IMEKO Event Proceedings

Page 791 of 822 Results 7901 - 7910 of 8218

Paul Roberts
UNDERSTANDING SPECTRUM ANALYZER CALIBRATION

Calibrating a Spectrum Analyzer usually involves a variety of measurements, with each requiring a suitable input signal. A typical procedure generally utilizes a number of signal generators together with other pieces of equipment to generate the signals and ensure their accuracy. This paper provides an overview of spectrum analyzer calibration with discussion of the most common calibration tests, their signal requirements, and approaches for meeting those requirements.

Peppe J. V. D’Aranno, Francesca Gizzi, Maria Marsella, Silvia Scifoni, Marianna Scutti, Alberico Sonnessa, Manuela Bonano, Michele Manunta
Understanding the effects of tunneling on buildings by analyzing DInSAR data: the case of the new subway in Rome, Italy

Monitoring the displacements of the buildings during the execution of underground works is a very demanding activity in large urban areas contexts, due to the number of structures involved and to the duration of the measurements throughout the realization time. Therefore, the surface deformation detection cannot be based on direct measurements using ground-based sensors, only, and should include technologies that allow a systematic and comprehensive monitoring. The satellite DInSAR technique (Differential Interferometry Synthetic Aperture Radar) provides displacement time series of a large number of measuring points, which can be associated with different portions of a building and are able to reveal differential settlements. Furthermore, the availability of SAR data archived since 1992 allows performing back analyses to evaluate also long-term settlement processes not directly linked to the tunneling works. More recently, the COSMO-SkyMed constellation, developed by the Italian Space Agency (ASI), has provided data at higher space/time resolution, which have been profitably used to detect and follow the evolution of the settlements caused by tunneling excavation works, as in the case of the new metro line in Rome. By applying the advanced DInSAR methodology, we have estimated average rates of displacement for a number of buildings over the Metro C track interested by the subsidence, very likely triggered by tunneling. A classification-based approach was applied by taking into account the displacement rates and the associated statistical error parameters. This provided a tool for the direct identification of the most critical buildings that need further investigations.

S. Buogo, S. Mauro, J.F. Borsani, S. Curcuruto, A. Biber, A.C. Çorakçi, A. Golick, S. Robinson, G. Hayman, S. Barrera-Figueroa, M. Linné, P. Sigray, P. Davidsson
Underwater acoustic calibration standards for frequencies below 1 kHz: current status of EMPIR "UNAC-LOW" project

"UNAC-LOW" is an ongoing project under EURAMET's EMPIR programme whose aim is to develop the European metrological capacity in underwater acoustics for the calibration of hydrophones and autonomous noise recording systems for frequencies below 1 kHz. The project will provide an improved framework to underpin the absolute measurement of underwater sound in support of regulation and EU Directives for which traceability is currently lacking. Methods for the calibration of hydrophones and autonomous recording systems in the frequency range from 20 Hz to 1 kHz will be developed and validated by comparison measurements between the project partners. Longterm operation of the calibration capabilities will be ensured by each partner, to provide a coherent metrology strategy for Europe within this field. Current activities regarding the design and preparation of calibration setup are here described, in view of round-robin calibrations and validation scheduled for year 2018.

Enrico Petritoli, Fabio Leccese, Marco Cagnetti
Underwater Gliders: Mission Profiles and Utilisation Strategies in the Mediterranean Sea

The final aim of this paper is to create peculiar strategies in order to optimise the use platform for underwater scientific research that can accommodate a wide range of different payloads. The main mission profiles and the related employment strategies are optimized, according to the dedicated environment: we will examine in detail the three types of typical mission (pure drift, corrected drift and glider) finally a hybrid one (Jellyfish).

Rachele Napolitano, Paolo Chiariotti, Enrico Primo Tomasini
Underwater Image Pre-Processing for Photogrammetric Application

This work describes a new method for correcting underwater images acquired under natural illumination condition and targeted to photogrammetry for 3D object reconstruction. In particular, a comparison between the new approach and a previous one from literature is presented. The new approach demonstrated to be a feasible and robust solution to improve quality, colour and contrast in underwater imaging by means of a three-step procedure. The focus of the paper is on 3D reconstruction of small-sized corals in shallow water. The colour of pre-processed images, with a visible green-blue colour cast, are enhanced and the higher images quality eases the whole object reconstruction acquired in a poor visible scene. The higher performance of the proposed method is experimentally demonstrated.

G.A. Kyriazis, R.T.B. Vasconcellos, J. Melcher
UNEQUALIZED CURRENTS IN TWO TERMINAL-PAIR COAXIAL CAPACITANCE BRIDGES

It is necessary to maintain conditions of zero net currents in the cables of ac coaxial bridges. Current equalizers are used for dealing with this problem. It is shown here how they were applied in the construction of a two terminal-pair capacitance bridge with an uncertainty of about one part in 108.

Octavian Postolache, Artur Lopes Ribeiro,Helena Ramos
UNIFORM EDDY CURRENT PROBE IMPLEMENTATION USING PLANAR EXCITATION COIL AND GMR SENSOR ARRAY

Defect detection in conductive plates represents an important issue. This work presents designed and implemented uniform eddy current probe architecture (UECP) that includes a planar excitation coil and a GMR magnetometer sensor array as part of a non-destructive testing (NDT) system developed using a virtual instrument system technology. The usage of GMR sensors provides frequency independent sensitivity to the UECP, assuring speed, depth, and higher resolution in eddy-current testing, while the usage of a set of GMR sensors allows rapid scanning of an area for defects in a single pass.
A practical approach concerning the UECP design, implementation and experimental results obtained on cracks detection machined in aluminum plates for a single or multiple GMR sensor usage as main parts of UECP are presented. Experimental results regarding the usage of the novel eddy current probe to detect induced flaws in aluminum plates are included in the paper.

M. P. van der Beek, I. J. Landheer, B. Mickan, R. Kramer, D. Dopheide
UNIT OF VOLUME FOR NATURAL GAS AT OPERATIONAL CONDITIONS, PTB AND NMi VSL DISSEMINATE "HARMONIZED REFERENCE VALUES"

Since November 1999, PTB and NMi VSL have established and disseminate Harmonized Reference Values for the Unit of Volume of Natural Gas. These Reference Values for Natural Gas at operational conditions are applied, not only in the test facilities at which they originate but are installed and applied as well in other test-facilities and have a wide application in Custody Transfer Measurements. The paper describes backgrounds and procedures that have been developed and that are currently in use in Germany and The Netherlands. The prerequisites of the harmonization process, the underlying procedures, results obtained so far as well as the economic benefits for the European market will be pointed out. The "harmonization" can be considered as the first factual step towards the realization of a European unit of volume for Natural Gas at operational conditions.

Jerzy Hoja, Michal Kowalewski, Grzegorz Lentka
Universal Laboratory Measurement System for Evaluation of the Impedance Spectroscopy Method Based on Multi-harmonic Excitation Signal

The paper presents universal laboratory measurement system for evaluation of the impedance spectroscopy method based on multi-harmonic excitation signal. The system is mainly designed to optimise the method for impedance spectrum digital measurement dedicated to implement in low-cost portable instrument oriented for diagnostics of technical objects located in the field. Due to time constraints during field measurements, it is important to shorten acquisition time of impedance spectrum by using multi-harmonic excitation. Implementation of the method in the field-worthy instrument requires optimisation procedures in terms of hardware complexity and power consumption requirements minimisation. The results of simulation tests as well as experimental verification were presented.

R. Kochan, A. Sachenko, V. Kochan, N. Vasylkiv
UNIVERSAL SIGMA-DELTA ADC FOR INTELLIGENT DISTRIBUTED INSTRUMENTATION

In this papers the precision single-board, 8 channels, 24 bit sigma-delta ADC with on-line remote reprogramming mode is described. The results of experimental researches of the noise immunity of the developed ADC in real (industrial) measurement conditions are presented. The results of experimental researches of the prototype in the same measurement conditions are also considered.

Page 791 of 822 Results 7901 - 7910 of 8218