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Page 845 of 938 Results 8441 - 8450 of 9371

Anil Agarwal, Claude Jacques
A SYSTEMATIC APPROACH TO ESTIMATING UNCERTAINTY IN PRESSURE MEASUREMENT

For any measurement to be meaningful, the result of the measurement must be accompanied with a statement of its uncertainty. The evaluation of uncertainties associated with pressure measurement is sometimes complex but an important task. This paper presents a systematic approach for estimating measurement uncertainty by providing a worked example for the case of pressure measurement by a pneumatic dead-weight tester.

Paulo R. G. Couto, Luiz Henrique Paraguassu, Leonardo Rodrigues Cinelli, Ilca Lopes.Bezerra, Isabela Wanderley Alves, Walmir Sérgio da Silva
VERIFICATION OF THE CONVERGENCE BETWEEN ISO GUM 95 vs MONTE CARLO METHOD REGARDING THE EXPANDAD UNCERTAINTY AT THE PRESSURE LABORATORY IN BRAZIL

This paper describes the way by which the National Pressure Laboratory in Brazil has been calculating its calibration measurement capabilities (CMC) using the uncertainty estimations contained in the ISO GUM 95 and declared in the appendix C of the BIPM, and verifying if there is any convergence and consistency between the measurements results calculate with both methods.

Felix Sharipov, Guilherme Bertoldo
NUMERICAL MODELLING OF PIRANI SENSOR

Numerical calculations of heat flux in the Pirani sens were carried out for a wide range of the gas rarefaction based on the kinetic Boltzmann equation. To take into account a non-diffuse gas-surface interaction the Cercignani-Lampis scattering kernel was used in the boundary condition. Such a kernel allowed us to study the influence of the momentum and energy accommodation coefficients on the heat transfer from the sensor wire into surrounding gas. The present results can be applied to improve the precision of pressure measurements by Pirani sensor.

Jorge C. Torres-Guzmán, Luis A. Santander-Romero, Luiz H. Paraguassú, Paulo R. G. Couto, Ilca L. Bezerra
SIM VACUUM COMPARISON FROM 13 Pa UP TO 1,33 kPa

This comparison constitutes the first vacuum comparison among National Metrology Institutes (NMI) within the Interamerican Metrology System (SIM). Each laboratory used its national standards. The Centro Nacional de Metrología (CENAM, Mexico) used a primary standard (static expansion system type) and the Instituto Nacional de Metrologia, Normalização e Qualidade Industrial (INMETRO, Brazil) used a secondary standard (comparison system type). CENAM had the role of coordinator and pilot laboratory. The comparison started in December 2004 and finished in March 2005. The objective of the comparison was to estimate the level of agreement for the realization of the quantity and the uncertainty associated to its measurement.
One transducer (Capacitive Diaphragm Gauge) was used as transfer standard; the comparison range was selected from 13 Pa to 1,33 kPa. The relevant aspects of the measurement protocol are summarized in the paper but were widely developed in the comparison reference documents. The gas used for the comparison was nitrogen. The measurements started at the lowest pressure and the pressure was increased up to the maximum range. The analysis of measurements comparability between the laboratories is included here. This bilateral comparison has been entered within the SIM data base as a pilot comparison SIM.7.26 P.

SamYong Woo, InMook Choi
INVESTIGATION OF CHARACTERISTICS OF 133 Pa CDG USING PRESSURE BALANCE

The purpose of this paper is to investigate the characteristics of precise low-pressure gauges such as Capacitance Diaphragm Gauge (CDG) devices in the range 133 Pa using a commercial gas-operated pressure balance. Generally the pressure balance is not adequate to calibrate such low pressure gauges as the minimum pressure to balance the tare weight corresponds to a pressure of several kilopascals. However using a variable bell-jar pressure method can overcome this difficulty. To realize this method effectively, we developed a new weight-handling device that makes it possible to add or remove weights easily. This apparatus is very useful to find the characteristics of such low-pressure gauges. Moreover, one of the greatest benefits of this method is the traceability to link directly to the gas pressure standard that is easily traceable to the national standard.

Alberto C. G. C. Diniz, Alessandro B. S. Oliveira, João Nildo de Souza Vianna , Fernando J.R. Neves
DYNAMIC CALIBRATION METHODS FOR PRESSURE SENSORS AND DEVELOPMENT OF STANDARD DEVICES FOR DYNAMIC PRESSURE

This paper presents state-of-the-art research being carried out in Brazil for the development of methods and devices used in the dynamic calibration of pressure sensors. The work is part of an effort set forth to set up a national reference laboratory. The devices developed and their metrological characteristics are presented.

Jaroslav Kadlec, Radimír Vrba, Radek Helán
PRESSURE SENSING VIA OPTICAL INETRFEROMETRIC PRINCIPLE

This paper describes steps involved in a new type of pressure sensing. Significance of this approach and propose approaches for improving sensitivity, resistance to electromagnetic interference, dimensions and accuracy. The goal of the project is the research of complex smart pressure sensor based on the new sensing system with galvanic fiber optic isolation including research and experimental validation of this new pressure sensing principle.
The objectives of the project of applied research are in new methods and technology of pressure sensors with galvanic isolation and function specimen of smart optical pressure sensor for explosive industrial environment and/or environment with high electromagnetic interference and very high precision and absolute resistance to electric and magnetic interference.

Myroslav Tykhan, Liubomyra Kolochenyk
METHOD FOR INPUT SIGNAL RESTORATION DURING DYNAMIC PRESSURE

One of the methods for input signal restoration during dynamic pressure measurement in real time and its relevant piezoresistive sensor are proposed.

Jorge C. Torres-Guzmán, Pablo Olvera-Arana, Luiz H. Paraguassú, Paulo R. G. Couto
COMPARISON BETWEEN INMETRO (BRAZIL) AND CENAM (MEXICO) ON BAROMETRIC PRESSURE, RANGE FROM 80 kPa UP TO 115 kPa

This paper presents the comparison between the Instituto Nacional de Metrologia, Normalização e Qualidade Industrial (INMETRO, Brazil) and the Centro Nacional de Metrología (CENAM, Mexico) on barometric pressure in the range from 80 kPa up to 115 kPa. This comparison was carried out at the end of 2004 and has been entered within the data base of the Sistema Interamericano de Metrología (Interamerican Metrology System, SIM) as comparison SIM.7.25 P. The pilot laboratory was CENAM. The standards used by the national laboratories were pressure balances, operated in free deformation. The transfer standard used for the comparison was a digital barometer, accuracy class of 0.01 % of full scale. Eight points of pressures were selected and each pressure was measured four times. The results obtained by the two laboratories were in agreement.

Davor Zvizdic, Lovorka Grgec Bermanec, Tomislav Stasic
REALIZATION OF NATIONAL ABSOLUTE PRESSURE STANDARD AT LPM

This paper presents absolute pressure calibration system in the range from 25 kPa up to 2 MPa which is being developed in Croatian national pressure laboratory- Laboratory for Process Measurement (LPM) at Faculty of Mechanical Engineering and Naval Architecture (FSB) in Zagreb.
Design of the system, theoretical basis, effective area determination methods and the model for estimation of absolute pressure measurement uncertainty are described.

Page 845 of 938 Results 8441 - 8450 of 9371