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F. Adamo, F. Attivissimo, L. Fabbiano, M. Savino
IMPROVEMENTS OF SEISMIC SENSOR DESIGN FOR SOIL MOISTURE MEASUREMENT

The main aim of the work is finding a general mathematical model to estimate the moisture content in the soil using seismic waves propagation, when the composition of the media is unknown. Usinf the new mathematical model here presented, the authors are developing a prototype of the sensor that will be able to measure the moisture of the soil usinf both compressional and shear waves velocity measurement.

Jerzy Nabielec
A “BLIND” CORRECTION OF DYNAMIC ERROR OF A NONSTATIONARY FIRST ORDER TRANSDUCER FOR THE PERIODIC CASE – SIMULATION INVESTIGATION

The paper presents an extension of the “blind correction” method with respect to nonstationary transducers of the first order. An analytical description of the measuring channels’ dynamics is presented for the case where both: the measured signal and the measuring channels’ parameters are varying with same fundamental frequency. The influence of the measuring system parameters on the correction accuracy was investigated using the simulation methods.

Emil Vremera, Cristian Fosalau, Luciano Brunetti
DESIGN REQUIREMENTS FOR SENSORS BASED ON AMORPHOUS WIRES RESULTING FROM MEASUREMENTS AND SIMULATION

Amorphous wires are attractive components for sensor and micro-sensor realization. The negative factors that affect the behaviors of these sensor types must be however highlighted and compensated throughout adequate tools. The characteristics of the sensing element can be carried-out starting from the measurement results. A model of a magneto-impedance sensing element is obtained and used for a PSPICE simulation next step. The paper presents the results obtained at radio-frequency, at once with the mathematical modeling of the sensitive part. In addition, there are also the requirements which must be fulfilled in the design of this kind of sensors.

Zbigniew Moron
CONSIDERATIONS ON THE ACCURACY OF MEASUREMENTS OF ELECTRICAL CONDUCTIVITY OF LIQUIDS

The purpose of this paper is the presentation of new requirements created by contemporary applications of electrolytic conductivity measurements, the main factors limiting accuracy of such measurements and also discussion of the means enabling minimization of effects caused by these factors. Recently observed demand for accurate microscale conductivity measurements, mainly in biomedical engineering, involves new features required from the conductivity sensors and co-operating electronics: miniaturization, robustness, low price (mass produced, disposable devices). Consequently, a new approach in designing such instrumentation is required.

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.

Page 847 of 907 Results 8461 - 8470 of 9067