IMEKO Event Proceedings

Page 780 of 855 Results 7791 - 7800 of 8545

Li Tao, Dai Ming, Lin Jing, Zhang Yue, Zhang Zhimin
THE TORQUE STANDARD MACHINES IN CHINA

This paper describes the development of torque standard machines in China, its measurement range and its measurement uncertainty information etc. Also, the situation of torque standard machines which are in building process or will be built in the future is described in this document. In 1970's, the first standard machine for measuring torques was developed in Shanghai and it initiated the history of torque measurement in China. In the whole development process, there appeared four types of machines, which are:
a) the rolling bearing type,
b) the knife-edge type,
c) the air-bearing type and
d) the flexible supporting type. Nowadays, the torque standard machines in China are developing to the direction of large torque, super-large torque, small torque and mini torque ranges, and they are stepping into the international level rank.

Adrian Gherasimov, Eugen Ghita
THE TRACEABILITY SYSTEM OF FORCE MEASUREMENTS IN ROMANIA

The paper presents some technical aspects about the Romanian system built-up to ensure the traceability of force measurements to the SI units. The regulations of the traceability schemes and the steps to be followed are presented. The Force Laboratory Timisoara, pending of Romanian Bureau of Legal Metrology proposed and implemented the national traceability of force measurements. The paper presents the best measurements capabilities, which the Romanian calibration laboratories offer for force measurements. In order to perform a national and international validation of the force measurements in Romania, the traceability system must be in accordance with the national and international standards. One of the major parameters of the traceability system is the uncertainty associated with calibration or measurement results. This trend is based on the explosive implementation of the ISO 9000 series and ISO 17025 requirements in industry and other fields. The Romanian Government putted forward some regulations in order to provide for the necessary conditions to report the results to the acknowledged standards.

S. Adamczak, D. Janecki
THE TRANSFORMATION OF THE ROUNDNESS PROFILE

Reference (especially two- and three-point) methods could not be applied to the accurate measurement of roundness profiles because of various drawbacks. Theoretical and experimental studies have proved that the only way to eliminate these drawbacks is to mathematically transform the profile measured by a reference method into the real profile. The transformation, whose fundamentals are presented and discussed in this work, enabled the development of an original computer program. The mathematical model of the transformation was statistically tested by means of a specially developed computer measuring system, and the results provided basis for the construction of measuring systems applicable to accurate measurements of roundness profiles directly in production.

Alice Lucchini, Mauro Bernabei
The tree species of Po valley Logboats

Logboats are present on many continents. Despite being made of a tree-trunk, they cannot be simplified to only one building tradition. In Italy, the main studies usually list the findings, but we lack knowledge about the timber and the vessel construction. In our study, 16 logboats, for a total of 69 samples, were analyzed to identify the tree species used in the different parts of the boats. Different tree species were identified, including oak (Quercus sp.), chestnut (Castanea sativa), and elm (Ulmus sp.). We found dogwood (Cornus mas) and willow (Salix sp.) in treenails, and in some cases, we detected the use of pieces of bark and phloem. Long believed to have been dug out from a single tree, our results demonstrate that these logboats also contain components made from woods different from the main hull. Thus, the traditionally accepted nomenclature seems inappropriate and likely to confuse research efforts.

Jan Fischer, Tomáš Radil, Jan Šedivý
THE TRIANGULATION METHOD OF CONTACT-LESS DIMENSION MEASUREMENT USING AN AREA CMOS IMAGING SENSOR

The so-called triangulation method of contact-less dimension measurement determines the measured object’s dimension from its shadow projected on an imaging sensor without lens. A point light source is used to illuminate the measured object. The so far used linear CCD sensors introduced a considerable uncertainty to the measurement. Application of area CMOS imaging sensors improves the measurement uncertainty and enables to use some new measurement methods. A special CMOS measuring camera was designed for this purpose.

K.D. Hill, A.G. Steele
THE TRIPLE POINT OF XENON: A CANDIDATE FIXED-POINT REFERENCE TEMPERATURE

The triple point of xenon has recently been shown to be a suitable fixed point for incorporation into the next revision of the International Temperature Scale as a means to reduce the non-uniqueness in the important 84 K to 273 K range. We summarize the results, which illustrate that the xenon triple point itself is highly reproducible, with a standard deviation of 48 µK for the eight melts of this study, and a total realization uncertainty of just 76 µK.

A. Schäfer
THE ULTRA-PRECISION INSTRUMENT DMP 41 – FIRST EXPERIENCES & APROPRIATE FILTER SETTINGS

Traceability of force/torque laboratories around the world widely relies on the strain gauge principle. In order to reach a high overall accuracy of the measuring chain reference transducers always have to be completed by an ultra-precision instrument for strain gauges. Therefore a very special architecture of A/D conversion & signal processing is used. GUI and interface realization determines the good interconnectivity of the device.

V. Skwarek, V. Hans
THE ULTRASONIC CROSS-CORRELATION FLOW METER – NEW INSIGHTS INTO THE PHYSICAL BACKGROUND

During the last years of research, flow measurement by the cross correlation method made much progress concerning accuracy and reliability. Especially for gaseous fluid the signal processing was far improved by new demodulation techniques such as undersampling and complex demodulation. This allows new insights into the physical principle of interaction between ultrasound and fluid introduced in this paper.

G. C. Stanbury, F. A. Davis
THE UNCERTAINTY EVALUATION OF NPL’S HARDNESS FACILITY

To understand the uncertainties in the calibration of hardness test blocks by NPL, it was necessary to evaluate the main factors contributing to the uncertainty in measurements made with the NPL hardness calibration machines. These factors were identified and then, where possible, directly verified. Factors that could not be directly verified were assessed using the best available information.
The verifications covered the force required to produce hardness indents, the measurement of the size of these indents, and the characterisation of the indenters.
As a result of the initial verification, modifications were made to the depth sensor on the Rockwell hardness tester.

Adrian Gherasimov, Eugen Ghita
THE UNCERTAINTY OF MEASUREMENT IN CALIBRATION USING A COMPARISON FORCE STANDARD MACHINE

The paper presents a practical example for the evaluation of the uncertainty in calibration using a comparison force standard machine with a maximum load of 1000 kN, tension and compression mode. The uncertainty of measurement associated with the input estimates is evaluated. It is also presented a way to minimize the uncertainty of the applied force with the view to attaining the necessary value for the calibration of class 1 force transducers, in accordance with ISO 376:1999. For this purpose an evaluation of the loading regime of the force machine is presented. There was identified the main input components influencing the uncertainty in calibrations, such as the force stability during measurements and the metrological characteristics of the reference transducers. Further are presented the practical results of the investigation of the force comparison machine after the optimization, including the technical and economical benefits.

Page 780 of 855 Results 7791 - 7800 of 8545