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Pavel Macura, František Fojtík, Radomír Hrncár
EXPERIMENTAL RESIDUAL STRESS ANALYSIS OF WELDED BALL VALVE

The paper is devoted to the issues of experimental analysis of residual stresses on the concrete part of pipelines – welded ball valve. A semi-destructive hole-drilling method was used for measurement, and experimental stress analysis and evaluation of residual stresses was made in accordance with the US standard ASTM E 837 – 01, as well as with use of an integral method. Residual stresses were measured both immediately after welding and after pressurising of the ball valve. This has enabled observation of the influence of pressurising on change of residual stresses in the neighbourhood of the welded joint. Results of measurement of residual stresses served for further assessment of strength and service life of this component.

Sheroz Khan, A. H. M. Zahirul Alam, Zuraidah Zainudin, Muzna S. Khan, Shihab Abdel Hameed, Aisha Hassan Abdalla, Mohd. Rafiqul Islam
MULTIVARIABLE TRANSDUCER INTERFACING CIRCUIT FOR WIRELESS MONITORING OF SMART IMPLANTS

The increasing use of microprocessors and microcontrollers in measurement and data acquisition systems has necessitated the need for obtaining sensor response in a digital format, thus avoiding the need for an analog-to-digital conversion stage. Further, in quite of a number of automation applications, there is the need of wireless transmission of data signals over narrow gaps. The signal obtained is loaded with data from transducers measuring parameters of interest for monitoring or other reasons. Changes in resistive sensors as a result of parameters changes are obtained as a digital signal with its time-period, amplitude and duty cycle directly proportional to variations in three different resistors. This is one useful way of reading data signals from more than a single sensors at the same time by using a measurement circuit with a single output signal. The utility of this work lies in applications where the allowable room for proper wiring is either impossible or the congestion of wiring is be avoided for more clarity and better automation. The experimental results obtained in this paper match with the simulation details of the interface circuit.

Apostolos Psyllos, Christos Anagnostopoulos, Eleftherios Kayafas
SIFT-BASED MEASUREMENTS FOR VEHICLE MODEL RECOGNITION

A SIFT-based Vehicle Manufacturer and Model Recognition (VMMR) method was utilized to tackle the problem of vehicle security. Distinctive parts of the vehicle frontal view such as the headlights, grill and logo area were segmented. A series of experiments were conducted in a variety of outdoor conditions, where a query image that was rotated, scaled, shifted or set in different lighting conditions, matched against a database of model images. In this work, is shown that image processing functions based on Scale Invariant Feature Transform (SIFT) measurements can be used to obtain high performance object features recognition, creating a keypoint fingerprint (pattern) for each image class. In the majority of the cases, SIFT method performs very well, in terms of efficiency and robustness.

Mussa Bshara, Leo Van Biesen
AVAILABLE MEASUREMENTS IN CURRENT WIMAX NETWORKS AND POSITIONING OPPORTUNITIES

In this paper, we consider the practical issues related to positioning in WiMAX networks depending on the available measurements. The network under study is the Clearwire network deployed in Brussels capitol city. The focus lies on making the available terminal-based measurements, study the possibility of using these measurements in positioning and provide a comparison between these measurements depending on the accuracy achieved and the difficulty to obtain them.

Tassanai Sanponpute, Apichaya Meesaplak
VIBRATION EFFECT ON ROCKWELL SCALE C HARDNESS MEASUREMENT

Three ranges of Rockwell scale C reference hardness blocks: 20, 40, and 60 HRC were measured by deadweight-lever system hardness testing machine with two types of display: analog and digital. The testing machines were placed on the vibration table, whose frequency and amplitude of vibration can be controlled. Piezoelectric probe and vibration meter were used to confirm both amplitude and frequency of vibration. The hardness value at free from vibration is used as a reference to calculate the error of each hardness measurement at certain frequency and amplitude. Both machines give the same tendency. At vibration frequency higher than 15 Hz, there is no significant error of measurement in any vibration amplitude lower than 0.04 m/s² for all three hardness ranges. However, below 15 Hz vibration frequency, the negative error of both digital and analog displayed machine appears significantly higher and increases as the amplitude of vibration increases. Moreover, the softer range of hardness is more affected by the vibration. . Therefore, the result from this paper can be used as guideline for laboratory to control environmental vibration amplitude to be less than 0.01 m/s² for frequency (10 ± 5) Hz and 0.05 m/s² for other in Rockwell scale C hardness measurement.

Grzegorz L. Pankanin, Artur Kulinczak
DETERMINATION OF VORTEX CONVECTION VELOCITY WITH APPLICATION OF FLOW VISUALIZATION AND IMAGE PROCESSING

The paper is related to von Karman vortex shedding phenomenon being the basis of the vortex flow meter design. The vortex convection velocity belongs to the problems rather rarely touched on in papers and articles. But its recognition can improve our knowledge concerned the applied phenomenon and finally help in its better understanding. Due to the flow visualization supported by the image processing, tracking of the vortices is feasible. Finally, the convection velocity can be calculated and its changeability along the pipe axis can be evaluated.

Edi Kulderknup, Jürgen Riim, Tuuli Levandi
UNCERTAINTY OF ROAD TRAFFIC SAFETY MEASUREMENTS

Road traffic has important part for the every days life. Traffic accidents are related to the vehicles technical side and to the traffic surveillance from authorities and police. Environment is damaged mainly through vehicles exhaust gases, noise and vibration. This study work deals with road traffic safety measurements uncertainties. Damages can be minimised if uncertainties of the measurements are estimated and taken into account by above areas. In this work will be given models of uncertainty estimation for the vehicles technical conditions measurements, environment safety measurements and authorities surveillance measurements. Estimated and validated are concrete values of the uncertainties for various situations using measurement comparison data.

Valter C. Rosa, Amauri Oliveira, Ligia S. Palma, Luiz Fernando G. T. Amaral
AN INHERENTLY LINEAR TRANSDUCER USING THERMAL SIGMA-DELTA MODULATOR

The aim of this article is to describe a feedback circuit with thermoresistive sensor based on thermal sigma-delta modulator. The circuit uses 1-bit first order sigma-delta modulator in which a considerable part of conversion functions is performed by the sensor. This transducer circuit is able to measure digital physical quantities that interact with the sensor: temperature, thermal radiation and fluid velocity. In this study, it is used to measure environment temperature, on which digital output is linearly dependent. Equations that support circuit behaviour, simulation results and experimental results are shown. Two architectures are presented, one completely analogue and other with some parts digitally implemented using microcontroller. In addition, it is presented a thermal radiation architecture version in which digital output is intrinsically linear to the thermal radiation measure.

Janusz Zelezik, Stanislaw Walus
THE CONSTRUCTION OF THE MEASURING INSTRUMENTS AS THE SUBJECT OF MASTER'S THESES FROM METROLOGY OF NON-ELECTRICAL QUANTITIES

The students of automation and robotics, electronic and telecommunication are preparing their master's theses in Measurement Systems Group of Institute of Automatic Control. They also include the projecting and constructing of measuring instruments and measuring systems. These are dedicated to the laboratories in the Institute, as well for industry. The pocket radiometer was projected and constructed. It consists of the primary device with Geiger-Müller counter, the secondary device and of the power supply. The radiometer has series connections RS232C. The calibration stand for rotameters based on the soap film flowmeter principle was projected and constructed and put on the market. The digital measuring interface was projected and constructed for investigating of the piezoresistors (for strange gages, pressure gages, ...). The universal interface for transducers UTI and the microcomputer AT89C52 are used. The sensors can be used in the bridge or half-bridge, and for the resistance of 120 - 10000 ohms. The results of measurements are displayed on LCD display. The instrument is connected with help of the RS 232C interface with computer.

Madiar Zaripov, Irina Petrova, Victoria Zaripova
PROJECT OF CREATION OF KNOWLEDGE BASE ON PHYSICAL AND TECHNOLOGICAL EFFECTS

In the new millennium the change of technological and technique generations occurs in a temp unprecedented earlier. Therefore in order to train high-qualified engineers able to quickly, efficiently react to society’s new needs it is necessary for them to upgrade their knowledge permanently.
Indicators consumption increase both in quantity and in nomenclature needs an acceleration of production rate owing to automation of design process. The problem is that a description of various physical processes on which the principle of indicators action is based, is being carried out with the use of physic-mathematical apparatus, appropriate to this class of phenomena. It hampers the design process automation, increases new indicators development time and their cost. The article considers a united system approach in the field of sensitive elements theory, invariant to the physical nature of phenomena and processes used and in the field of methods and instrumental means of these elements structural designing with following process automation.

Page 730 of 936 Results 7291 - 7300 of 9356