IMEKO Event Proceedings Search

   

Page 742 of 977 Results 7411 - 7420 of 9762

Vaclav Papez, Stanislava Papezova
ANALYSIS OF SIGNAL NETWORK NON-LINEARITY IN A METROLOGICAL LABORATORY

Test signals that are used by high precise measuring have to contain minimum harmonic components of basic frequency. All non-linearity in electronic circuits may be sources of harmonic components in testing signals. Traditional methods and new method for the small nonlinearity measuring of electronic components and circuits are described in this paper. There are presented examples of measured intermodulation product levels on transmission lines components.

Sascha Mäuselein, Oliver Mack, Roman Schwartz, Gerd Jäger
INVESTIGATIONS OF NEW SILICON LOAD CELLS WITH THIN-FILM STRAIN GAUGES

This paper discusses the usability of load cells (LCs) made of single crystalline silicon (Si) mechanical springs with sputtered-on thin-film strain gauges (SGs) as sensors for force and weighing measurements. Experimental investigations of the characteristic line in a temperature range from -10 °C to 40 °C concerning reproducibility, hysteresis and linearity are presented. The results offer the usability of the Si LC in the range of precision measurement if temperature behaviour of sensitivity and linearity are compensated.

Tassanai Sanponpute, Pramann Chantaraksa, Nattapon Saenkhum, Nittaya Arksonnarong
SUSPENDED-FULCRUM TORQUE STANDARD MACHINE

National Institute of Metrology Thailand (NIMT) has designed and developed suspended-fulcrum torque standard machine. The main design is to replace air bearing with the 30-µm-sheet metal as a fulcrum. The advantages of the design are the lower cost and maintenance than air bearing-fulcrum type. The experiment was done to evaluate the sensitivity of the suspended fulcrum, which is directly affected by the bending stiffness of the thin metal sheet. Also, the different between left and right arm length is calculated from the trimmed mass used for equilibrium balancing at each applied torque. Finally, all the uncertainty of fulcrum, weight set and arm length are used to calculate the relative expanded uncertainty of torque measurement, which is 5 × 10-5.

Jacek Piskorowski, Roman Kaszynski, Miguel Angel Gutierrez de Anda, Arturo Sarmiento-Reyes
A NEW APPROACH TO THE DESIGN OF POST-DAC FILTERS

In many measurement applications, it is required to have digital-to-analog converters (DAC). All DACs use a reconstruction (anti-imaging) filter as the final step in the conversion process. Without this filter, generating a continuous-amplitude signal would not be possible. This paper presents a new theoretical concept of a post-DAC continuous-time filter. The proposed filter was designed so as to provide both a constant group delay over the desired frequency band and a maximally flat magnitude response. Moreover, the filter coefficients were varied in the time in order to accelerate the filter response. Results verifying the effectiveness of the proposed approach are presented and compared to the performance of a traditional lowpass reconstruction filter.

Vaclav Papez, Stanislava Papezova
CONTACTLESS DIAGNOSTICS OF THIN FILM LAYERS

Thin layer resistance measurement using the change of complex coil impedance is a contact-less method for conductive layer diagnostics. The analysed sample is inserted into the leakage field of the coil. Our conclusions of a theoretic analysis have been verified in experimental arrangement with a measuring coil and a vector impedance meter. The layer sheet resistance is evaluated by electronic system. A special algorithm, ensuring the explicit evaluation of the measuring, is used for determination of the layer sheet resistance.

Daniel Belega, Ciprian Dughir
ACQUISITION SIGNALS FROM ELECTROMAGNETIC FIELD-METERS USING DIGITAL MULTIMETERS WITH EVENT LOGGING MODE

The portable digital multimeters (DMMs) frequently recommended to be used for data acquisition from electromagnetic field meters are the data logging DMMs. In this paper it is shown that it is better to use for this task the DMMs with event logging mode instead of the ones with the data logging mode. The advantages obtained using these DMMs are presented. The performed experimental results prove that the DMMs with event logging mode performed the best.

Burcu Binici Gökçen, Fatma Akçadag
DETERMINATION OF ORGANOCHLORINE PESTICIDES IN TOMATO AND EVALUATION OF PROFICIENCY TESTING RESULTS

In this study proficiency testing (PT) scheme on determination of organochlorine pesticides in tomato which is organized by TUBITAK National Metrology Institute (UME), is evaluated. Participating laboratories are supposed to analyse Endosulfan I, Endosulfan Sulfate, Alpha-BHC, Heptachlor, Aldrin and 4,4 DDD pesticides in tomato. The aim of proficiency testing scheme organization is to evaluate of performance of laboratories which analyse the pesticide residue in tomato.

Valentin Batagelj, Jovan Bojkovski
NOISE AND INTERFERENCE IN THERMOMETRY RESISTANCE BRIDGES

This paper analyses the influence of interference from non-ideal laboratory environment on the resistance-bridge operation. Interference can be either the result of thermal emf, electromagnetically induced voltage or harmonic distortion of the power supply voltage. Interference is manifested as the increased measurement dispersion or even as non-negligible change in the measured resistance.
Thermal emf is the voltage generated by the temperature gradients on junctions of different metals. Resistance bridges are cancelling this effect by using either alternating current or DC current reversal.
Electromagnetic interference is air transmitted interference that generates induced voltage in the thermometer, connecting cables and/or bridge circuits. This effect results not only in unstable bridge operation and increased noise, but can also produce an offset in bridge readings.
Ideally, AC power supply voltage would be pure sine with constant frequency, phase and amplitude, but in practice it is often distorted. Higher order harmonics and/or subharmonics may interfere with the bridge operation.
Experiments with interference sources were conducted on the DC resistance bridge MI6010 and the AC resistance bridge ASL F900. The results were compared and advantages and not only disadvantages of AC and DC principle were outlined, but also some practical recommendations for the reduction of interference are given based on practical observations and experiments.

Jovan Bojkovski, Valentin Batagelj, Janko Drnovšek, Vincencij Žužek
PRACTICAL LIMITS OF MEASUREMENT UNCERTAINTIES IN CALIBRATION OF STANDARD PLATINUM RESISTANCE THERMOMETERS BY COMPARISON

Usually, SPRTs are calibrated at fixed points, but due to the high cost of a primary realization of physical quantities and time needed for the calibration at fixed points, it can be reasonable to calibrate them by comparison at the highest level.
The calibration by comparison is a technique most widely used to calibrate measuring instruments, not only in industry but also in many secondary calibration laboratories. Calibration procedures of a typical secondary laboratory are based on the use of transfer standards, which are usually calibrated in a primary laboratory, thus providing traceability to (inter)national standards through a process of dissemination of a unit with an associated uncertainty.
The aim of the paper is to show that temperature calibrations by comparison, in the range from –95 °C up to 300 °C, can result in a calibration uncertainty (k = 2) of 0,005 °C, which is sufficiently low for many industrial applications and secondary calibration laboratories.

M. Jedrzejewska-Szczerska, Ryszard Hypszer, Bogdan B. Kosmowski
OPTIMIZATION OF THE FIBER-OPITC FABRY-PEROT INTERFEROMETER CONSTRUCTION

In this article authors present the optimization of fiber-optic Fabry-Perot interferometer to attain the maximum resolution and accuracy of the sensor. The low-finesse Fabry-Perot interferometer working in reflective mode has been implemented. This interferometer was chosen for optimization because using it can have a lot of applications in practice. Its advantages are: relatively simple configuration, potentially low cost, high resolution and low inertia on temperature changes. Furthermore, because of its small size it is possible to make nearly point wise measurement. Authors present theoretical analysis and experimental results of optimization of the fiber-optic Fabry-Perot interferometer, which has been designed and elaborated at our laboratory.

Page 742 of 977 Results 7411 - 7420 of 9762