present, several international written standards and guides are available, dealing with the expression of uncertainty in measurement, calibration and testing, and concerning the definition of the basic concepts and related nomenclature and basic methods for data analysis. An inspection and comparison of these texts, which were prepared in a time span of more than twenty years, shows that, to different degrees, not all of them are consistent with each other, probably due mainly to an advancement of the discussion and of agreed solutions that took place in the indicated time span and that can be observed for most of them. The paper addresses an attempt to identify what appears as more or less serious inconsistencies that in author’s view should be removed in the process of revision, already started for several of them, and that may communicate a sense of confusion especially at the floor-user level.

E. Balestrieri, P. Daponte, S. Rapuano
PRELIMINARY REPORT ON ADC CHARACTERIZATION IN THE FREQUENCY DOMAIN IN THE INTERNATIONAL STANDARDS

The paper reports the latest results of the authors’ work within the project “Development of new methods for the characterization, modelling and correction of A/D and D/A conversion non-ideality, to contribute to the harmonization and the upgrade of the relative international standards”, co-funded by Italian Ministry of Education, University and Research. In particular, an experimental investigation for the harmonization of the measures of the ADC dynamic performance in the frequency domain, according to the standards in the field, is described. The comparison results show a good degree of similitude among the results provided using procedures and formulas from different standards of IEEE and IEC.

Lorenzo Ciani, Marcantonio Catelani, Mario Mancini, Enrico Simoni
A NEW METHOD OF FEEDBACK CONTROL FOR POWER INVERTER BASED ON A SINGLE VOLTAGE SENSOR

The main objective of static power inverters is to produce an AC output waveform from a DC power supply. These are the types of waveforms required in adjustable speed drives (ASDs), uninterruptible power supplies (UPS), static VAR compensators (SVC), active filters, flexible AC transmission systems, and voltage compensators, which are only a few of the possible applications. For sinusoidal AC outputs, the magnitude, frequency, and phase should be controllable. The purpose of this research, in collaboration with Astrid Energy Enterprises, is to design and realize an innovative method of feedback control for inverter systems based on a single voltage sensor. This paper gives a detailed description of the system carried out and its potentiality as compared to the state of the art.

Marcantonio Catelani, Valeria L. Scarano, Roberto Singuaroli, Francesco Bertocci, Paolo Palchetti
ROHS REQUIREMENTS FOR ELECTRONIC APPLICATIONS: MEASUREMENTS OF CHARACTERISTICS OF SILVER EPOXY ADHESIVES SOLDER JOINTS

It is emerged the necessity to modify the soldering process of all the devices under the RoHS European Directive, in order to eliminate the presence of lead. So our research is oriented to study the use of new materials for connections in electronic devices and to measure their characteristics and reliability performances. In this paper it is shown the preliminary characterization of a new study of the use of conductive materials without lead for the adhesion of the plate, which has piezoelectric properties, with the fingers’ comb. Found a possible variability of the samples production process, it appeared opportune to apply a Design of Experiments method (D.o.E.), to understand the degrees of correlation between the interested variables. After having chosen the output control characteristics of the process, (measures of electrical resistance of every single element of transducer’s array) the variables, which are potentially responsible of the uncertainty on the aforesaid measures, have been characterized. The samples and the measurement system are implemented and the results are discussed in this paper.

Lorenzo Ciani, Marcantonio Catelani, Lorenzo Veltroni
FAULT TOLERANT TECHNIQUES TO DIAGNOSE AND MITIGATE SINGLE EVENT UPSET (SEU) EFFECTS ON ELECTRONIC PROGRAMMABLE DEVICES

This research faces the problem of disturbance induced by high energy particles on electronic devices. Based on detailed analysis of this phenomenon, the work is divided into two parts: in the first part testing of the Single Event Upset (SEU) has been carried out with the aim of determining diagnostic techniques and the mitigation of this disturbance, taking into account the fact that testing is one of the fundamental points in electronic programmable devices; in the second part a fault tolerant technique has been devised so as to achieve the requirements demanded on a real avionic system.

Marcantonio Catelani, Valeria L. Scarano, Roberto Singuaroli,Stelio Montebugnoli, Germano Bianchi, Federico Perini
NORTHERN CROSS RADIORECEIVER CHAINS: THE ENVIRONMENTAL TEST ON THE CRITICAL SUBSYSTEM

This research is developed in collaboration with the Istituto di Radioastronomia, Istituto Nazionale di Astrofisica (IRA-INAF) located at Medicina (Bologna), in the context of the BEST (Basic Element for SKA Training) project. SKA is the name given to a new generation radio-telescope that will have 1 km² of effective collecting area. SKA will be the most sensitive radio-telescope ever built that allows a deeper knowledge of the universe. After a reliability analysis we estimated the MTBF of the two approaches so we suggested the most reliable solution to implement. This work considers the most reliable solution for the radio astronomical signal receiver chains, the solution that conveys the analog signal through optical fibre. Since the reliability prediction indicated the front-end, installed on the focal line of the antenna, as the more stressed block by environmental and climatic factors, we recommended to perform the environmental tests on it. The results of the random vibration test and the water and shock test planning are presented in this paper.

Marcantonio Catelani, Lorenzo Ciani, Valeria L. Scarano, Alessandro Bacioccola
AN AUTOMATIC TEST FOR THE SOFTWARE RELIABILITY: THE EVALUATION OF THE OVERFLOW DUE TO MEMORY LEAKS AS FAILURE CAUSE

In order to guarantee a software with high quality level vs a reasonable cost, the testing planning phase has to be study in detail, also to reduce the test time. This paper introduces the result of the application of software automatic test to one of the most common software failure causes: the overflow due to memory leaks. The analysis carried out on a single software failure cause wants to show the total generality of the technique and to define some parameters of life of the software. The general value of the method is shown applying the technique to different software and for everyone of them defining the mean time to failure, where with failure we mean only the failure due to overflow; even if the overflow it isn’t the only analyzable failure cause through the application of such software automatic test.

AA. VV.
DEVELOPMENT OF INNOVATIVE METHODS FOR CHARACTERIZING, MODELING AND CORRECTING THE NON-IDEAL BEHAVIOR OF A/D AND D/A CONVERSION CHANNELS, IN ORDER TO CONTRIBUTE TOWARDS HARMONIZING AND UPGRADING INTERN

The research program aims at improving the performance of appliances based on Analog-to-Digital and Digital-to-Analog conversion (ranging from measuring instruments to on-chip ADC and DAC). This will be done by developing methods for the accurate measurement and correction of conversion errors (including, when applicable, errors caused by transducers and signal-conditioning blocks). Another aim of the research is to expand the scope of the theory of measurement uncertainty, including conversion errors in dynamic conditions. This will allow the manufacturers to qualify correctly the non-ideality of a conversion channel in the specifications, and the users to use correctly the given figures to compute the uncertainty introduced by the conversion. The research, developed for the parts of competence by the five coordinated Units, aims also at contributing in real terms towards the improvement and the harmonization of the existing standards, which currently present various discrepancy and obvious deficiencies with respect to the state of the art.

M. Catelani, A. Zanobini, L. Ciani
WORD ERROR RATE MEASUREMENT IN ANALOG-TO-DIGITAL CONVERTERS: SOME STATISTICAL CONSIDERATIONS ABOUT IEEE STD 1241-2000, ANNEX A

The word error rate (WER) in an Analog to Digital Converter (ADC) is the probability of receiving an erroneous code for an input, after correction is made for gain, offset, and linearity errors, and a specified allowance is made for noise. Typical causes of word errors are metastability and timing jitter of comparators within the ADC. The aim of this paper is to give a contribution for a new draft of the IEEE Std 1241. Our attention is directed towards the word error rate estimation and to the Annex A of this standard. New statistical techniques which can better integrate what is sustained in the IEEE standard and have been proposed. In particular, Student and chi-square distributions have been introduced for a more accurate measurement of the word error rate in the case of n successive observations.

L. Cocco, P.Gazzola, S.Rapuano, L. Rossi
ASSESSMENT OF VIBRATION SUSCEPTIBILITY OF ELECTRONIC EQUIPMENT IN FORMULA ONE CARS

The total noise level in racing car environment is very high, in fact the engine can reach 20000 rpm (revolutions per minute) and the vehicle structure is very stiff. Upper-grade levels in terms of shock, vibration and temperatures need a careful understanding of damage mechanism, which will be active in this environment. This paper presents an experimental vibration diagnostic methodology implemented on Ferrari racing car model 248F1.

Page 797 of 977 Results 7961 - 7970 of 9762