IMEKO Event Proceedings

Page 8 of 855 Results 71 - 80 of 8545

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 MetrologĂ­a (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.

Giuseppe Schirripa Spagnolo, Lorenzo Cozzella, Fabio Leccese
A Brief Survey on Underwater Optical Wireless Communications

Acoustic, radio frequency (RF) and optical waves systems are the technologies that are used to carry out underwater wireless communications. In scientific, military and industrial sectors, the development of robust and efficient submarine wireless communication links is of enormous interest. To achieve secure short-range wireless communications, the Underwater Optical Wireless Communication (UOWC), which uses the 450-550 nm spectral range of the electromagnetic spectrum, is a good technology. Recently, UOWC applications have been proposed for environmental monitoring, offshore exploration, and military operations. There are many review articles published on this topic. However, research in this field evolves rapidly as does existing literature. The article deals with current and potentially available UWOC technologies in the near future. It is aimed at those who want to undertake studies in this field. Obviously, this paper does not attempt to cover every single aspect of UWOC.

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.

G. Kok, N. Pelevic, A. Chiribiri, X. Milidonis, M. Nazir, M. Capstick, S. Drost, C. Poelma, T. Schaeffter
A calibrated physical flow standard for medical perfusion imaging

In the medical sector, various imaging methodologies or modalities (e.g. MRI, PET, CT) are used to assess the health of various parts of the bodies of patients. One such investigation is the blood flow or perfusion of the heart muscle, expressed as the (blood) flow rate normalized by the mass of the volume of interest, with unit mL/min/g. Currently there is no physical flow standard for the assessment and validation of myocardial perfusion imaging methodologies, resulting in a large proportion of medical diagnoses being inaccurate and highly dependent on the scanner type, software used and the clinical operator. In the EMPIR 15HLT05 PerfusImaging project a phantom simulating myocardial perfusion has recently been developed with which imaging modalities can be tested. In this paper the construction and validation of the phantom is described which involved several iterations with design updates, computational fluid dynamics simulations, 3D printing of the phantom, ultrasound imaging velocimetry and magnetic resonance imaging (MRI). Dynamic contrastenhanced MRI was performed to image the passage of a tracer through the phantom and estimate perfusion. Two flow models and associated data analysis methods to relate the measurement data with the reference flow rates are presented and discussed.

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 8 of 855 Results 71 - 80 of 8545