## IMEKO Event Proceedings

Page 786 of 851 Results 7851 - 7860 of 8504

**THREE-PHASE FLOW MEASUREMENT USING CORIOLIS MASS FLOW METERING**

This paper describes a new three-phase flow metering technology, combining Coriolis mass flow and water cut readings and without applying any phase separation. The system has undergone formal laboratory trials at NEL, UK and at VNIIR, Kazan, Russia; a number of field trials have taken place in Russia. Results from the NEL trial will be described in detail. Initial experiences from field trials will also be described. Together, these results demonstrate the potential for using Coriolis mass flow metering combined with water cut metering for three-phase (oil/water/gas) measurement.

**THRESHOLD ADAPTATION IN AUTOMATIC WAVELET-ICA FOR ELECTROENCEPHALOGRAPHIC ARTIFACT REMOVAL**

Electroencephalography (EEG) is a well established methodology to record the electrical activity of the brain. We can be interested in monitoring the cerebral electrical activity for different purposes: studying the cognitive activity, interfacing the brain with the machine, extracting diagnostic information, etc. Artifacts are unwelcome signals, generated by electromagnetic sources not related to cerebral activity, that may overlap to the EEG signals and affect their processing. Whatever the goal of EEG processing, a preprocessing step consisting in artifact removal is normally required. Unfortunately, artifact removal is unavoidably a lossy procedure, therefore, the goal must be removing artifacts losing the minimum amount of useful information embedded in the EEG. To this purpose, Automatic Wavelet-ICA was recently proposed by the authors. The technique is multistep and parameter dependent, thus its performance may vary signi?cantly with the parameter setting. The present paper shows the results of the optimization with respect to the threshold used for artifact detection.

**Threshold estimation in least-squares error functions: Application to impedance spectroscopy**

Least-squares error functions are widely used in the determination of the parameters of models of a system. When this procedure is iterative, the problem of deciding when to stop iterating arises. Usually a threshold is defined, so that when the error function falls below this value, the least-squares error procedure can be stopped and the solution is found. However, this threshold depends on the uncertainty of the measurements. In this paper, the cost function PDF (probability density function) is analyzed to obtain a closed-form expression for the estimation of this threshold, in the framework of impedance spectroscopy.

**THz time-domain spectroscopy: investigation of thin layers of inks**

We develop an original experimental procedure and a comprehensive method of data analysis to measure the optical parameters of drawing media in the THz spectral range. The method based on the THz – Time Domain Spectroscopy is applied to recover material parameters on drawing inks deposited on polyethylene pellicles with thicknesses down to tens of micrometers. In particular, we investigated three commercial inks: a red ink (based on cochineal carmine), a blue ink (indigo) and a black ink (irongall). The implemented experimental procedure and numerical method enable us to extract the absorption coefficient and refractive index spectra in an absolute scale, opening the possibility to investigate the material parameters in the THz range with a complete quantitative study.

**TIME – FREQUENCY ANALYSIS OF NON-STATIONARY MAGNETIC FIELDS**

The paper considers applying the quadratic joint time – frequency transform for the spectral analysis of the non-stationary magnetic fields. The general properties, advantages and disadvantages of the quadratic algorithms from Cohen’s class like the short – time Fourier transform (STFT) spectrogram and the pseudo Wigner – Ville (PWV) distribution as well as the adaptive spectrogram are discussed. The selected results of the off-line time-frequency analysis of the recorded signals of magnetic field of ship bow thrusters drive with frequency converter are presented. Performed time-frequency analysis enabled the signal identification in time periods. If the frequency contents of the analyzed signal don’t change rapidly, then the STFT spectrogram can be applied with relatively wide window function, to obtain a good frequency resolution. The PWV distribution is useful for analyzing signals that have widely separated components for which a fine time-frequency resolution is required. The adaptive algorithm is characterized by the most accurate detection of investigated nonstationary components, but it requires more computation time, which is suitable only for off-line analysis.

**Time and Frequency Domain Tests for ΣΔ Modulators**

The paper deals with the classification method of some architectures of ΣΔ modulators. The classification is based on the analysis of the different trends of the output signals characterizing some ΣΔ modulator architectures. The method operates (i) by feeding the ΣΔ modulator with sinusoidal signal, and (ii) by analysing the output signals in the time or in the frequency domain. The classification consists in (i) distinguishing between low pass and band pass ΣΔ modulator, (ii) identifying both the Single Quantizer Loop (SQL) and the Multistage Noise Shapers (MASH) architecture, (iii) evaluating the levels of the quantizer block inside the SQL architecture, and (iv) detecting the number of cascaded stage inside the MASH architecture. In order to validate the proposed method, numerical tests are performed by referring to the noumerous architectures of ΣΔ modulators proposed in the relevant literature.

**TIME DEPENDENT PERFORMANCE OF TURBINE GAS METERS**

Gastransport Services in the Netherlands, uses turbine gas meters to measure the gas flow to local gas distribution companies, large industrial customers and power plants GTS operates approximately 1100 city gate stations, at a delivery pressure of usually 8 bar.

In the Netherlands, the procedures for determining the operational performance of the turbine meters are agreed upon between Gastransport Services and its customers. As a result of this agreement, Gastransport Services inspects the total population of turbine meters by means of the well-known variables-acceptance-sampling. Each year, 60 turbine meters are selected randomly from the total population. Subsequently, the selected turbine meters are calibrated traceable to international standards by Netherlands Measurment Institute (NMi). The information from these recalibrations is used to study the stability of the turbine meters.

Because, through the years a lot of information has been gathered on the turbine meters performance, the presence of statistically significant relationships (correlation) between the performance in time of the meters on the one hand and properties like the construction year, the pressure class, the size, the maximum allowable flow rate and/or the recalibration period of the meter on the other hand, can be investigated. In this presentation, analysis-of-variance and the quadrant-correlation-test are used to test for the presence of such correlations.

The aforementioned five properties were analysed for the presence of correlation at two different calibration pressures and with different definitions of drift to express the performance in time of gas turbine meters. For a specific calibration pressure and a specific type of drift, the performance in time dependents on the recalibration period and the size of the turbine meter. Furthermore, the correlation analysis, showed that a turbine gas meter seems to reach a steady state in time, expressed in terms of shift of the weighted mean error.

**TIME DOMAIN DIAGNOSIS OF ANTICORROSION COATINGS VIA SHAPE DESIGNED MEASUREMENT SIGNALS**

The paper presents time domain diagnostic method of anticorrosion coating on the level of equivalent circuit parameter identification. The method is based on applying non-conventional, shape-designed stimuli signals and measuring the object responses (so-called observables) at a given time T. Equivalent circuit parameters are calculated directly from observables using analytical equations, determinated by modelling circuit topology. In the paper the theoretical basis of the method is presented, together with measurement methodology and simulation results for 4 elements anticorrosion coating equivalent circuit.

**TIME DOMAIN METHOD TO DETECT HARMONIC SOURCES IN UNBALANCED POWER SYSTEMS**

In recent years the problem of harmonic pollution has become more urgent, because of the development in distribution systems of non linear loads that draw non-sinusoidal currents. This paper presents a time domain method for harmonics sources detection in power systems, which can be usefully applied also in presence of unbalance or asymmetry. Harmonic power flows are calculated in real time and no spectral analysis is required for the evaluation of currents amplitudes and phase angles. The development of a new instrument is described, which is able to measure several network power quality parameters; measurement accuracy is estimated and experimental results are reported.

**TIME DOMAIN PARAMETER IDENTIFICATION OF ANTICORROSION COATING VIA SOME TYPES OF POLYNOMIAL SIGNALS**

The paper presents a time domain method of anticorrosion coating diagnosis on the level of equivalent circuit parameter identification, based on applying a set of shape-designed polynomials and measuring the object’s responses (so-called observables) at a given time T. Equivalent circuit parameters are calculated directly from observables using analytical equations, determined by modelling circuit topology. In the paper the comparison of different polynomial signals (Chebyshev, Legendre, Optimal) against the criteria of stationary error propagation is presented, on the base of analytical and simulation results.

Page 786 of 851 Results 7851 - 7860 of 8504