IMEKO Event Proceedings

Page 846 of 866 Results 8451 - 8460 of 8655

J. Gajda, R. Sroka

Traffic control requires measuring of road traffic parameters and vehicle parameters (velocity, length, number of vehicle, time distance between vehicles, etc.). One of very important parameters is the class of a vehicle. Up to date, videocamera systems, system with loop sensors, etc., have been used for classification. Unfortunately, the vehicle pattern were very complicated (picture from camera, time signal from loop, ...). Classification depends on the comparison of an actual signal to the reference pattern. It was very time-consuming and needed remembering the large reference pattern. This paper deals with a new method of vehicle classification. We have proposed the conversion of the measured signal into a vector of numerical parameters (only a few). The vehicle classification is being made by the comparison of such a very short vector with the vectors containing the values of parameters typical for the chosen class of a vehicle. Tests have been made on streets of Cracow (Poland). The classification efficiency for four predetermined vehicle classes is between 77% and 95%.

Septimiu Crisan, Ioan Gavril Tarnovan, Titus Eduard Crisan
Vein pattern recognition. Image enhancement and feature extraction algorithms

Vein pattern recognition is one of the newest biometric techniques researched today. While the concept behind the method is quite simple, there are various challenges to be found throughout the design and implementation of a vein scanning device concerning the hardware lighting system and the actual algorithms used for processing the acquired images. In order to keep the scanning errors to a minimum the image acquired from the camera should be almost noiseless and the algorithms should be able to detect the vein pattern in various real life conditions. Many implementations of this method are now in a commercial phase and there is a great need for a system that can detect, analyze and extract the correct human vein pattern while keeping a low cost and reducing the computational needs of the image processing algorithms. This paper will offer some hardware implementation solutions based on our research and different algorithms will be discussed.

Massimiliano Annoni, Marco Faifer, Loredana Cristaldi, Michele Norgia

The topic of water jet orifices efficiency and effectiveness evaluation has been considered in this paper. The performed analysis is based on the evaluation of the discharge, velocity and contraction coefficients for different water orifices. In order to overcome the difficulty to measure the water velocity at the orifice exit, which can reach 900 m/s in case of pure water jet applications (without abrasive additives), a suitable laser Doppler measurement system has been applied. An analysis of orifice performances is presented in the present paper, also considering the case of broken orifices, very important for industrial applications.

S. Ogata, K. Saza

We have improved a spatio-temporal correlation method to obtain velocity field from dynamic image. The new method can specify a certain image frame out of many sequential frames of a moving object and determine its 2-D velocity field on the basis of the specified frame. In addition, it enables us to avoid an edge effect of velocity field which appear at both ends of image row. The improvement has enhanced reliability and reduced computational time compared to other conventional methods.

M. L. Sanderson, R. H. Al-Rabeh

A method is reported here for the ultrasonic measurement of flow in boiler super-heater tubes. The tubes are in a tube bank formation running at high temperature (typically 300°C) and pressure (typically 100bar). To enhance heat transfer, the tubes in this application are ribbed internally with thick helical ribs. Further, all measurements have to be made on one side of the tube bank to avoid direct radiation on the fire side. Conventional ultrasound methods are difficult to apply in these conditions. The combination of thick steel walls, internal ribbing and the substantial temperature and density gradients do not provide for a well defined sound beam path. Instead a new method is proposed to measure the flow rate using the properties of the frequency spectrum of the noise imposed on the sound beam by random fluctuations in the velocity and density of the fluid caused by the nature of the flow in such tubes.
The measurement system consists of an ultrasonic beam generated using a conventional piezoelectric disc transducer/buffered from the hot boiler tubes by long threaded steel stalks which are bolted to a bracket welded to the tube bank. A second similar probe is fitted to receive the reflected sound beam signal. A resonant cavity is formed composed of the tubes, the water and the buffer rods. Envelop detection and frequency analysis is then applied to the received signal and the flow rate is deduced from the frequency contents of the noise spectrum. Such noise is caused by small changes to the effective path length of the sound beam caused by the temperature and density variations accompanying the flow. The received spectrum shows random components and its frequency content correlates well with the flow velocity.
A simple theoretical model in which the sound beam is assumed to be deflected by velocity and density variations is used to model the events leading to the observed results. Both laboratory and site measurements made during commissioning of a 300MW boiler are reported showing very similar behaviour when the frequency spectrum of the demodulated signal is considered. A similar observation applies to the frequency spectrum obtained from the theoretical model. A linear relationship is observed in all these cases between the flow velocity and the frequency content of the received signal- within the range of velocities considered. Further experimental and theoretical work is needed to cover a wider range of velocity and include effects of the internal ribbing and other factors not taken into the theoretical or the experimental treatment of the present work.

S. Bergeler, I. Menn, K. Michel

A new velocimeter for measurements in microscopic regions is presented. A common charge coupled device (CCD) has been used as spatial filter for one-component velocity measurements. The characteristics of this sensor are investigated and first application results presented.

Palau C V, Arregui F J, Palau G, Espert
Velocity Profile Effect on Woltman Water Meters Performance

This paper describes a detailed study, covering analytic as experimental aspects, about the effect on a commercial Woltman meter of different hydraulic fittings and configurations such as butterfly and gate valves. Firstly, a three-dimensional numerical simulation using computational fluid dynamics techniques (CFD) is used to calculate the alteration of the velocity profile by upstream fittings. Afterwards, the theoretical analysis undertakes the study of blade forces and torques generated by the fluid flow (Baker, 2000). Finally, laboratory test validates the analytical procedure proposed.

Štefica Celap

Consistency in analysis depends on being aware of a significant change in instrumental response, such as that caused by drift or changes in analytical precision, or both, and taking corrective action. The usual corrective action for drift is standardization. Standardization, however, when there is no real need, ca only broaden the spread of subsequent analyses. One purpose of this practice is to set guidelines that will avoid overstandardization. To control manufacturing processes, there must be confidence that a consistent material is being produced and that the analysis of the material is reliable. For assurance that the material meets specification, a purchaser may require the supporting record of control charts to assess that proper analytical control has been maintained.

Jean Mailhé, Jean-Marc Linares, Jean-Michel Sprauel

For the most part, metrology software is currently based on the measurement of distances or angles between geometrical elements. If this method of verification is well adapted to geometrical specification without a virtual state modifier, this is not appropriate for specification based on envelop zone such as in maximal matter condition, for example, for the ISO2692 standard. Usually the least squares best fit method is used to estimate derived surfaces, but the statistical information contained in the acquired coordinates remains under-used. The aim of this paper is to present a new approach for the verification of a part, based on a virtual gauge and using a statistical criterion.

Page 846 of 866 Results 8451 - 8460 of 8655