IMEKO Event Proceedings

Page 7 of 770 Results 61 - 70 of 7695

E. Lunca, C. Donciu, M. Cretu, A. Salceanu
A Basic Virtual Test System for EMI/RFI Problems

The paper presents a virtual system for locating and measuring near-field electromagnetic emissions in the frequency bandwidth from 100 kHz to 500 MHz. The implemented software controls the test equipment and performs both E and H-field strength measurements. The virtual system is not intended to verify compliance with international emission regulations. However, it is helpful in characterizing the abnormal electromagnetic fields and in extracting frequency and time domain information.

Marcel Reginatto, Andreas Zimbal
A BAYESIAN ANALYSIS TO EVALUATE THE NEUTRON RESPONSE OF A LIQUID SCINTILLATION SPECTROMETER

Many problems in neutron metrology require the determination of spectral neutron fluence rates. One of the prerequisites for doing spectrometry is the knowledge of the detector’s response function. We report on a method to determine the response function of liquid scintillation spectrometers given measurements in monoenergetic neutron fields. The response function is modelled using radial basis functions and the parameters of the model are chosen using Bayesian parameter estimation.

Shaochun Tang, Shubin Liu, Xinjun Hao, Weihao Wu, Lei Zhao, Qi An,
A BEAM PHASE AND ENERGY MEASUREMENT SYSTEM BASED ON DIRECT RF SIGNAL IQ UNDERSAMPLING TECHNOLOGY

A diagnostic system being designed to measure the beam phase and energy of the Drift Tube Linac (DTL) in the Proton Accelerator of China Spallation Neutron Source (CSNS) is described and the characterization of the prototype is presented. The signals received from Fast Current Transformers (FCTs) are Radio Frequency (RF) signals with the frequency up to 350 MHz and a dynamic range of -30 dBm to 3.5 dBm. The RF signals are converted to orthogonal streams directly with the In-phase and Quadrature-phase (IQ) undersampling technique based on high-speed high-resolution A/D conversion. Thus a high quality sampling clock system is indispensable. Two different clock systems are implemented and tested for comparison. All Digital Signal Processing (DSP) algorithms are implemented in one single FPGA, meanwhile a Nios II embedded system is also integrated in it for data transfer through the Ethernet. This system achieves a phase resolution better than 0.07 degree over the input signal amplitude range of -41 dBm to 7 dBm.

Hubert Zangl, Stefan Cermak, Bernhard Brandstätter, Gerald Gruber, Georg Brasseur
A BEM-APPROACH FOR SIMULATION AND OPTIMIZATION OF CAPACITIVE SENSOR TOPOLOGIES

In order to optimize front-end topologies of capacitive sensors precise knowledge of the coupling capacitances is important. These capacitances are not easily accessible by means of measurement without significantly altering them, and therefore a numeric method for determining them is advantageous. In this paper we use a Boundary element formulation for this task. Certain aspects of numerical accuracy of the formulation used are addressed. Results from simulations and optimizations are presented and compared with experimental results for validation of the approach.

Gustavo P. Ripper, Guillermo Silva-Pineda
A bilateral acceleration comparison between CENAM and INMETRO

A bilateral key comparison was conducted in the area of vibration between the National Institute of Metrology, Standardization and Industrial Quality (INMETRO), Brazil and the Centro Nacional de Metrología (CENAM), in Mexico; with INMETRO acting as pilot laboratory. This comparison was registered in the BIPM key comparison database (Mutual Recognition Arrangement - Appendix B) as SIM.AUV.V-K1.1 and the measurements were carried out by the participating laboratories from October 2004 to March 2006. The aim of this exercise was to compare primary interferometric measurements of complex charge sensitivity of standard accelerometers under sinusoidal linear accelerations in the frequency range from 10 Hz to 10 kHz. In addition, it was intended to provide a link between INMETRO and the key comparison reference values (KCRVs) established in the CIPM key comparison CCAUV.V-K1. This link of the regional metrology organization (RMO) key-comparison SIM.AUV.V-K1.1 to the International Committee for Weights and Measures (CIPM) key-comparison CCAUV.VK1 can be established because CENAM participated in both comparisons. Both participants used automated calibration systems based on homodyne quadrature laser interferometers to measure the sensitivity magnitude and the phase shift of two backto- back standard accelerometers in compliance with the international standard ISO 16063-11:1999.
The results reported by the participating laboratories at 30 specified frequencies and the respective calculated degrees of equivalence are presented. These results show an agreement better than 0,3 % from 10 Hz to 5 kHz and than 1% from 6 kHz to 10 kHz in sensitivity magnitude and better than 0,6D in phase shift in the entire frequency range.

Luca Callegaro, Jan Vejdelek
A Bridge for High-frequency Capacitance Scaling

A bridge, suitable for 1:1 and 10:1 ratio measurements of four terminal-pair impedances to frequencies up to 5 MHz, has been constructed and is presently under testing. The purpose of the bridge is to extend the Italian national standard of capacitance toward higher frequencies; however, the bridge will be employed for resistance comparisons also. Expected best uncertainty is in the order of a few parts in 10-5 for 10 nF - 1 nF ratio measurements, at 1 MHz.

Vadim Geurkov
A BUILT-IN SELF-CHECK METHOD FOR MULTI-CHANNEL MEASUREMENT SYSTEMS

Signature analysis techniques have become extremely popular in digital systems testing due to such advantages as simplicity, small amount of additional circuitry, and small degree of error masking. In this paper the signature analysis techniques are applied to mixed (analog-to-digital) systems testing. The general case of multi-channel measurement system is considered.

Andrzej Miekina, Roman Z. Morawski
A CALIBRATION METHOD, BASED ON RIDGE LS ESTIMATOR DESIGNED FOR DETERMINATION OF OLIVE OIL MIXTURES ON THE BASIS OF NIR SPECTRAL DATA

The spectrophotometric analysis of oil mixtures, containing olive oil, is the subject of this paper. Its objective is to propose and evaluate a new methodology for determination of a selected component of such a mixture. According to this methodology, the space of concentration values to be estimated is partitioned into subspaces and the calibration is performed separately for each subspace by means of a new piecewise ridge least-squares estimator. The estimation of concentrations is carried out, using the results of calibration, in two cycles: first, rough estimates of concentrations are found and a corresponding subspace is identified; next, the results of calibration, obtained for this subspace, are used for refining the estimates of concentrations. The performance of the proposed methodology is assessed using a criterion related to measurement uncertainty.

T. Dunker, S. Sperling
A CALIBRATION STRATEGY FOR SYSTEMS WITH 2-D LASER SENSORS

We consider measuring machines (MMs), which use one ore more 2-D laser sensors (2-DLSs) for automated dimensional inspection. In order to transform several measurements from their sensor coordinate frame (CF) into a world or object CF, we need a parameterized model of these transformations. We present a method, which allows for very different MMs to set up a model, to construct a calibration object and to estimate the model parameter from measurements on the calibration object.

C. Hirunyapruk, P. Rattanangkul, B. Thummawut, V. Plangsangmas
A CALIBRATION SYSTEM FOR LASER VIBROMETERS AT NIMT

Laser Vibrometers have been used in many applications such as automotive and hard disk drive industries. In metrological field, laser vibrometers are employed as reference standards for the calibration of accelerometers. To have the traceability chain to the International System of Units (SI), several National metrological institutes (NMIs) and companies have developed calibration systems for laser vibrometers. National Institute of Metrology (Thailand), NIMT, is one of those NMIs. This paper describes the set-up for the primary vibrometer calibration system used at NIMT and presents the methods used according to methods 1 and 2 shown in the international standard ISO16063-41. The calibration results are also discussed.

Page 7 of 770 Results 61 - 70 of 7695