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Page 727 of 977 Results 7261 - 7270 of 9762

Maurizio Bovi, Maria Pia Toni, Isabelle Aubineau-Lanièce, Jean-Marc Bordy, João Cardoso, Bruno Chauvenet, Frantisek Gabris, Jan-Erik Grindborg, Antonio Stefano Guerra, Antti Kosunen, Carlos Oliveira, Maria Pimpinella, Th
TRACEABILITY TO ABSORBED-DOSE-TO-WATER PRIMARY STANDARDS IN DOSIMETRY OF BRACHYTHERAPY SOURCES USED FOR RADIOTHERAPIC

In the current brachytherapy practice, the procedures to determine the absorbed dose imparted to the patient are affected by an uncertainty higher than in radiotherapy with external beams. That could reduce the success of brachytherapy treatments. Most of the uncertainty is due to a lacking metrology: no absorbed-dose primary standards are so far available to assure direct traceability in dosimetry of brachytherapy sources. This paper outlines the project "Increasing cancer treatment efficacy using 3D brachytherapy", co-funded in the framework of the project iMERA-Plus according to the Grant Agreement No. 217257 between the European Commission and the European Association of National Metrology Institutes. The aim of the project is to develop methods for the direct measurement of the absorbed dose to water and to extend the use of this reference quantity to brachytherapy dosimetry with an uncertainty on the dose delivered to the target volume less than 5% (k = 1) at clinical level. The present project will potentially increase the accuracy and safety of brachytherapy to a level comparable to that typical of radiotherapy with external accelerator beams.

Vadim Geurkov, Valeri Kirischian, Lev Kirischian
SIGNATURE TESTING OF ANALOG-TO-DIGITAL CONVERTERS

When testing an analog-to-digital converter (ADC) by automatic test equipment (ATE), the latter is capable of performing extensive processing of output responses of the ADC. This allows detection of virtually any fault. However, the cost of ATE is quite high. As well, the external bandwidth of ATE is normally lower than the internal bandwidth of the ADC being tested, which makes it difficult to accomplish at-speed testing. It is important, therefore, to embed test hardware into ADC itself. The methods employed at ATE are complex and inconvenient for built-in realization. More advantageous are the methods exploiting accumulation of output responses. The size of the accumulator depends on the number of responses. In order to achieve greater fault coverage, this number is kept large, complicating the implementation. On the other hand, signature analysis used in digital systems testing is well suited for compaction of "lengthy" responses, and it is characterized by small hardware overhead and low aliasing probability. In this work, we apply signature analysis principle for compaction of output responses of an ADC. The permissible tolerance bounds for a fault-free ADC are determined and the aliasing rate is estimated. Examples are given.

Jorge Trota Filho, Renato Reis Machado, Sérgio Pinheiro de Oliveira, Cláudio Afonso Koch, Islei Domingues da Silva
ESTIMATION OF UNCERTAINTY IN ROCKWELL HARDNESS DIAMOND CONE INDENTERS

This work aims to validate the creation of a relationship between the direct and indirect calibrations of Rockwell C hardness diamond cone indenters. The resulting modelling allows the prediction of the indenters behaviour based on direct calibration. The uncertainty of indenters was obtained from the graph of uncertainty related to the Primary Hardness Standard Machine as a function of the uncertainty related to the Primary System for Calibration of Indenters. For mounting the experimental set-up it was necessary to use a lot of indenters, and their characteristics helped to model the behaviour of any other indenters. The majority of the results showed a good agreement between the uncertainty obtained from the indirect calibration and the uncertainty from the graphs used to create the mentioned model.

Jay H. Hendricks, Douglas A. Olson
NIST EXPERIENCE WITH NON-ROTATING FORCE-BALANCED PISTON GUAGES FOR LOW PRESSURE METROLOGY

The National Institute of Standards and Technology (NIST) Low Pressure Manometry Project maintains and operates primary standard ultrasonic interferometer manometers (UIMs) over the pressure range of 1 mPa to 360 kPa. Over the past decade a new type of customer gauge, the non-rotating force-balanced piston gauge or FPG (model 8601, DH Instruments, a Fluke Company has been introduced to the standards community that covers the range of ˜1 Pa of 15 000 Pa and is capable of both absolute and differential measurement modes. Since 2002, NIST customers have requested that four different FPG units be compared to the NIST primary pressure manometer standards (UIMs). The results of the comparisons were that all four FPG units were within manufacturers stated uncertainty (0.008 Pa + 30 × 10-6 × P for absolute mode) when compared against the NIST UIMs at pressures between 10 Pa to 15 000 Pa (absolute mode). At pressures between 5 Pa to 10 Pa, the results were generally within manufacturer’s specifications. Below 5 Pa some of the FPG units were outside of manufacturer’s uncertainty specifications. The use of an isolating capacitance diaphragm gauge (CDG) was necessary during the comparisons to prevent humidified gas from the FPG from entering the NIST 160 kPa mercury UIM primary pressure standard. The results of these four different comparison tests will be discussed in detail, along with test conditions, equipment set-up, and test uncertainty analysis.

Jorge Trota Filho, Sérgio Pinheiro de Oliveira, Islei Domingues da Silva, Renato Reis Machado, Cláudio Afonso Koch
STUDY OF THE BEST MEASUREMENT CAPABILITY IN ROCKWELL SCALE AT THE BRAZILIAN NMI INMETRO'S PRIMARY HARDNESS STANDARD MACHINE

This paper shows the actual status of an on-going metrological research that aims an upgrade of the current Rockwell C hardness scale´s best measurement capability (BMC), e.g. 0.3 HRC, referred to the Primary Hardness Standard Machine installed at the Brazilian NMI INMETRO. This value complies with the ISO hardness standards and the GUM uncertainty guide as well as the main eight uncertainty sources and respective sensitivity coefficients for the direct calibration method, detailed in the EURAMET hardness guide. This work shows that an increasing knowledge of the actual calculated sensitivity coefficients yields a consequent reduction in the BMC. These experimental coefficients were estimated by the use of up to six uncertainty sources. In this case, the BMC changed to 0.17 HRC (two significant digits) or 0.2 HRC (one significant digit).

Inseok Yang, Yong-Gyoo Kim, Chang Ho Song, Kee Hoon Kang, Kee Sool Gam
LOW TEMPERATURE CALIBRATION FACILITIES AT KRISS

We review the low temperature calibration facilities at the Korea Research Institute of Standards and Science. For the calibration of capsule-type standard resistance thermometers, open and sealed cells of cryogenic fixed points and their realization system were manufactured and used. A sealed cell of the triple point of Argon for long-stem standard platinum resistance thermometers was also manufactured. For calibration by comparison, a controllable comparison cryostat and a nitrogen boiling point temperature block were made. We also review our traceability scheme and supporting international key comparisons for the dissemination of low temperature standards.

Augusto P. Cunha, Ronaldo N. Azeredo
LEGAL METROLOGY AND THE AUTOMOTIVE AIR POLLUTION CONTROL IN BRAZIL

This paper will present metrology's role on air pollution control in Brazil, the benefits for society and how Inmetro's Legal Metrology Directorate (Dimel, in its Portuguese acronym) is developing this work. Automotive vehicles are very significant air pollution source in Brazil. To change this situation, two years later the Federal Government established the Automotive Vehicles Air Pollution Control Program (Proconve, in its Portuguese acronym), providing to the car manufacturers a gradual schedule to the implementation of cleaner automotive technologies on new vehicles. Today the exhaust emissions reduction for these vehicles is up to 97%.
For in-use vehicles, Proconve demanded to all Brazilian states the implementation of an Inspection and Maintenance (I/M) Program. At least once a year these vehicles should be submitted to an I/M authority to check its general conditions and to measure its exhaust emissions.
The emissions measurement is performed with two different instruments: gas analyzers (for spark ignition engines) and opacimeters (for Diesel engines). Both instruments are under legal metrological control and are submitted to type evaluation and verification, performed by National Institute of Metrology, Standardization and Industrial Quality (Inmetro).

Monique K. K. Figueiredo, Rodrigo P. B. Costa-Felix, André V. Alvarenga, Luiz E. Maggi, Marcio F. Portilho, Marcio N. Souza, Gilberto A. Romeiro
STUDY, DEVELOPMENT, AND IMPLEMENTATION OF ANALYSIS TECHNIQUE OF BIPHASIC ATTENUATION SYSTEMS USING ULTRASOUND

These papers describe the first set of experiment conducted to validate a measurement system for physical-chemistry analysis of fluids using ultrasound as principle. Frequencies of 2.25, 3.00, and 3.50 MHz were used, with the emission-reception technique with a pair of transducers. Experimental results showed excellent agreement with the theory for attenuation of glycerol at 99.5% of concentration. The system is able to be used in other liquids, being biofuels particularly of interest for this project.

Yoshihiro Fujioka, Kouta Miyake, Jianxin Sun, Toshiro Ono
DEVELOPMENT OF ACCURATE WEIGHING SYSTEM USED UNDER THE VIBRATION - LIKE MOVING CONDITIONS VERIFICATION OF WEGHING SYSTEM WITH 3 ACCELEROMETERS

This research deals with a weighing system used under the conditions in which various movements exist. These various movements are heaving motion, rolling motion, pitching motion, etc. In this paper, these various movements are collectively called as "vibration-like movements". The term of "vibration-like moving conditions" means the conditions in which vibration-like movements exist. In a previous paper, the weighing system which has 3 dummy loadcells is discussed. "Dummy loadcell" is the loadcell which observes the vibration-like movements. We manufactured the weighing system and made several experiments with the weighing system. As a result of those experiments, it is confirmed that the proposed method is able to weigh under the vibration-like moving conditions accurately.
The purpose of this research is the practical realization of the weighing system. In order to put the weighing system into practical use, it is needed to reduce the size and weight of the weighing system. Accelerometers are substituted for the dummy loadcells. Generally, accelerometers are lighter and smaller than loadcells. This research verifies the effectiveness of the weighing system with "dummy accelerometers".

Cleonilson Protásio de Souza, Tiago Pontes Pereira, Raimundo C. S. Freire
ELECTROCARDIOGRAM BY MOBILE PHONE: A COMPRESSION METHOD FOR SMS

The increasing development on mobile communication allows the design of new applications in different areas. Telemedicine is one of these areas and studies and researches on it are of extremely importance to the society. An important application in telemedicine is the use of electrocardiogram (ECG) to transmit ECG test remotely in a compact or portable way. However, ECG transmission technology available today is still expensive and is based on use of modems and, recently, PDAs. On this context, a portable ECG device based on mobile phone is welcome. A basic mobile service is the Short Message Service (SMS) that is present at all mobile phone at extremely low cost. To take advantage of SMS on design of a mobile ECG, it is need efficient compression methods to compress the ECG signal into a message. In this work is present a compression method that allows mobile phone to transmit ECG signal via SMS.

Page 727 of 977 Results 7261 - 7270 of 9762