IMEKO Event Proceedings Search

Page 839 of 914 Results 8381 - 8390 of 9134

Petr Benes, Stanislav Klusacek
ONLINE MEASUREMENT OF THE PARTICLE SIZE DISTRIBUTION

New principle of the particle size distribution measurement is described. We analyze acoustic emission signal generated by a flow of particles impacting on a fixed obstacle. Changes of the power spectral density of the signal are well correlated with the particle size distribution. Our method was successfully used for measurement of particle size distribution in the range from 1mm to 10 mm of the ferrous sulphate monohydrate in real chemistry process. Particles were measured at the output of the dry kiln (temperature 150-200 °C, mass flow 4 tons/hour), where it is not possible to use any of other known principles such as particle vision, laser diffraction analyzers, ultrasonic analyzers, focused-beam reflectance measurement etc.

Will Almeida, Bruno Costa, Raimundo Freire, Francisco Santos, Sebastian Catunda
WIND TUNNEL FOR TEST OF SENSORS APPLIED TO ANEMOMETRYN

The wind tunnel development with wind speed control is presented in this paper using an ultrasonic anemometer. It were used the Time Difference and Phase Difference methods in the measurement of the air speed, and the circuit used for the measurement as for the speed control it was based on a microcontroller and an motor (fan). The experimental results obtained from the proposed circuit are compared with a commercial anemometer. The analysis of temporal response performance of the fan speed control circuit was developed to validate the proposed system.

Karina Chacur Schraml, Valmir Ruiz
UNCERTAINTY AND ERROR EVALUATION OF A FLOW DIVERTER VALVE ACTUATED BY A PNEUMATIC PISTON

The purpose of this study is to estimate the uncertainty contribution due to the diverter valve in the total uncertainty, concerning the calibration of flow meters in the water laboratory of the Center for Fluid Metrology.

Przemyslaw Otomanski
THE USAGE OF THE APPROXIMATE METHODS TO DETERMINE THE UNCERTAINTY OF RELATIVE HUMIDITY MEASUREMENT USED TO INTEGRATED HUMIDITY SENSORS

Results of experiments concerning humidity measurements have been presented in the paper. Integrated humidity sensors were used for the experiments, which transformed the value measured into a corresponding capacity. The structure of a measuring system was described, and the requirements concerning particular elements of the measuring track were defined. Using the regression method, an analytical equation was modeled, combining the output capacity value of the sensor with the examined humidity changes. With the use of experimental results as well as the least square method, the values for the above equation’s parameters were determined. The knowledge of coverage factor characteristics for the convolution of four selected probability distributions was used for the research.

Gilder Nader, Claudia dos Santos, Paulo J. S. Jabardo, Monica Cardoso, Nilson M. Taira, Marcos T. Pereira
CHARACTERIZATION OF LOW TURBULENCE WIND TUNNEL

Wind tunnels with uniform velocity profiles and low turbulence are used to calibrate air velocity sensors such as anemometers and Pitot tubes among others. These wind velocity sensors are used in cases such as, for example, eolic turbines towers, meteorological stations, hospitals, etc. To make calibrations with high precision and accuracy it is necessary a wind tunnel with low turbulence (less than 0.4%) and uniform velocity profile in the test section. This study presents a characterization of the low turbulence wind tunnel of the Anemometry Laboratory of IPT (Institute for Technological Research), in which the calibrations are done in the discharge of the wind tunnel and the working range is from 2 m/s up to 40 m/s. A turbulence intensity less than 0.4% and a mean velocity variation of ± 0.2 % was obtained.

R. Kramer, B. Mickan, D. Dopheide
DOUBLE PISTON PROVER USABLE AS FLOWRATE COMPARATOR FOR VARIOUS GASES

For the calibration of small flowrates and for use with different gases, a novel double piston prover with a spindle-stepper motor drive has been developed. The piston prover allows flowrates being generated with a very good reproducibility and flowrate constancy, and it therefore also makes possible the calibration of meters under test which generate a constant flowrate like critical nozzles. By means of this principle, it was possible to realize for the first time a flowrate comparator which can also be used for the measuring of gas flows.

Luca Mari
ON THE MEASURAND DEFINITION

Among the sources of measurement uncertainty, the GUM [ISO 1995] lists the incomplete definition of the measurand. Because of its relevance to the very concept of measurement uncertainty, a short analysis of the problem of the definition of the measurand is worth.

Koichiro Hattori, Takashi Usuda
PRIMARY HARDNESS STANDARD OF BRINELL HARDNESS IN JAPAN

In the hardness standard, the top of national traceability chain is the primary hardness blocks. The National Metrology Institute of Japan (NMIJ) will start calibration service of primary Brinell hardness blocks. The uncertainty of the Brinell blocks is considered following to the test conditions presented in the paper.

Yohei Kayukawa, Ken-ichi Fujii, Yuya Kano, Haruki Sato
DENSITY STANDARD LIQUIDS OF NEW CONCEPT BY THE MAGNETIC LEVITATION

The major uncertainty factor of the magnetic levitation densimeter, which is one of the most accurate densimeter, is the force transmission error caused by the magnetism of the fluid. We have examined this effect by FEM, and pro- posed a new method for the magnetic levitation densimeter.

Daniele Gallo, Carmine Landi, Nicola Pasquino, Nello Polese
A METHODOLOGY FOR QUALITY ASSURANCE IN ENERGY MEASUREMENTS UNDER NON-SINUSOIDAL CONDITIONS

The evaluation of the electrical energy flows is at the base of all operations connected to the commercial transactions in energy market. The assessment of "metrological quality" of the power/energy measuring apparatuses is well establishes in ideal sinusoidal conditions. But, with increasing diffusion of power electronics the typical characteristics of power network are far from sinusoidal one. In this paper a new methodology for quality assurance of energy meters in non sinusoidal operating conditions is reported. The description of methodology and some experimental results obtained are discussed in detail.

Page 839 of 914 Results 8381 - 8390 of 9134