HITU (High Intensity Theraupetic Ultrasound) transducers are widely used in therapeutic ultrasound in medicine. The output ultrasonic power of HITU transducer can be measured in number of methods ...described in IEC 61161 standard 1. New IEC standards specifically for measurement of HITU equipment are under development. The ultrasound power radiated from a transducer is dependent on applied input electrical voltage and current and consequently power. But, up to now, no standardised method has been developed and adopted for the input electrical power measurements. Hence, a workpackage was carried out for the establishment of such method in the frequency range of 1 to 3 MHz as a part of EURAMET EMRP Era-net plus "External Beam Cancer Therapy" project. Several current shunts were developed and evaluated. Current measurements were also realized with Philips current probe and preamplifier at NPL and Agilent current probe at UME. In this paper, a method for the measurement of instantaneous electrical power delivered to a reactive ultrasound transducer in the required frequency range is explored.
A new design for calculable resistor Gulmez, Y.; Gulmez, G.; Turhan, E. ...
Conference Digest Conference on Precision Electromagnetic Measurements,
2002
Conference Proceeding
UME has improved a coaxial and bifilar type of resistors that have been widely used for determining of the resistance unit from DC to up to several kHz at many primary laboratories. This paper ...describes the modeling, construction and measurement results of the calculable resistors, which are specially designed in order to eliminate the effects of vibration and mechanical shocks during transportation, at a nominal value of 1 k/spl Omega/, 10 k/spl Omega/ and 12,906 k/spl Omega/.
A microwave humidity measurement system based on microwave resonance has been developed at TÜBİTAK UME (National Metrology Institute of Turkey). This technique is based on microwave resonance ...frequency detection of a cavity that is sensitive to permittivity of air and water content. We have designed a copper microwave cavity resonator, a microwave electronics and a software to measure relative permittivity of air. Experimental results show good agreement with traditional humidity measurements in the range from 25% RH to 80% RH.
The Impedance Group Laboratories of National Metrology Institute of Turkey previously developed a new method for the characterization of Agilent 16380A-type four-terminal-pair air dielectric ...capacitance standards ranged from 1 to 1,000 pF up to 30 MHz. This method is based on obtaining all resonance frequencies of standard capacitors using a vector network analyzer in order to calculate inductive residual parameters of the standards. As a continuation of the study, this paper gives a detailed uncertainty analysis for the method.
National Metrology Institute of Turkey (TÜBİTAK UME) has developed a new approach for the characterization of Agilent 16380A-type four-terminal-pair (4TP) air dielectric capacitance standards in ...the range of 1 pF to 1000 pF up to 30 MHz. This method is based on determining all residual inductive parameters of 4TP standard air dielectric capacitors from resonance frequencies. These resonance frequencies were calculated using impedance and admittance values obtained from scattering parameter measurements up to 500 MHz employing a vector network analyzer. Capacitive residual parameters were measured by using a 1 kHz capacitance bridge.
The efficiency of education in East and Southeast Turkey (E&SE) has long been a subject of debate. Both regions are similar to each other and different from the other regions in terms of economy, ...culture, ethnic origin, and languages spoken. Sahin (1997) studied the efficiency of education in the E&SE and proposed that illiteracy is significantly the highest in both regions, the female student population is significantly lower, and students are significantly less successful in nationwide general proficiency examinations (OSS and OYS) compared to all the other regions. Social sources of failure were studied in terms of the distinguishing characteristics of both regions, from both practical and theoretical standpoints. The findings indicated inequality of educational opportunity rooted in geographical, economical, social (cultural, linguistic), and political factors.
In this study, it is aimed to fabricate DC current shunt in the range from 1 A to 10 A with high accuracy and low drift. Resistance value of shunt was chosen as 10 mΩ which is compatible to the ...national traceability chain. 10 mΩ DC current shunt was fabricated, characterized and was put into use at TÜBİTAK UME (National Metrology Institute of Turkey) DC Resistance Laboratory.
The efficiency of education in achieving the national goals in East and Southeast Turkey (E&SE) has long been a subject of debate. Both regions are similar to each other and different from the other ...regions in terms of economy, culture, ethnic origin, and languages spoken. Separatist terrorist activities, economic decline, unemployment, and geographical dispersion are some aspects of the problems in both regions (Ergil, 1995; Özdag, 1995; RP, 1994; SHP, 1990). The lack of teachers, especially in rural schools, limited budgets, inequality in schooling and the failure of schools in E&SE Anatolia were identified as the educational problems by many authorities and published in the report of the 14th National Education Council in 1993 (NEC, 1993). In order to draw a conclusion concerning the efficiency of education in the E&SE, all sources of information was studied and all related information was gathered and analyzed. This study is about the efficiency of education in the E&SE and proposed that illiteracy is significantly the highest in both regions, female student population is significantly lower, and students are significantly less successful in nationwide general proficiency examinations (OSS and OYS) compared to all the other regions. The results indicate inequality of educational opportunity mainly originated from the negligence of ethnic, cultural and lingual existence of the people in both regions. The solution seems to lie in either the application or the type of democracy.
The need of calibrated inductive voltage dividers (IVD) with the smallest possible uncertainties was appeared for determination, maintenance and dissemination of the ohm and the farad in audio ...frequencies. In this paper an IVD calibration system that is based on bootstrapping method is described and the preliminary results and improvement efforts are mentioned. The relative uncertainty of the system from the preliminary results is 2.10/sup -8/ for the inphase component, 5.10/sup -8/ for the quadrate component at 1 kHz.
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