IMEKO Event Proceedings

Page 789 of 855 Results 7881 - 7890 of 8545

Lars Buettner, Christian Bayer, Katsuaki Shirai, Andreas Voigt, Juergen Czarske

We report about a novel laser Doppler field sensor, which is capable of measuring the three-component (3C) velocity field in fluid flows in a twodimensional area (2D) without mechanical scanning and without using a camera. The sensor is based on laser Doppler velocimetry but employs four superposed fan-like interference fringe systems. A spatial resolution in the sub-micrometer range can be achieved enabling highly spatially resolved flow studies. Possible applications are investigations in micro-fluidics or precision flux measurements.

S. Z. Zahwi, A. Mekawi
Three dimensional (3D) surface measurements based on (2D) stylus instrument

Three dimensional measurements (3D) of surface topography are increasingly being recognized as the most adequate method for obtaining a better understanding of surfaces. The dimensional and surface metrology department at the National Institute for Standards in Egypt (NIS) developed a computer-controlled system for 3D surface measurements. The developed system is based on a 2D surface measuring instrument using a stylus contact method. A positioning table is used to displace the specimen underneath the stylus in a cross direction to the traverse stroke. The system can scan small areas on the measured surface (5.6 mm × 0.56 mm) by traversing the stylus of the measuring instrument over the surface in parallel traces. The system consists of a “Talysurf 10” stylus surface measuring instrument interfaced to an “IBM” compatible PC computer with a data acquisition device (DAQ). The (DAQ) is used to control the movement of the measuring stroke of the pick up in the X – axis, to control the movement of the positioning table in a cross direction to the stroke as Y- axis, and to take the data of each profile from the stylus vertical movements during the measurement stroke as Z-axis.
The software for the mentioned controls is made using “Labview” programming language. All data of the 3D surface are taken using unfiltered skid less mode of operation. A “Matlab” software is developed and used to take out the trend of the surface using a least square surface plane, then an approximation of a Gaussian filter (moving average) is used to filter the data. A software to analyze the data to get the 3D surface parameters and functions is also developed.

Chu-Shik Kang, Jae Wan Kim, Jong-Ahn Kim, Tae Bong Eom

A new method of three-dimensional profile measurement of four-step reference specimens is presented. Instead of measuring only the height difference between central points of the two neighbouring surfaces of the specimen, overall profile of the whole specimen can be measured by using the fringe scanning Fourier transform method. The method to determine step height from its surface profile is proposed.

Qinghua Wang, Hiroshi Tsuda, Satoshi Kishimoto, Yoshihisa Tanaka, Yutaka Kagawa

Three Moiré techniques based on a laser scanning microscope (LSM) were presented and compared for the first time, including the LSM scanning moiré method, our developed LSM overlapping moiré method, and our newly developed LSM secondary moiré method. The formation principles of these moiré patterns and the measurement principles for deformation measurement were introduced. The applicable conditions of these three techniques were analyzed. Some typical moiré fringes on a strain gauge, carbon fiber reinforce plastics, a polyimide film and a silicon wafer were illustrated. Our developed LSM overlapping moiré method and secondary moiré method are effective in eliminating the scanning distortion of the LSM. These three kinds of moiré techniques are able to expand the application range of the LSM in deformation measurement at the micron and the submicron scales.

Pierre Otal, Jean-Claude Legras
Three technologies met in the absolute pressure range 0,5 Pa to 3 Pa

The LNE standards around 1 Pa absolute are constituted by a force-balanced piston gauge (FPG), 100 Pa capacitance diaphragm gauges (CDGs), and spinning rotor gauges (SRGs). The key parameters limiting the performance of the devices are presented. The results of a comparison involving at the same time the three instruments are presented and discussed, as well as the capabilities of these instruments in this range. As an example, the repeatability of measurements, and the linearity error in the comparison are less than 2 mPa.

Chenguang Cai, Zhihua Liu, Ming Yang
Three-Component Primary Vibration Calibration System at NIM

A three-component primary vibration calibration system had been set up in National Institute of Metrology, which consists of an air bearing three- component shaker, a sinusoidal three-component control system and a primary three-component vibration measuring system. A motion coupling device based on air bearing force transferring and motion guiding has been developed to simultaneously generate three-component vibration in the three orthogonal coordinates. The rectilinear, circular, and elliptical space motions have been realized by the sinusoidal three-component control algorithm. The three-component measuring system can simultaneously measure the three orthogonal motion quantities based on sine-approximation method.

M. Henry, M. Tombs, F. Zhou, M. Zamora

This paper describes a new three-phase flow metering technology, combining Coriolis mass flow and water cut readings and without applying any phase separation. The system has undergone formal laboratory trials at NEL, UK and at VNIIR, Kazan, Russia; a number of field trials have taken place in Russia. Results from the NEL trial will be described in detail. Initial experiences from field trials will also be described. Together, these results demonstrate the potential for using Coriolis mass flow metering combined with water cut metering for three-phase (oil/water/gas) measurement.

Nadia Mammone, Aime’ Lay-Ekuakille, Patrizia Vergallo, Francesco C. Morabito

Electroencephalography (EEG) is a well established methodology to record the electrical activity of the brain. We can be interested in monitoring the cerebral electrical activity for different purposes: studying the cognitive activity, interfacing the brain with the machine, extracting diagnostic information, etc. Artifacts are unwelcome signals, generated by electromagnetic sources not related to cerebral activity, that may overlap to the EEG signals and affect their processing. Whatever the goal of EEG processing, a preprocessing step consisting in artifact removal is normally required. Unfortunately, artifact removal is unavoidably a lossy procedure, therefore, the goal must be removing artifacts losing the minimum amount of useful information embedded in the EEG. To this purpose, Automatic Wavelet-ICA was recently proposed by the authors. The technique is multistep and parameter dependent, thus its performance may vary signi?cantly with the parameter setting. The present paper shows the results of the optimization with respect to the threshold used for artifact detection.

Fernando M. Janeiro, Pedro M. Ramos
Threshold estimation in least-squares error functions: Application to impedance spectroscopy

Least-squares error functions are widely used in the determination of the parameters of models of a system. When this procedure is iterative, the problem of deciding when to stop iterating arises. Usually a threshold is defined, so that when the error function falls below this value, the least-squares error procedure can be stopped and the solution is found. However, this threshold depends on the uncertainty of the measurements. In this paper, the cost function PDF (probability density function) is analyzed to obtain a closed-form expression for the estimation of this threshold, in the framework of impedance spectroscopy.

Andrea Taschin, Paolo Bartolini, Jordanka Tassaneva, Jana Striofa, Raffaella Fontana, Cristiano Riminesi, Renato Torre
THz time-domain spectroscopy: investigation of thin layers of inks

We develop an original experimental procedure and a comprehensive method of data analysis to measure the optical parameters of drawing media in the THz spectral range. The method based on the THz – Time Domain Spectroscopy is applied to recover material parameters on drawing inks deposited on polyethylene pellicles with thicknesses down to tens of micrometers. In particular, we investigated three commercial inks: a red ink (based on cochineal carmine), a blue ink (indigo) and a black ink (irongall). The implemented experimental procedure and numerical method enable us to extract the absorption coefficient and refractive index spectra in an absolute scale, opening the possibility to investigate the material parameters in the THz range with a complete quantitative study.

Page 789 of 855 Results 7881 - 7890 of 8545