IMEKO Event Proceedings Search

   

Page 852 of 912 Results 8511 - 8520 of 9113

Marinel Temneanu, Romeo Ciobanu, Cristian Fosalau, Mihai Cretu
MAGNETIC AMORPHOUS NANO-STRUCTURED WIRES CHARACTERISATION USING IMPEDANCE SPECTROSCOPY

In this article, we apply impedance spectroscopy methodology to analyze the frequency response of as cast CoFeBSi wires in the 100 Hz to 300 kHz frequency range, at 10 mA ac current. Comparative evaluation performed for stressed and unstressed samples reveals major changes in the spectra of internal ac impedance of the wire. Physical concepts and problems of practical significance are discussed on the basis of the results.

Tomasz Adamski
GENERALIZED NONSUBTRACTIVE DITHERING IN A/D CONVERSION – THEORY AND SIMULATION RESULTS

The paper deals with mathematical fundamentals of the generalized nonsubtractive dithering method (which can be used in A/D converters and sampling systems with repetitive sampling). The new concept is based on inverting a "dithering characteristic" F defined in the paper for arbitrary (but fixed) quantization functions. Errors of the method are assessed and analyzed in detail.

Marek Zielinski, Marcin Kowalski, Dariusz Chaberski, Slawomir Grzelak
ESTIMATION OF THE CLOCK SIGNAL JITTER USING THE TIME-INTERVAL MEASUREMENT SYSTEM

Accumulated clock signal jitter is a significant source of errors in many measurement systems. In this paper a new method of estimation of clock signal jitter will be discussed. This method enables to calculate an accumulated jitter and time-interval error [TIE] as a function of the clock cycles. The time-interval measurement system [TIMS], accommodated for jitter measurements and their application for estimations of jitter parameters will be also presented and discussed.

Roman Kaszynski, Jacek Piskorowski
TIME-VARYING BUTTERWORTH FILTERS WITH COMPENSATED GROUP DELAY

This paper presents the concept of time-varying Butterworth filters with linear phase response. The compensation of the phase characteristics is carried out with the aid of the phase shifter system. The paper shows that it is possible to shorten the transient state in low-pass phasecompensated analog filters by varying in time selected parameters. This paper contains simulation results of the proposed filters and comparison with the classic circuits.

Pasquale Arpaia, Carmine Romanucci, Antonio Zanesco
PERFORMANCE ANALYSIS OF CULTURALLY OPTIMIZED WAVELET LIFTING SCHEME IN CORROSION DATA FILTERING

The optimal design of an adaptive wavelet filter based on lifting scheme by means of evolutionary cultural algorithms is proposed, with the aim of filtering data for dynamic corrosion monitoring. First, in corrosion rate measurement through electrochemical impedance spectroscopy, the problem of uncertainty due to noise arising from underground disturbances in buried structures is stated. Then, the proposed adaptive filtering procedure is illustrated. Finally, the results of the experimental validation on two different corrosion case studies are highlighted.

Fernando M. Janeiro, Pedro M. Ramos, Mouhaydine Tlemcani, A. Cruz Serra
ANALYSIS OF A NON-ITERATIVE ALGORITHM FOR THE AMPLITUDE AND PHASE DIFFERENCE ESTIMATION OF TWO ACQUIRED SINEWAVES

In this paper, a non-iterative algorithm for amplitude and phase difference estimation of two acquired sinewaves is presented and analyzed. The method is based on the least-squares fitting of ellipses where the common signal frequency is eliminated from the algorithm. requires the strict definition of the convergence criteria to stop the iterative method.

Carine Neus, Patrick Boets, Leo Van Biesen
FEATURE EXTRACTION OF ONE PORT SCATTERING PARAMETERS FOR SINGLE ENDED LINE TESTING

In order to identify if a subscriber loop is suitable for DSL service, the transfer function of the loop has to be estimated. Several measurement techniques exist, however Single Ended Line Testing is gaining much attention lately. This method allows only measuring at the central office side and yields a reflectogram. One of the critical issues in the estimation of the transfer function from this data is the correct extraction of the features of the reflectogram. This paper presents a new feature extraction algorithm for a previously reported transfer function estimator. It starts by explaining the previously reported algorithm. Its main drawbacks are modelling errors and loss of information due to the iterative approach. The paper explains how the new algorithm tackles these problems. The new method strongly relies of the first and second derivatives of the reflectogram, which is a completely new approach. Finally, the efficiency of both algorithms is compared. The improvements are both in terms of accuracy and identification time.

Damiano Crescini, Daniele Marioli, Andrea Taroni, Emilio Sardini, Marco Romani
NEW TEST STRUCTURE FOR INVESTIGATION OF THE PIEZORESISTIVE EFFECT IN HIGH TEMPERATURE

In different industrial applications, such as injection molding and/or hot rolling, it is necessary to measure pressure in critical environmental conditions where the temperature can reach values in the range of 350-380°C. In these cases, a fluid with low thermal conductivity is now typically used in order to transfer the pressure to the sensitive element, while preserving it from overheats. A preferred solution would be that of obtaining new sensing elements with an intrinsic capability of operation over an extended temperature range. Silicon piezoresistors are unsuitable for use in high-temperature applications due to the significant decrease of the piezoresistive effect in this material with rising temperature. On the other hand, piezoresistive films in SiC has been recently investigated as a material exhibiting a piezoresistive effect, which appears to be exploitable at high temperature. The purpose of this work is, therefore, to investigate the possibility of developing a testing structure to evaluate the longitudinal and transverse guage factors (GFL and GFT) in piezoresistive films in SiC, to evaluate the TCR and finally to define the temperature effect up to 400°C.

Pedro M. Rodrigues, Pedro M. Ramos
DESIGN AND CHARACTERIZATION OF A SUN SENSOR FOR THE SSETI-ESEO PROJECT

Sun sensors are used to measure the orientation of the satellite in orbit using the sun as a reference. This paper includes the preliminary design of a sun sensor, the design and implementation of an automatic testing system and a preliminary characterization of the most important components.

Zbigniew Czaja, Romuald Zielonkonty
MEASUREMENTS OF CIRCUIT FUNCTIONS OF ANALOG PARTS OF MIXED-SIGNAL SYSTEMS BY MICROCONTROLLERS

In the paper, two approaches to measurements of circuit functions of analog parts of mixed-signal systems controlled by microcontrollers are presented. They base on the utilization of internal resources of the microcontrollers. The first approach uses an analog to digital converter (ADC), an analog comparator and a timer. The second one uses only the ADC and the timer. The measurement procedures are realized also by the microcontroller. As an example, the transfer voltage function of a circuit function was chosen.

Page 852 of 912 Results 8511 - 8520 of 9113