Metrological Problems Research Articles

Problems of optical monitoring of melt level and diameter of a crystal growing from high-temperature melt by Czochralski technique are considered. Investigations results performed in Institute of Automatics and Electrometry of the Siberian Branch of the Russian Academy of Science at vision system construction to control the automatic growth installations are presented. Such system consists of laser triangulation sensor used to measure the melt level in a crucible and also of digital vision system to control the diameter of growing crystal. Metrological problems important to control of crystal growth process caused by nonstationarity and variations of melt surface curvature and also by parallax of crystallization zone image formed by optical projection system are analyzed. Joint measurements of melt level andcrystal diameter are discussed allowing to eliminate a systematic measurement error caused by melt rotation.

It is shown that the parameters of foundry objects are usually hardly measurable, which creates serious metrological problems in the organization of the ACS for such processes. The system of selection of the metrological support, including obtaining the time-space mapping from the object and its convolution to the measurement result based on the classification of the measurement methods using Kohonen neural networks with an open set of classes is proposed. On the example of sand casting process, the operation of the system of selection of measurement methods for various manufacturing process stages with six-tuple of discrete characteristics of the measurement object at the system input and one of the known methods at the output is shown. The system provides for the expansion of the known list of measurement methods, thereby determining the direction of the scientific search for researchers-metrologists.

Metrology for New Generation Nuclear Power Plants–MetroFission

During the last decades, Digital Signal Processing techniques and devices have undergone an impressive evolution that led their performance to increase manifold. One of the fields that has greatly benefited of this evolution is that of instrumentation and measurement. DSP-based techniques are presently the most employed techniques in industrial and scientific measurement applications, so that modern instruments are actually computers with dedicated interfaces and dedicated software. The full exploitation of the computing features has led to the development of the Virtual Instruments, and, more recently, to the development of Distributed Instruments. This paper is aimed at briefly discussing the architecture of the modern Virtual, Distributed Instruments, some of their most significant applications and the major metrological problems raised by these systems.

Erratum to: Aggregation of Preferences as a Method of Solving Problems in Metrology and Measurement Technique

<p>This is a reissue of a paper which appeared in ACTA IMEKO 1979, Proceedings of the 8th IMEKO Congress of the International Measurement Confederation, "Measurement for progress in science and technology", 21.-27.5.1979, Moscow, vol. 3, pp. 607-626.</p><p>Common interest of both metrologists and representatives of science and technology in constant improvement of measurements as well as general trends in the development of research in the field of metrology, measurement technology and instrumentation at the present-day stage are shown. Problems of general metrology, of improving systems of units and standards ("natural" standards in particular) are considered in detail.</p>

We show the possibility of usefully applying procedures for preference aggregation in processing interlaboratory comparison results and organizing the transmission of measurement data over wireless sensor networks.

Characterization of 235U Targets for the Development of a Secondary Neutron Fluence Standard

We have formulated the uncertainty principle from the viewpoint of metrological and statistical problems. A comparison between the error and uncertainty paradigms has been made. The possibility of applying the uncertainty principle to the processing of experimental measurement data has been analyzed.

Computational metrology is referred to as a measurement method where a complicated measurement process is modeled as a forward problem and some measured data are obtained by a specific instrument under a certain measurement configuration, and then the measurands are precisely and accurately reconstructed by solving the corresponding inverse problem. The fundamental concept and characteristics of computational metrology are put forward, and it is pointed out that computational metrology is essentially a model-based metrology and a typical process to solve an inverse problem. The common scientific problems in computational metrology, such as the measurability, the measurement error analysis and precision estimation, the measurement configuration optimization, the fast and accurate forward modeling, and the fast and robust measurand reconstruction, and their generalized solution methods are explored, with an emphasis on the significance and necessity to apply modern mathematical theories and tools in solving the related problems. Some case studies are presented and have demonstrated that computational metrology is expected to provide a novel means for fast, low-cost, non-destructive, and accurate measurement in high-volume manufacturing.

Metrological problems related to normative and mathematical support of technosphere objects’ safety vector dynamic parameters
 spatial control are considered in this paper. On the example of analysis of regulatory documents regulating dynamic surveys,
 the absence evidence in these documents of necessary and sufficient criteria for practical realization of safety problems have
 been presented. On the basis of results related to dynamic surveys of technosphere’s real objects it has been shown that existing
 regulatory approach doesn´t allow to identify controlled forms of vibrations of buildings and constructions.

The MetroFission project, a Joint Research Project within the European Metrology Research Program, aims at addressing a number of metrological problems involved in the design of proposed Generation IV nuclear reactors. As part of this project a secondary neutron fluence standard is being developed and tested at the neutron time-of-flight facility GELINA of the JRCs Institute for Reference Materials and Measurements. Such a secondary standard will help to arrive at the neutron cross section measurement uncertainties required for the design and safety assessment of new generation power plants and fuel cycles. Such a neutron fluence device contains targets for which the neutron induced cross section is considered to be a standard. A careful preparation and characterization of these samples is an essential part of the development of the secondary standard. In this framework a set of 235U targets has been produced by vapour deposition of UF4 on aluminium backings by IRMMs target preparation laboratory. These targets have been characterized for both their total mass and mass distribution over the sample area.

Regulatory measurements of particle mass concentration in air, such as PM10 and PM2.5, have been required in Europe for many years, but have been problematic as issues affecting the comparability of measurements, even when made by the reference method, have become apparent. The importance of airborne particulate matter for human health, and the complexity of the atmospheric processes affecting it, have led to many other parameters, such as particle number concentration, size distribution and composition being monitored, in some cases also as a regulatory requirement. Generally the metrological aspects have been covered by the monitoring network operators, with little involvement from National Metrology Institutes (NMIs). The United Kingdom (UK) National Physical Laboratory is unusual in being an NMI that also operates air quality networks on behalf of the government, directly involved in the full range of activities from fundamental metrology, standardisation of methods, and field operation. More recently, some of the measurement issues have started to be addressed by a group of NMIs within the European Metrology Research Programme. This paper outlines some of the key metrological problems in this area, and the current position in dealing with them from a UK and European perspective.

Current problems of noncontact temperature measurements, connected with the lack of control over the systematic error in practice, are considered. It is shown that it is necessary to establish national recommendations to regulate the development of procedures. A promising direction for the development of pyrometry, involving the use of intelligent measuring instruments, is proposed.

Ordinal measurement, preference aggregation and interlaboratory comparisons

The concepts and definitions of smart sensors are analyzed and their minimal structure and functions are made more precise. A review is provided of existing standards aimed at unification of digital sensor interfaces, simplification of sensor network creation, insertion of smart sensors into networks, and network access to sensor resources.

Metas.UncLib is a software library that facilitates the linear propagation of uncertainties through a measurement model. It is able to handle complex-valued and multivariate quantities and supports higher mathematics. It is therefore able to deal with advanced metrological problems that require, e.g., matrix manipulations. The software is optimized for short computation times and low memory use.

The quality of working surfaces develops in the course of any method of processing parts, especially in processing that is accompanied by the removal of material by a cutting tool, hence it is impossible to obtain an ideal surface [1]. The degree of finish of a surface is estimated by means of a set of indicators, including roughness, residual stress, surface hardness, and others. This means that under particular application conditions, not only is it necessary to select the properties of a surface, but definite requirements must also be established for these properties. Therefore, one of the more important metrological problems in the analysis of the roughness of a surface with the use of thickness gage profilometers is to extract from the measurement results individual frequency components that characterize, strictly speaking, the roughness of a surface, its degree of undulation, deviation from form, and the noise that inevitably accompanies a measurement process. The use of the apparatus of Fourier transformations and of the corresponding frequency filters for this purpose have led to the development of standards that regulate the characteristics of these filters. The use of standard filters often limits the practical application of investigations directed towards the search for relationships between different characteristics of the technological process or equipment and individual components of the roughness of the resulting surfaces. The standard filters that are used in modern measurement systems and that assure that required cut-offs in steps λs, λc, and λƒ are obtained have flat frequency-amplitude characteristics, which makes it impossible to achieve a clear identification of the individual components of the initial profile [2]. Through the use of the Hilbert‐Huang transformation it becomes possible to extract from the results of measurements individual components related to those enumerated earlier in a natural way corresponding to the processing of the profilometer pattern [3]. We will consider the capabilities achieved with the use of the Hilbert‐Huang transformation, using as an example an analysis of the profile [4] presented in Fig. 1. Following removal of redundant fragments, the profilometer profile is imported into the Mathcad software package, where further processing of the profile is carried out. The maxima and minima of the profile are calculated in accordance with the following algorithm:

A method to characterize permanent and fast-pulsed iron-dominated magnets with small apertures is presented. The harmonic coil measurement technique is enhanced specifically for small-aperture magnets by (1) in situ calibration, for facing search-coil production inaccuracy, (2) rotating the magnet around its axis, for correcting systematic effects, and (3) measuring magnetic fluxes by stationary coils at different angular positions for measuring fast pulsed magnets. This method allows a quadrupole magnet for particle accelerators to be characterized completely, by assessing multipole field components, magnetic axis position, and field direction. In this paper, initially the metrological problems arising from testing small-aperture magnets are highlighted. Then, the basic ideas of the proposed method and the architecture of the corresponding measurement system are illustrated. Finally, experimental validation results are shown for small-aperture permanent and fast-ramped quadrupole magnets for the new linear accelerator Linac4 at CERN (European Organization for Nuclear Research).

The conditions for the formation of a holographic prism of modification II (for which a beam of diffracted rays is induced by a reference laser beam in the plane oriented perpendicularly to the reference beam) are described. A sample of this prism is implemented experimentally, and its response to the signal (reference) beam is demonstrated. Two modifications of a holographic prism as a basis for solving metrological problems of storing and reproducing flat angles and transferring the angle size to gradable and/or calibrated angle-measuring tools are compared. Each modification is found to have advantages in particular fields; thus, none can be considered as unconditionally preferred. The final choice of a particular modification can be made only after detailed analysis of the devices on their basis.