9762 papers found
A comparative analysis of induction and electronic meters with regards to active energy measurements is presented, based on results obtained by application of a designed plan involving several input factors such as power voltage amplitude, power frequency, voltage total harmonic distortion (THD) and flicker severity.
The increase number of high speed trains needs an high reliable and available railway overhead line. Because of the elevated train speed increases the wear failures, with possible railway track interruptions. Therefore it’s necessary to identify failures modes and correlated effects to improve the railway network availability and safety features as well as maintenance and renewal costs. This strictly depend on the appropriate use of diagnostic methodologies: the traditional approach of cyclic maintenance needs to be replaced by more efficient approaches, such as on-condition and predictive...
The project proposes accomplishing of a new informatics system architecture, under the form of a high-speed virtual laboratory, with a multitask type access on laboratory work, to remove users’ waiting lists and allow reconfiguration of electric assembling in real time. Accomplishing the project was preceded by a thoroughly analysis of didactic requests according to economic problems, so that, the following aspects would be solved: Students will access from the distance real instruments and will accomplish online test montages, in the idea of understanding all the aspects of a real...
In this paper a new approach is proposed, for the detection of harmonic sources in polluted power systems. It is a single-point strategy, based on a comparison among different “nonactive” power quantities proposed in literature, that, in the same working conditions, assume different values at the metering section. Some simulations tests were carried out on a standard IEEE test system, proposed, by other authors, as a benchmark system for the analysis of multi-point measurement techniques for harmonic pollution monitoring. The obtained results show that the proposed single point approach is...
This work proposes a virtual instrument (VI) for the electric power quality monitoring aiming to act in real-time for detecting, monitoring and recording all typical disturbances superimposed on the ideal signal; it is based on both IEC standards 61000-4-30 and 61000-4-7 [1] [2] and on the directive for the Consultation of the Italian Authority for the Electric Power and Gas of April 6, 2005. The latter presents the peculiar features of an experimental monitoring system for the mid voltage electric energy distribution network whose experimentation should lead the distributing companies to...
Calibration of electrical energy meters (EEM) is coming up as a metrological concern. Latest EU directives, about measuring instruments adopted for commercial transactions, state that their accuracy must be verified in actual operating conditions. This requirement is leading all laboratories involved in EEM calibration in serious difficulty because this kind of metrological verification is, at the moment, still not fully developed or even clarified. In this paper a proper automated measurement station able to perform calibration, also on-site, is presented, the compensation techniques for...
The accuracy of the hole-drilling strain-gage technique, the most widely used method for residual stress measurement, is directly related to: 1) the eccentricity between the hole center and rosette center, respectively, and 2) the accuracy of corrections for integration tendency of the strain gages. Although the drilling tool is optically aligned, the eccentricity always can not be zero and it is a source of error, affecting the accuracy of this technique. An equation for correction of the data affected by hole eccentricity has been proposed by A. Ajovalasit, but it is not precise enough,...
The Maximum Entropy probability density function associated with the testable information on the range and the first and second order moments of the random quantity of interest is derived. The validity of such approach is experimentally demonstrated through comparison between the proposed maximum entropy distribution and the U-shaped distribution. The underlying physical assumptions which must be satisfied for the proper use of the U-shaped distribution are revisited in the context of wide-band applications, such as Electromagnetic Compatibility measurements.
A web-based system used in olfactory illness patients at home and their physician was developed. A web browser plug-in simplifies the process of capturing virtual odours and transferring it to a web site for novice computer users. The design of the virtual odours capture plug-in can be reused to acquire and securely transfer any type of data over the web. For example, readings samples from Web-E-Nose device, which can be connected directly to the Internet, can be transferred to a home E- Medicine web site. Both patients and doctors can access this web site.
A key role of metrology in the realization of the concept of sustainable development of the regions and countries of the world, is underlined. In particular, are those developing regions/countries and those in the process of an economical transformation in their economic systems. The most important influence of the measurement process validation in all kinds of conformity assessment systems, is explained. The need for the creation of regional metrological centres and information systems to aid the measurement process validation for different testing and calibration laboratories, are pointed...