Metrological Problems Research Articles (Page 5)

The comparative data obtained in the study show an averaged difference at the level of 1%. An innovative noninvasive measuring technology originally developed by a Russian R & D team offers measuring stroke volume of blood SV with a high accuracy. Conclusion In practice, it is necessary to take into account some possible errors in measurements caused by hardware. Special attention should be paid to systematic errors.

An Introduction to Quantum OptomechanicsWe provide an introduction to the description of mechanical systems in the quantum regime, and provide a review of the various types of micro-scale and nano-scale optomechanical and electromechanical systems. The aim is to achieve quantum control of micromechanical and nanomechanical resonators using the electromagnetic field. Such control requires the demonstration of state preparation (in particular, cooling to the ground state), coherent control and quantum-limited measurement. These problems are discussed in turn. Some particular problems in force detection, metrology, nonlinear optomechanics and many-body optomechanics are also discussed.

An improved method of interpreting the exact fraction method for the order of interference used in multiwavelength interferometry is examined. Optimal algorithms for choosing possible values of the integral orders of interference and a new, more exact method of calculating the result of two wavelength interference measurements are presented. The metrological problems of multiwavelength interferometry are shown to be closely related to the formalism of convergents of continued fractions in number theory.

Problems in fundamental metrology associated with variations in constants and the planned transition to new definitions of SI units based on fixed values of the fundamental physical constants are examined. It is pointed out that all the necessary conditions for such a transition have not yet been satisfied.

From macro scale to nano scale measurements, the relationship between measuring range and measuring accuracy is a key parameter for measuring abilities. When measuring targets are three-dimensional (3D) and include complex geometrical features, high-accuracy cannot be achieved by conventional measuring methods. In this article, we discuss the limitations of 3D metrology in micro and nano scale profile measurements. For nano and micro scale measurements, we have to develop three key technologies as intelligent measuring methods, in-process measurements and high-accuracy standards.

Hippocampal atrophy rates in Alzheimer's disease: Automated segmentation variability analysis

Blind separation of manufacturing variability with independent component analysis: A convolutive approach

A brief review of recent achievements in nanophotonics and the future prospects for its application in the receiving-transmitting channels of phased antenna arrays is given. It is shown that it is necessary to use nanophotonics to solve urgent problems of measurement techniques and metrology, including measurements of the space-time parameters of electromagnetic pulses. Some results of research on analog nanophotonics in systems for measuring the parameters of the receiving-transmitting channels of phased antenna arrays, carried out at the All-Russia Research Institute of Optophysical Measurements, and also an analysis of the problems of metrological support for measurements in this area are presented.

Flow rate measurement is a common task in many hydraulic infrastructures included in systems with a large impact on the economy. The quality requirements that such measurement must fulfil imply the best knowledge of the measurement results (estimates and measurement uncertainties). Methods such as those given by the Guide for the Expression of Uncertainty in Measurement (GUM) have been widely used as tools to evaluate measurement uncertainties. However, such methods have implicit assumptions on the nature of the mathematical models and the applicability conditions, which are not often taken into account by their users, who apply them regardless of the specific nature of the actual metrological problems. One such assumption is that the output probability function is Gaussian, which is true only if some input conditions are met. In practice, many metrological problems are described by mathematical models with non-ideal conditions, the measurement uncertainty solutions thus being quite different from those predicted by the GUM method. The development of metrological studies has shown that the Monte Carlo method is suitable to deal with non-ideal problems and has several advantages. One such advantage is particularly useful for the specific problem of flow rate measurement using a primary weighing method: the ability to give information on the output quantity probability function. In this way, it is possible not only to obtain the output quantity estimate but also to test the normality of the output measurement uncertainty interval, which in fact has a non-Gaussian shape.

The precision of measurements performed by atomic-force microscopy (AFM) and high-resolution electron microscopy (HREM) for solving problems of metrology and diagnostics of solid nanostructures is discussed. The HREM-measured height of a monatomic step on a Si(111) surface covered by a thin natural oxide film is demonstrated to be 0.314 ± 0.001 nm. The same accuracy is ensured by AFM measurements through controlling the Si surface relief with heating in ultra-high vacuum on specially created test objects with the distance between the steps being approximately 2 µm. It is shown that the geometric phase method can be used to quantify the strains in the crystal lattice of strained heterostructures on the basis of HREM images with accuracy to 10−4%, and in situ irradiation by electrons in HREM measurements can be used to visualize ordered clusterization of vacancies and self-interstitial atoms in {113} planes in Si samples.

Some trends in research on the physics underlying metrology as the science of measurement are examined. The basic problems and the prospects for their solution are analyzed.

Rigorous 3-D finite-difference time-domain computer simulations are used to investigate the electromagnetic characteristics of the diffraction output of a millimeter (mm)-wave-band relativistic magnetron. In the simulations, the diffraction output is outfitted with a dielectric grating that can be tuned in either reflection or transmission mode at definite operation wavelengths. This grating acts as a tunable filter of high-power oscillations generated by the magnetron and is similar to gratings widely used in optics to control ultrashort power optical pulses. Specifically, computer simulations establish a relation between the generation wavelength of the magnetron and the configuration of the grating, as well as predict that the grating provides the field reduction of up to -40 dB. The application of the grating suggests an approach to spectral measurements of mm-wave-band relativistic magnetrons with a measurement accuracy of better than 0.3 mm. The implementation of the approach solves a series of engineering and metrological problems arising during spectral measurements of a variety of high-power vacuum microwave devices.

Abstract Millisecond and binary pulsars are the most stable astronomical standards of frequency. They can be applied to solving a number of problems in astronomy and time-keeping metrology including the search for a stochastic gravitational wave background in the early universe, testing general relativity, and establishing a new time-scale. The full exploration of pulsar properties requires that proper unbiased estimates of spin and orbital parameters of the pulsar be obtained. These estimates depend essentially on the random noise components present in pulsar timing residuals. The instrumental white noise has predictable statistical properties and makes no harm for interpretation of timing observations, while the astrophysical/geophyeical low-frequency noise corrupts them, thus, reducing the quality of tests of general relativity and decreasing the stability of the pulsar time scale.

Efficient representation and computation of geometric uncertainty: The linear parametric model

State of art in standardization in GPS area

Methods for certifying verification facilities and the metrological characteristics of analytical instruments are considered.

In concert halls and other performance spaces it is important that acoustic conditions allow the musicians to hear each other and that there is a sufficient response from the room. Acoustical characterization of spaces for musicians, such as orchestra platforms, orchestra pits, and rehearsal rooms requires the measurements of the Early and Late Support, and other acoustical parameters described in the ISO/DC 3382-1 and in Literature. This work shows results from measurements carried out on five orchestra platforms, different in shape, size and materials of the boundary surfaces. Up to eight source positions were chosen in order to represent the main instrumental sections of the orchestra playing on the platform. Measurements were carried out without musicians, in conditions of empty stage and stage equipped as in concert configuration with stands, chairs, and risers. Some metrological problems connected with the reproducibility of results are considered as the directivity of the source and the small movements of the source and the microphone. The correlations between objective data show that the measured parameters are not always independent, but some groups of correlated measures, not completely separated, are found. The comparison of results allows to draw some connections with the main stage architectural features.

Abstract Mathematical modelling plays an increasingly important role in measurement science where many problems of fundamental and practical importance require solutions at meso‐ and nano‐scales. In quantum and materials metrology atomistic simulation has developed to a level where it is competing in accuracy with laboratory measurements. This article gives a brief overview of current applications of atomistic simulation to problems of metrology. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Secondary mass standards are usually made of stainless steel. One of the main problems in mass metrology is the stability of such stainless steel standards. Consequently, new materials have been investigated for the realization of mass standards, and this has led to the selection of nickel-based superalloys. The stability of materials is strongly dependent on surface reactivity; accelerated oxidation tests were performed, either in dry or wet air, and after a kinetic study, microstructural analysis of the oxide films was performed by scanning electron microscopy. The structure of the oxide films was also characterized by grazing x-ray diffraction and finally by x-ray photoelectron spectrometry (XPS) analysis. XPS associated with sputtering by argon ions allowed us to differentiate the nature of the oxides from the outer surface to a given depth in the film.

A description is given of a digital method of measuring the energy spectrum of a stationary random process in terms of the covariance function. A comprehensive approach is described to the determination of the error in this method. It is shown that there are advantages over the existing approach.