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Dimensional Metrology
Published in Richard Leach, Stuart T. Smith, Basics of Precision Engineering, 2017
Massimiliano Ferrucci, Han Haitjema, Richard Leach
Roundness and cylindricity are conditions for surfaces of revolution (ASME Y14.5 2009). The fundamental geometries for roundness and cylindricity are the circle and the cylinder, respectively. A circle is defined by the set of points that are equidistant to a common centre, whereas a cylinder is defined by the set of points that are equidistant to a common axis. It follows that roundness is the degree to which measured surface points deviate from equidistance to a common centre point, while cylindricity is the degree to which measured surface points deviate from equidistance to a common axis. Both measurements are defined for bodies of revolution, hence the results are presented as a function of rotation angle (Figure 5.18). Roundness measurements can be applied to objects with circular cross-sections, for example spheres, cones and cylinders, whereas cylindricity measurements are strictly for cylindrical objects. It is important to note that roundness and cylindricity are not measures of the object’s size, but instead are measures of variations in the object’s surface from the ideal form.
Factors Affecting the Performance of Talyrond Measurement Accuracy
Published in Salah H. R. Ali, Automotive Engine Metrology, 2017
The roundness feature means the change in the radius of an object and is usually referred to as “circularity” or “out- of-roundness.” The measure of roundness is expressed as the difference between the smallest and largest diameters, which can be expressed by peak and valley in metrology. To assist this measurement, a mathematical reference circle is used through machine software. The position of the reference circle to the measured profile and its center is not arbitrary and should be selected by the metrology engineer to ensure the measurement result that meets the required specifications [7]. The software package of the Talyrond machine includes specific important strategic techniques of measurement to be used in roundness assessment.
Sedimentary Texture
Published in Supriya Sengupta, Introduction to Sedimentology, 2017
Following Wadell, roundness is defined as the ratio of the average radius of curvature of the edges and corners of a grain to the curvature of the maximum inscribed sphere. Measurements on spheres being difficult, two-dimensional projections of grains are generally used. Roundness in such a case is expressed as: Roundness=(∑1Nri/N)/R,
Shape quantification of volcanic cinders and the influence of particle shape indexes on accumulation characteristics
Published in International Journal of Pavement Engineering, 2021
Zhihong Nie, Qun Qi, Xiang Wang, Zhengyu Liang, Aijun An
An algorithm that can accurately calculate roundness is developed based on the corner region recognition and inscribed circle fitting. Based on the average deviation distance between real contour and Fourier smooth contour, a roughness algorithm is proposed to describe the fluctuation of particle contour.The shape indexes of the volcanic cinder are normally distributed, in which the elongation has the widest variation range. The compactness is positively correlated with EI, and the effect of Rd on compactness greatly diminishes when Rd<0.4, while the accumulation behaviour is nearly unaffected by roughness.Elongation has a stronger effect on accumulation characteristics than roundness and roughness. The anisotropy degree of the contact force and contact fabric decreases with increasing EI. After EI exceeds 0.8, the force-fabric anisotropy is not affected by elongation.As a promising and low-cost fill material, volcanic cinder can be better used in subgrade construction by controlling elongation. EI not less than 0.7 is more suitable, which ensures that most volcanic cinder particles can be utilised, improving accumulation compactness, and reducing particle breakage.
Monitoring a municipal wastewater treatment process using a trend analysis
Published in Environmental Technology, 2018
Jani Tomperi, Esko Juuso, Anna Kuokkanen, Kauko Leiviskä
The wastewater samples for the on-line imaging were taken from the aeration tank of one activated sludge line. Here, two variables of the on-line optical monitoring, fractal dimension and roundness are presented. Roundness is defined as the ratio between the area of an object and the area of a circle with a diameter equal to the object’s length. The floc structure is described using the fractal dimension which is a measure of the irregularity of the perimeter.