Anna Ostaszewska, Sabina Zebrowska-Lucyk
The paper concerns one of subjective continuous quality evaluation method (SSCQE), which is used for measuring the human perception of compression errors in video. The problem with subjective quality assessment is a big measurement uncertainty that makes drawing conclusions on quality of compared materials with required significance level difficult. The paper presents a new method of measurement data processing, which enables for decreasing the unwanted influence of human factors and diminishing the standard deviation of the measurement results by a half. The Mandel's h and k statistics are...
XIX IMEKO World Congress
· TC18
· 2009
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Luka Ferkovic, Damir Ilic, Kristina Ferkovic
This paper covers the analysis of electrical parameters which affect the accuracy of current-to-voltage transducer based on Rogowski coil. The actual transducer is designed for high-accuracy measurement of AC current (up to 20 A at power supply frequency of 50 Hz, with the aiming uncertainty of 100 parts per million). The primary source of uncertainty of ac current measured by this type of transducer is non-ideal geometry (i.e. mutual position between primary conductor and secondary coils). Except these influencing parameters, the temperature dependence of coil geometry affect the accuracy...
XIX IMEKO World Congress
· TC4
· 2009
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Adam Wozniak
In this paper, a new method of testing of the repeatability of stylus change of modular probes used in coordinate measuring machines (CMMs) is proposed. The principle of the method is presented. The validity of the method is experimentally confirmed on a bridge Zeiss ACCURA CMM by testing positioning accuracy of magnetic joins the three popular probes: TP20 (Renishaw), VAST Gold (Zeiss) and VAST XXT (Zeiss).
XIX IMEKO World Congress
· TC14
· 2009
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Marco A. M. Cavaco, Mauro Eduardo Benedet, César A. A. Nogueira, Régis H. Coelho
One of the most applied procedures for detention of incipient faults in power transformers, such as partial discharges, electrical arcing and overheating, is the analysis of the concentration of gases dissolved in the isolating mineral oil. This analysis usually is carried through in a laboratory through chromatography in gaseous phase. Although it presents trustworthy results the chromatography brings some inconveniences as the need of a periodic sampling along with the distance from the laboratory to the substation of electric energy. There are some measurement systems available with the...
XIX IMEKO World Congress
· TC10
· 2009
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Carlos C. Dantas, Bruna G. M. Araújo, Valdemir A. dos Santos, Christine L. L. Finkler, Eric F. de Oliveira, Silvio B. Melo, M. Graça dos Santos
The results in single beam gamma transmission tomography are presented by an image processing based on the Algebraic Reconstruction Technique - ART. The mathematical reconstruction was carried out by Bezier triangles with Bernstein polynomials, and also by spline functions, and as a matter of comparison the Filtered Backprojection - FBP method was used. The image processing reconstructs the FCC (fluidized catalytic cracking) catalyst density distribution in an experimental riser. Typical problems are characterized as reconstruction models involve the inverse problem, basis function and...
XIX IMEKO World Congress
· TC7
· 2009
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Vasco Carvalho, F. Corrêa Alegria
A mobile station has been designed to monitor the air quality. Several of those stations are to be installed on the rooftop of taxis and buses in order to build a real time map of the air quality of a city. The modules are equipped with gas concentration measurement modules for 5 different gases (CO, NO 2 , O 3 , SO 2 , and CO 2 ), GPS receivers for localization, GSM/GPRS modules for communication and solar panels/batteries for completely autonomous operation. Here we describe in detail the choices made and the problems encountered in the design of the solar powering system for this mobile...
XIX IMEKO World Congress
· TC19
· 2009
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Artur Lopes Ribeiro, F. Corrêa Alegria, Octavian Postolache, Helena Geirinhas Ramos, M. Simões, J. Pimentel, P. Maurício, J. Calvário, A. Carvalho, T. Rocha
The use of Eddy currents is a well-known non-destructive technique used in the characterization of cracks in conductive non-magnetic materials. In this paper some experimental and finite element modelling tests with a new probe installed in a mouse pointer device connected to a PC are reported. This probe combines good sensitivity performances at low frequencies by using a giant magnetoresistor (GMR) magnetic sensor with an hand-held device capable of transferring easily its position to the PC.
XIX IMEKO World Congress
· TC4
· 2009
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G. Crotti, D. Giordano, A. Morando
This work illustrates an analysis of Rogowski coils for power applications, when operating under non ideal measurement conditions. The developed numerical model, validated by comparison with other methods and experiments, enables to investigate the effects of the geometrical and constructive parameters on the measurement behavior of the coil.
XIX IMEKO World Congress
· TC4
· 2009
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Christos L. Mitsas
The steady state data reconciliation problem is approached via a geometrical picture of its model and measurement abstract spaces. By completely utilizing the structure of the problem constraint matrix, via its singular value decomposition (SVD), data adjustment is accomplished and redundancy and observability conditions are formulated. As an example, the method is applied to a small network of liquid flowmeters in order to ascertain the reliability of the measurement results.
XIX IMEKO World Congress
· TC21
· 2009
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Shigeru Takayama, Yasutaka Nakajima, Riki Ohbayashi, Komyo Kariya
For monitoring natural landslide disaster, wireless sensing node network is so effective system. The sensing node is constructed by some sensors (acceleration, soil moisture, GPS and so on), data processing unit (micro processor) and wireless communication unit. The network topology we have constructed is mesh type. In the system, at sensing landslide, the node will transport the information to host system through the node network by using wireless communication. Generally, in natural field, the landslide is sensed as the changing of acceleration. But, it is so difficult to distinguish the...
XIX IMEKO World Congress
· TC19
· 2009
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