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Page 718 of 977 Results 7171 - 7180 of 9762

Damir Ilic, Alan Šala, Ivan Lenicek
PREDICTION OF THE OUTPUT VOLTAGE OF DC VOLTAGE STANDARDS

In this paper we report some methods which upgrade the measurement uncertainty evaluation in analysis of the prediction of the output voltage of DC Reference Standards (Fluke 732A at 1 V, 1.018 V and 10 V levels). The monitoring of long-term stability of Zener-based voltage reference standards is one of the main tasks of Primary Electromagnetic Laboratory (PEL), which is a part of the Faculty of Electrical Engineering and Computing of the University of Zagreb, and a holder of national standards of voltage in Croatia. The long-term stability of its DC Reference Standard has been analysed according to the calibration data obtained in different laboratories over a period of more than twenty years. The weighted least-squares fitting was used and the regression coefficients were calculated, by which the maintained voltages at all three outputs can be predicted for a moment of interest. This approach significantly reduces the uncertainties of the maintained voltages.

Anna M. Ryniewicz, Andrzej Ryniewicz
THE GEOMETRY ESTIMATION OF THE ARTICULATION CARTILAGE SHAPE AND DEFECT DIAGNOSIS USING MAGNETIC RESONANCE IMAGING

MRI of the knee is the most frequently requested MR joint study in musculoskeletal radiology. MRI gives a comprehensive examination of the knee, providing surgeons with information they cannot obtain clinically or invasively. In this paper there is estimated the sensitivity of the articulation cartilage defects imaging using MR. There were examined two animal and two human specimen knees using CT, MRI and coordinate control machine (CCM). The cartilage was artificial destroyed and the defects were measured using MRI and CCM. CT was done to verify bone damage. The outcomes obtained in MRI and CCM are approximately.

Andrzej Ryniewicz
THE ANALYSIS OF THE GEOMETRY OF OSSEOUS TISSUE OF THE BIOLOGICAL BEARINGS INTERACTION ZONE IN THE ASPECT OF ACCURACY OF SHAPE MAPPING

This paper presents the problem of the assessment of the shape of osseous tissue and the size of the occurring defects using the diagnosis of computer tomography. The results of assessment of shape of chosen osseous element were presented. In second part the exampled artifacts were presented and the own artifacts elaborated in Cracow University of Technology to assess the accuracy of CT were proposed.

Ksenia Sapozhnikova, Roald Taymanov
MULTIPARAMETRIC MEASUREMENTS OF EMOTIONS

A concept of the model intended for measuring emotions is grounded. The efficiency of evolutionary analysis when forming the model of measuring the emotions which are contained in acoustic and visual impacts is demonstrated. The possibility to develop a corresponding measurement instrument is shown.

Peter Benkó, Rudolf Palencár
UNCERTAINTIES IN THE WHOLE RANGE OF THE CALIBRATION OF A THERMOCOUPLE

This contribution describes the procedure of evaluating the calibration of thermocouple by means of its comparison with the thermocouple standard. In the process of thermocouple calibration by means of comparison, the resulting uncertainty specified by applying the generalized procedure for evaluating the calibration of measuring devices with continuous scale. The advantage of this method of evaluation is the determination of uncertainties in the whole range of the calibration. The conclusion of this paper states the illustrated differencies between cases when covariances are into account or are not.

Tomasz Adamskl, Wieslaw Winiecki, Jakub Olszyna
ALGORITHMS AND CIRCUITS FOR LOW POWER SECURED SENSOR NETWORKS WITH ASYMETRIC COMPUTATIONAL RESOURCES

The paper deals with applications of cryptographic methods in design of secured versions of Distributed Measurement Systems (DMS). In the paper wide range of cryptographic algorithms is assessed and some of them are chosen and proposed as well suited to DMS specific requirements. Some specialized low power, high speed, hardware solutions for cryptographic algorithms are also suggested in the paper. Strong asymmetry of computing power and memory capacity is taken into account in both software and hardware solutions.

Inácio Bianchi, Paulo Magalhães Filho, José Pinto Ferreira Sobrinho
POWER PERFORMANCE EVALUATION OF AN ELECTRIC HOME FAN WITH TRIAC-BASED AUTOMATIC SPEED CONTROL SYSTEM

In order to provide a low cost system of thermal comfort, a common model of home fan, 40 cm diameter size, had its manual four-button control system replaced by an automatic speed control. The new control system has a temperature sensor feeding a microcontroller that, by using an optic coupling, DIAC or TRIAC-based circuit, varies the RMS value of the fan motor input voltage and its speed, according to the room temperature. Over a wide range of velocity, the fan net power and the motor fan input power were measured working under both control system. The temperature of the motor stator and the voltage waveforms were observed too. Measured values analysis showed that the TRIAC-based control system makes the fan motor work at a very low power factor and efficiency values. The worst case is at low velocity range where the higher fan motor stator temperatures were registered. The poor power factor and efficiency and the harmonics signals inserted in the motor input voltage wave by the TRIAC commutation procedure are correlated.

Jakub Bach, Romuald Masnicki, Janusz Mindykowski
THE MEASURING INSTRUMENT WITH DISTRIBUTED DATA PROCESSING

In the paper a concept of the measuring instrument with distributed data processing, cooperating with PC is presented. A functional configuration of the instrument performing additional functions connected with measurement result accuracy assessment as well as respective algorithms are shown. The principles of cooperation with PC computer are discussed. The laboratory implementation of the designed instrument and scope of its use for teaching process is proposed.

Mark Schiefer, Richard Bono
IMPROVED LOW FREQUENCY ACCELEROMETER CALIBRATION

This paper will discuss a newly developed implementation of low frequency accelerometer calibrations below 10 Hz. The goal is an improved low frequency accelerometer calibration methodology capable of performing superior quality measurements with significantly lower uncertainties while maintaining good throughput and the simplicity of traditional back-to-back calibration techniques. By using an optical encoder as the measurement reference instead of a traditional back-to-back reference accelerometer, limitations due to shaker stroke length are nearly eliminated, with the practical limitation for a quality calibration measurement at ultra low frequency being the resolution of the sensor under test itself.

Mariusz Szweda
DWT ANALYSIS OF SELECTED TRANSIENT AND NOTCHING DISTURBANCES

This paper is focused on the problem of transient and notching analysis occurring in electric power system. The aim of the research was to improve DWT algorithm especially for transient detection, in order to increase performance of a multi-parameter DSP system. The method described in the paper proposes rejecting insignificant wavelet decomposition stages and takes only these stages for reconstruction transient or notching, in which predominant energies were detected. The criterion of rejecting stages is that the frequency band of disturbances reconstructed in this way should be sufficient for further evaluation. The proposal is similar to idea of data compression by DWT. All analyses are based on the real voltage samples, registered in the real isolated electric power system, namely ships' systems. Finally, the results of the research are presented and commented on.

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