Multifractal analysis of ultrasonically machined surfaces of cylindrical quartz crystals: the effect of the abrasive grits

Since synthetic quartz is essential to produce 3-D resonators for numerous applications in precision electronics, in this work the surface topography of cylindrical quartz bars is investigated using the multifractal technique. The cylindrical bars were manufactured with ultrasonic machining using with five SiC grits ranging from 6 to 50 µm. The machined surfaces were initially characterized by contact profilometry and scanning electron microscopy (SEM). The multifractality of the machined surfaces was scrutinized using a box-counting method applied to the images obtained with 500X magnification. The multifractal spectrum indicated that the fractal dimension f(α) and the width of the fractal spectrum Δα are dependent on the grit size, but this dependence is not monotonic. The lowest (negative) value for Δf(α) was found for 25 µm grits indicating that for these grits the lower frequency events (grooves with tens µm width occurring along the USM direction) controls the surface topography much more than high frequency events related to brittle microcracking. The abrasive wear due to the continuous slurry recycling in lateral tool-workpiece interfaces contributed to smooth the groove texture as well as the sharpness of microscopic indentations, which remained observed on the surfaces machined with 50 µm grits. The opposite paths observed for the arithmetical mean deviation of the measured profile (Ra) and Δf(α) parameters with the cutting rate measured for each grit size were valuable to differentiate flat-rough and unlevelled-rough topographies in quartz bars.

The K–T boundary strata north of Korsnæb, Stevns Klint, Denmark – evolution and geometry revealed in a long, horizontal profile

A 460 m long profile of the Cretaceous–Paleogene (K–T) boundary strata at Stevns Klint was measured by the late Professor A. Rosenkrantz probably in 1944. The measured profile was inherited by Finn Surlyk around 1974 together with other original boundary data. This material was dug up in a long-forgotten drawer in connection with detailed field work by the co-authors on the boundary succession in the late spring and summer of 2021. The profile illustrates the stratigraphy, geometry and palaeotopography of the boundary strata in unprecedented detail. The part of the cliff illustrated in the profile is today partly covered by beach ridges composed of flint rubble but is situated below the finest section of the lower Danian bryozoan mounds exposed at Stevns Klint. This coastal section is situated immediately adjacent to a large limestone quarry and was planned to be quarried away around 1937, but was saved by A. Rosenkrantz who demonstrated its great scientific and educational value to the authorities.

Application of laser profilograph in the assessment of mechanical tillage of slope lands

The article analyzes an extensive set of measurements of the daily surface profile of cultivated soil in order to justify the moving average method for evaluating morphological parameters and studying the influence of the base length of the profile on the accuracy of the obtained values. The surface roughness for the elementary platform was 5.08 mm, the surface ridge formed by technological furrows was 21.9 mm, and the slope of the platform was 0.056 or 3.2 degrees. The accuracy of the obtained values of roughness and ridges of the surface of the treated soil depends significantly on the length of the profile under study, determined by the number of measurements performed. For one turn of the device for the elementary platform, 9616 data points were obtained on the profile length of 6.3 m (3 measurements are performed per 2 mm). The surface roughness varied from 2 mm to 6 mm, and the ridge – 16 ... 28 mm with the number of measurements from 2000 to 9600. When the measured profile length is about 1.3 m or less (no more than 2000 points), the parameters of the treated soil cover are greatly underestimated, and this error is greater for ploughed soil than for cored soil. On flatter surfaces, the base profile length of 2.5 m may be sufficient to adequately calculate the parameters of the daily soil surface.

Mapping the local dielectric constant of a biological nanostructured system

The aim of this work is to determine the varying dielectric constant of a biological nanostructured system via electrostatic force microscopy (EFM) and to show how this method is useful to study natural photonic crystals. We mapped the dielectric constant of the cross section of the posterior wing of the damselfly Chalcopteryx rutilans with nanometric resolution. We obtained structural information on its constitutive nanolayers and the absolute values of their dielectric constant. By relating the measured profile of the static dielectric constant to the profile of the refractive index in the visible range, combined with optical reflectance measurements and simulation, we were able to describe the origin of the strongly iridescent wing colors of this Amazonian rainforest damselfly. The method we demonstrate here should be useful for the study of other biological nanostructured systems.

Mapping the local dielectric constant of a bio‑nanostructured system

The aim of this work is to determine the dielectric constant value of a bio-nanostructured system via Electrostatic Force Microscopy (EFM) and to show how this method is useful to study natural photonic crystals. We mapped the dielectric constant of the cross-section of the posterior wing of the damselfly Chalcopteryx rutilans with nanometric resolution and obtained not only structural information on its constitutive nanolayers but also on the absolute values of the dielectric constant variation in a nanometric scale. By relating the measured profile of the static dielectric constant to the profile of the refractive index in the visible range, combined with optical reflectance measurements and simulation, we were able to describe the origin of the strongly iridescent wing colors of this Amazonian rainforest damselfly. The method we demonstrate here should be useful for the study of other nanostructured biological systems.

Application of profilograph for evaluation of mechanical tillage of slope lands

In this paper, we analyze a wide range of measurements of the day surface profile of tilled soil in order to substantiate the moving average method for evaluating morphological parameters and studying the influence of the base profile length on the accuracy of the obtained values. The surface roughness of the elementary plot was 4 mm, the surface ridgeness formed by technological furrows was 16 mm, and the slope of the plot was 0.198. The accuracy of the obtained values of roughness and ridgeness of the tilled soil surface depends significantly on the profile length determined by the number of measurements performed. We obtained 5273 data points per one turn of the device on a 6.3 m profile length (1 measurements are made per 1 mm) for the elementary plot. The surface roughness varied from 3, 1 mm to 4, 3 mm, and the ridgeness – 12 ... 21 mm when the number of measurements is from 2000 to 5273. When the measured profile length is about 1.3 m or less (not more 2000 points), the parameters of the tilled soil cover are not considered important. However, they are more critical for ploughed soil than for harrowed soil. On flatter surfaces, the base profile length of 2.5 m may be sufficient to adequately calculate the parameters of the day soil surface.

Robot-Assisted Floor Surface Profiling Using Low-Cost Sensors

Low cost and accurate 3D surface profiling can help in numerous industry applications including inspection tasks, cleaning, minimizing bumps in navigation of non-uniform terrain, aid navigation, and road/pavement condition analysis. However, most of the available systems are costly or inaccessible for widespread use. This research presents investigation into the capability of cheap and accessible sensors to capture the floor surface profile information. A differential drive robotic platform has been developed to perform testing and conduct the research. 2D localization methods are extrapolated into 3D for the floor capturing process. Two different types of sensors, a 2D laser scanner and an RGB-D camera, are used for comparison of the floor profile capture ability. The robotic system is able to successfully capture the floor surface profile of a number of different type floors such as carpet, asphalt, and a coated floor. A key finding is that the surface itself is a significant factor on the measured profile, i.e. dirt or differing materials can cause false height measurements. Overall the methodology has proved a successful real time solution for creating a point cloud of the floor surface.

Probing hot gas around luminous red galaxies through the Sunyaev–Zel’dovich effect

ABSTRACT We construct the mean thermal Sunyaev–Zel’dovich (tSZ) Comptonization y-profile around luminous red galaxies (LRGs) in the redshift range 0.16 < z < 0.47 from the Sloan Digital Sky Survey Data Release 7 using the Planck y-map. We detect a significant tSZ signal out to ∼30 arcmin, which is well beyond the 10 arcmin angular resolution of the y-map and well beyond the virial radii of the LRGs. We compare the measured profile with predictions from the cosmo-OWLS suite of cosmological hydrodynamical simulations. The best agreement is obtained for models that include efficient feedback from active galactic nuclei, over and above feedback associated with star formation. We also compare our results with predictions based on the halo model with a universal pressure profile giving the y-signal. The predicted profile is consistent with the data when using stacked weak lensing measurements to estimate the halo masses of the LRGs, but only if we account for the clustering of neighbouring haloes via a two-halo term.

RkRk material measure

The standard ISO 13565-2 defines the Rk parameters for the functional characterisation of technical surfaces. So far, no particular material measures for the calibration of these parameters have been defined in the international standardization. For the application and the functional behaviour of technical surfaces the Rk parameters however have a critical significance, so there is a demand by the industry to calibrate these parameters as they are increasingly applied for the quality assessment of workpieces. In the present paper, a proposal for suitable material measures is presented. An algorithm is described, which transforms the data of a real measured profile in a way that the exact defined parameters of Rk, Rpk and Rvk are equated. The material measures geometry corresponds to its later application and the target parameters are almost freely selectable. The approach for transforming surface profile data with the aid of the Abbott curve is introduced generically, solves an inverse problem and considers the influences from the manufacturing and measuring process. The designed material measure is manufactured with the aid of ultra-precision turning. In matters of the aspired industrial application, comparison measurements are carried out in order to examine the practical abilities of the material measure and the repeatability of the approach is proven.

A Mathematical Model on Macro-Segregation Formation for Popular Bloom Continuous Casting Process

A segmented 3-D coupled electromagnetic-thermal solute transportation model, aimed to better understand the macro-segregation formation in the strand during a popular continuous casting (CC) process, has been developed. Based on the model validation by industrial tests, the effect of M-EMS and F-EMS running parameters on the segregation distribution were subsequently carried out. It is shown that the simulated solute segregation profile in the W-shape along the casting thickness direction is in a good agreement with the measured profile. In the initial solidification shell with thickness in 0.020 m, the solute segregation degree changes from a positive value to a negative with the increasing distance from strand surface because of the washing effect induced by the impact flow from the nozzle side port and M-EMS. Here, the minimum degree of carbon segregation decreases from 0.976 to 0.875 with the increasing stirring current from 100A to 550A. As the stirring current of F-EMS decreases from 630A to 200A, the minimum segregation degree locating at 0.109 m distance from strand surface increases from 0.805 to 0.967. The carbon segregation degree at the strand center first decreases from 1.10 to the minimum value of 1.06 at the case of 350 A/4 Hz because of the concentration equilibrium for the local decreasing negative segregation induced by F-EMS, and then increases to 1.16 due to the local poor stirring.