IMEKO Event Proceedings

Page 784 of 855 Results 7831 - 7840 of 8545

Z. Malec
THE VIBRATION OF CONTACTS OF AN ELECTROMAGNETIC RELAY

The article deals the vibration of contacts of electro-mechanical relays (and mechanical contacts generally), its properties, its measurement and a special measuring instrument built for this purpose.
The vibration of contacts is caused by ringing of the springs (and other mechanical components) carrying the contacts. It generates quasiperiodic interruptions of current flowing through a moving contact-pair. These interruptions cause problems e.g. when this current controls fast semiconductor circuits or when the contact-pair is loaded by a remarkable current and sparks and burning of contacts comes in. To avoid these problems some linear or nonlinear filters must be introduced. The measurement of this phenomena has shown that the vibrations mentioned here affect remarkably the time parameters (different delays) describing the behavior of the relay and that these parameters become to be random. The statistical characteristics of these parameters contain information about the technical (diagnostic) state of the relay, which is important for estimation of the behavior of the relay in future. Finally, the basic data of the measuring instrument are introduced.

Aldo Arriaga, Marcos Arroyo, Norma Pérez
The Virtual Drilling Crew

Submarine geotechnical exploration is a challenging task that is currently undergoing a paradigm change thanks to robotics and teleoperation. The MD500 Project is an underwater subsea geotechnical drilling and in situ testing device designed to sample and probe up to 150 m of soils of rock beneath the seabed in water depths of up to 500 m. The system has applications in several areas of marine activity, such as port infrastructure, nearshore and offshore renewable energy projects, oil & gas, submarine mining, etc. The machine consists of a group of devices operated remotely and that must synchronize with each other: drilling tower, stabilizing legs and three manipulators (two cartesian and one anthropomorphic). These manipulators can be operated manually or in a semi-automated (robot) mode. The automated routines aim to substitute the actions of the drilling crew when handling the tubes and rods in the harsh environment for which the machine is envisioned The paper presents an overview of the code and logic behind the tool manipulation and handling routines of the MD500, which are at the core of a “Virtual Drilling Crew” inbuilt in the machine design.

Romuald Masnicki, Janusz Mindykowski
THE VIRTUAL INSTRUMENT BASED ON THE ZIGBEE NETWORK

In this paper, some remarks concerning cable as well as wireless connections in measurement channel are inserted. The demonstration application managing wireless network was shortly described. The main focus of paper is placed in the recognizing of the data acquisition protocols used in demo application for data transfer from wireless network to PC. The implementation of wireless sensor network to the virtual instrument under LabVIEW environment is presented.

Di Angelo L., Di Stefano P, Fasciani R., Gaudenzi D., Pane C.
The Virtual Reconstruction of the Lake Fucino's Emissary

The Lake Fucino's emissary represents one of the most important hydraulic construction realized in antiquity. Unfortunately, little remains of the original structure of the Roman emissary, obliterated by the Torlonia building and the definitive drying of the lake. This article presents its virtual reconstruction, in order to understand survey and technological issues met by Romans and to visually offer reconstruction theories, interpreting a partially lost evidence of the Roman technology. The engineering resource becomes the means for a deeper comprehension of archaeological questions, combining the tools of engineering and archeology.

F. Castelli, M. Faifer
The Voltage to Frequency Converter Using as Reference the Pull-In Voltage of a Reed Relay

The chief requirements of basic components of digital systems for industry are both the availability of preventive maintenance and high reliability. Integrated semiconductor components are highly lacking in both these requirements. To respond to the referred exigencies a voltage to frequency converter (VFC) by the use of a reed relay (RR) and a charge-discharge method with as reference the pull-in voltage of RR is illustrated. Test results prove a high linearity and that it is imperious to environmental temperature and proper for extreme environmental industrial conditions.

Raffaele Persico, Giovanni Leucci, Sebastiano D Amico, Lara De Giorgi, Emanuele Colica, Maurizio Lazzari
The watch towers in Malta: a patrimony to preserve for the future

In this contribution we will focus on some results achieved within the international bilateral project Non-invasive investigations to enhance the knowledge and the enjoyment of cultural heritage (funded by the Italian National Research Council and by the University of Malta). In particular, we will focus on some GPR and geoelectrical investigations performed on the so called Red Tower and on the so called White Tower, both on the western side of the island of Malta.

Vaidotas Gegevicius
THE WAYS TO REALISE NATIONAL MASS STANDARD OF SMALL COUNTRY IN 3RD MILLENIUM

The metrological requirements for the mass determination in regard to balances, weights and weighting are discussed, and achievable uncertainties in weightings in the laboratory and in actual practice given.The presentation describes a present situation in mass measurements in Lithuania and provides a technical specification for the establishment of Lithuanian state measurement standard of the mass unit.

Lan Qiu, Xuewei Wang, Jing Wang
The Whole-system Model of Smart Electricity Meter

In order to analyze the error effect of smart electricity meter under different dynamic load current fluctuation and evaluate the errors of smart electricity meter. At first, the models of four units in smart electricity meter are established based on their mechanism, which include voltage channel model, current channel model with a programmable gain amplifier (PGA), active power measurement model and energy measurement model. Secondly, the whole-system model of smart electricity meter is established base on above four models to reflect the inside ralations causing dynamic errors. Finally, a dynamic error testing system is built to test the dynamic errors of the typical electricity meter, and the correctness of the whole-system model is verified by comparing the measured dynamic errors and simulation errors. The result shows that the whole-system model can be used to evaluate the errors affected by the complicated load current fluctuation.

Francesco Righini
THE WORLD OF SUBSECOND THERMOPHYSICS

The measurement techniques developed in the last thirty-five years for the accurate measurement of thermophysical properties at high temperatures (800-3700 K) using subsecond current-heating are reviewed. Only experiments of total duration around 1 s are considered, with data acquisition performed at the sub-millisecond level. Emphasis is placed on the physics of the different techniques, as developed in major national measurement institutes around the world. A complete survey is provided, covering multiproperty experiments, extensions to thermal expansion and thermal conductivity and measurements at the melting point. An intercomparison of experimental results available in the literature provides an indirect evaluation of the validity of these techniques.

Franco Castelli
THE ZERO-FLUX CURRENT TRANSFORMER TO IMPROVING ACCURACY WITH APPLICATIONS FOR DISTORTED WAVEFORMS AND DC BIAS

Current measurements on electrical power systems very often concern nonsinusoidal conditions, due to the presence of distorting loads connected to the network (typically because of the presence of power electronic components) and the consequent harmonic pollution. In addition the presence of DC components, superimposed to alternating ones can make it impossible to correctly use the current transformers (CT’s) and gives rise to the burden and composed (namely due to the distorted waveforms) errors, that are arising from the presence of the core flux in CT. Moreover saturation, hysteresis, and polarization are supported by the core flux. The presence of the core flux is the difference between a real CT and an ideal one.

Page 784 of 855 Results 7831 - 7840 of 8545