In the present study, turbulent flow visualization is carried out to understand the vortex formation mechanism behind a trapezoidal bluff body, for vortex flowmeter application. The dye used for flow visualization is shear-thickening and high extension viscosity fluid, which can sustain turbulent separated flows. With the quantitative assessment of the images, the vortex frequency is computed which is in close match with the results obtained from Piezo-electric sensor based measurement. The study enhances the understanding of the complex vortex formation mechanism in the design of vortex...
In this paper we present the traceability chain for the calibration of the frequency of laser standards that realize the definition of the metre at the National Institute of Metrological Research (INRIM) in Italy in accordance with the mise en pratique issued by the CIPM. We describe the way our femtosecond laser frequency combs are referenced to the SI second and the new research activity on the production and testing of iodine cells.
The article describes the bath with a large aperture blackbody, purposely designed and constructed for calibration of thermal imagers. For interpretation of experimental results and also for determination of inner blackbody temperature a numerical model was build. Based on available equipment a calibration procedure for thermal imagers was developed with special emphasis on evaluation of entire imager FOV.
This work presents an approach to perform interlaboratory comparison of Articulated Arm Coordinate Measuring Machines (AACMM) with Virtual Spheres Plate (VSP) gauge. This gauge has a determined number of pyramidal inserts having four conic holes each. These inserts were designed to fit virtual spheres with coordinates of the four points determined by measurement. The gauge has to be delivered to the laboratories under evaluation and the diameter and the center-to-center distances among the virtual spheres must be determined to apply normalized error analysis. The results proved suitable to...
Romania, as a member state of European Union, started to develop together with its National Institute of Metrology, efficient measures to detect drivers under influence with accurate results and to assure the traceability of mass concentration of alcohol in exhaled breath. The paper describes the complete system used for testing of ethylometers performance and the method applied to prepare and certify the standard solutions. The expanded uncertainty for the complete simulator system was calculated taking into consideration all input quantities which have noticeable contribution to the final...
The best way that a National Metrology Institute (NMI) has to demonstrate confidence in its measurement results and, consequently, in its measurement capabilities is the the participation in key comparisons. Usually, it is not so obvious to choose the key comparison reference value (KCRV). The main purpose of this paper is to present the considerations done about the measurement results contained in some final reports of some different key comparisons, chosen as case studies, aiming to establish the KCRV.
The paper considers standardization problems and methods that are concerned with metrological characteristics of measuring instruments in the context of the system approach. The main aims and principles of standardizing and estimating metrological characteristics are presented. General objectives and possible methods of standardization are discussed. Related concepts of pattern and norm are analyzed. Proposals on improving standardization methods for various groups of measuring instruments are elaborated.
This paper has the purpose to show how the instability of travelling standards can affect the results of an interlaboratory comparison program, and how to evaluate its influence in the determination of these results, in order to not compromise the assessing of a laboratory when En value is used for this purpose. In this work are presented and discussed five options of instability compensation of the travelling standard.
The main objective of this paper is to describe the dependence of the reliability of estimates of the regression model due to measurement accuracy. The main focus is on the experiments with reduced number of the tests, especially on the D-optimal plans, because these types of experiments are nowadays very important in the industrial praxis.
We consider the problem how a mobile robot equipped with a sensory subsystem with multiple operation modes should focus its attention to provide optimal support for finding the shortest path to a given target. The path planning problem is considered as a search task in a directed graph. The path planning is linked to the focus of attention problem by noting that any observations made of the environment ultimately reveal us information on the arc weights in the graph, i.e. the cost function. The formulation allows us to describe consistently various phenomena affecting optimal paths in the...