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Page 849 of 977 Results 8481 - 8490 of 9762

Pedro M. Ramos, Tomáš Radil, Fernando M. Janeiro, A. Cruz Serra
DSP Based Power Quality Analyzer using New Signal Processing Algorithms for Detection and Classification of Disturbances in a Single-phase Power System

This paper describes the prototype of a power quality analyzer designed for real-time detection and classification of disturbances that occur in a single-phase power system. The previously developed algorithm for disturbance detection and classification was improved and implemented in a standalone DSP based analyzer. Its performance was verified during long term monitoring of the power system.

Pedro M. Ramos, Fernando M. Janeiro, Mouhaydine Tlemçani, A. Cruz Serra
Implementation of a DSP Based Impedance Measurement Instrument Using Ellipse Fitting Algorithms

In this paper, the DSP implementation of an impedance measurement instrument based on ellipse fitting algorithms is described. The system prototype is based on a commercial DSP kit with few external electronics for baseline assessment and requirements definition. The implemented system is tested for impedance magnitudes from 100 Ω up to 15 kΩ, phases in the ±90º range at 1 kHz measuring frequency with extremely good results.

Pasquale Arpaia, Pasquale Cimmino, Fabrizio Clemente, Carmine Romanucci
A Microcontroller-based Instrument for Prostheses Osseointegration Measurement by Electrochemical Impedance Spectroscopy

A method based on Electrochemical Impedance Spectroscopy (EIS) for the diagnosis of prosthesis osseointegration was proposed by the Authors in previous works. In this paper, the design, the implementation, and the metrological characterization of a microcontroller-based prototype conceived as a stand alone instrument to be used for in-vivo clinical applications are presented. The preliminary experimental results of laboratory evaluation are presented.

Camelia Petrescu, Lavinia Ferariu, R.Olaru
Genetic Algorithm Combined with Finite Element Method for Optimum Design of Ferrofluid Actuator

This paper presents a case study concerning the optimization of a DC ferrofluid actuator designed to transmit small pressures, using genetic algorithms. The optimization problem consists in finding the values of some mechanical parameters of the actuator as well as those of the magnetic permeabilities of the device components, that render a maximum equivalent force. The magnetic field inside the actuator is determined using the finite element method and the force acting on the flexible parts is calculated using Maxwell’s magnetic tensor.

U. Pogliano, C.G. Bosco, M. Lanzillotti, D Serazio
Ac-dc transfer standard shunts for frequencies up to 1 MHz

A new type of coaxial shunt for high frequency ac-dc current transfer standards has been designed. The structure of the shunts with nominal current from 100 mA to 5 A are made of a disk with two coaxial conductive layers in one side. SMD resistors are soldered in parallel between the two layers. Two conductive screens are applied in both side of the disk. In order to reduce stray effects, the structure has ideally no common magnetic interaction between the input current and the output voltage and practically a very low section where the magnetic field is confined, so allowing a flat response in a wide frequency range.

Warsza Zygmunt Lech
Accuracy measures of the four arm bridge of broadly variable resistances - Part 1: Backgrounds, general case of four variable arms

After short introduction the open circuit output voltage of four-arm resistance (4R) bridge supplied by current or voltage is given. Normalized forms of its current to voltage and voltage to voltage open circuit transmittances are defined. The simplified description of accuracy of the broadly variable resistance by instantaneous, limited and random errors of its initial value and of increment is introduced. Borders (the worst cases) of the field of its possible error values are found for constant values of both this limited errors. Accuracy measures of current to voltage transmittance, i.e. instantaneous and limited errors and mean square random measures (probabilistic errors or uncertainties) are discussed in detail for general case of arbitrary variable all bridge arms. Basic formulas together with their equivalents for voltages transmittance are completed in the table 1. Literature is included. Accuracy description of other common in practice particular cases of the 4R bridge and example of its application for temperature sensors Pt 100 are described in the part 2. Final conclusions are also there.

Dorozhovets Mykhaylo, Warsza Zygmunt Lech
Methods of upgrading the uncertainty of type A evaluation (2) - Elimination of the influence of autocorrelation of observations and choosing the adequate distribution

It is the continuation of a previous paper, in which limitations of uncertainty type A estimation due international guide GUM, are shortly discussed and method of elimination of influence of unknown systematic components: trend and oscillation, are introduced. Below two next proposals of development and upgrading of the method type A are presented, i.e. taking in estimation the influence of autocorrelation of observation resultants and choosing the adequate type of their probability distribution by ?2 criterion, if is different that normal one, are considered. It is illustrated by numerical examples of normal, rectangular and Laplace distribution. Results are compared to parameters calculated by the actual GUM method. Conclusions and background literature are included.

Zygmunt Lech Warsza, Adam Idzkowski, Jaroslaw Makal
Experimental verification of the double-current supplied bridge circuit in 2D measurements of strain and temperature

A four-terminal (4T) bridge circuit unconventionally supplied by two current sources connected in parallel to opposite arms, named double current bridge (2J) is presented. It has two different outputs from both diagonals. Their output voltages are described as functions of arm resistances and their increments from the bridge balance in relative units are given. Example of its application in two-parameter simultaneous (2D) measurements of the strain and temperature is presented. Formulas of their signals and details of the designed conditioning circuit are given. Some results of experimental verification of this instrumentation are shortly mentioned.

U. Pogliano, B. Trinchera
RMS Voltage Measuring System for Precise Evaluation of Electric Quantities

This paper is about the design and the construction of a system for the measurement of the RMS voltage. One or more of these systems can be employed as building blocks for a wide range of applications in the field of electrical metrology. The first implementation demonstrated its functionality and the possibility to reach a stability of the AC voltage measurement in a wide frequency range with an accuracy within 10 parts in 106, limited only by the DC voltage accuracy of the DAC employed.

Oleh Velychko
Using Of Uncertainties Estimation In International Standards

Peculiarities of uncertainty estimation in GUM and IEC international standards are shown. The correct use of GUM for expression of measurements uncertainty in development of new and reconsideration of old international standard is recommended.

Page 849 of 977 Results 8481 - 8490 of 9762