Measurement uncertainty of surface roughness measurement

Detection of skin wrinkles and quantification of roughness using a novel image processing technique from a dermatoscope device

OBJECTIVE

Cutaneous relief analysis is crucial in the development of new skincare products, as well as in the evaluation of dermatological treatments. The analysis can be performed by qualitative or quantitative methods. We propose a new algorithm to detect wrinkles and quantify skin roughness by image processing from a dermatoscope.

METHODS

A clinical study was carried out with 33 research participants, and images were collected with the dermatoscope and PRIMOS equipment for wrinkle evaluation at two different times: Day 0 (D0) and 45 days (D45) after the use of a dermocosmetic product. Later, a new algorithm was developed to detect wrinkles in the acquired images by applying filters and image transformations that generate a segmented image highlighting the wrinkles. A roughness calculation method is proposed from the pixels belonging to wrinkles.

RESULTS

Correlation between the values obtained by the PRIMOS equipment and the proposed system was verified. No correlation was found for data obtained at D0; however, there was correlation at time D45 by Spearman's similarity coefficient. By comparing roughness between times D0 and D45, the treatment was statistically significant for both PRIMOS and the proposed methodology data.

CONCLUSION

The wrinkle detection algorithm, in addition to the roughness calculation, demonstrated a sensitivity comparable to the PRIMOS system in evaluating the effectiveness of the dermocosmetic treatment.

SIGNIFICANCE

Considering the simplicity of the dermatoscope design compared to other established devices such as PRIMOS, the proposed system is promising as an alternative for dermatological evaluations.

Preliminary Testing to Determine the Best Process Parameters for Polymer Laser Sintering of a New Polypropylene Polymeric Material

Polymer laser sintering is an elaborate additive manufacturing technique because it is subject to process parameters and material properties. In this regard, each polymeric material necessitates a different set of process conditions. To this end, testing was done to determine the most suitable process parameters for a new commercially available polymer (Laser PP CP 60), from Diamond Plastics GmbH. It was established that the material requires slightly different settings from those provided by the supplier for the values for the removal chamber temperature, building chamber temperatures, and laser power to achieve the best mechanical properties (ultimate tensile strength). The preliminary testing indicates that the process parameters that yielded the best mechanical properties for the laser PP CP 60 powder were 125°C, 125°C, 0.15 mm, 250 μm, 4500 mm/s, 34.7 W, 1500 mm/s, and 21.3 W for the removal chamber temperature, building chamber temperature layer thickness, hatch distance, scanning speed fill, laser power fill, scanning speed contour, and laser power contour, respectively.

A Review of Methods Used to Reduce the Effects of High Temperature Associated with Polyamide 12 and Polypropylene Laser Sintering

The polymer laser sintering (PLS) process is one of the most promising additive manufacturing (AM) technologies for polymeric materials. However, the technique has challenges because the physical, mechanical, and chemical properties of the polymeric powder deteriorate due to the high temperatures prevailing in the build chamber during manufacture. These high temperatures cause agglomeration of powder, which leads to a decrease in the flowability of powder. There is also a related drop in the coalescence of the powder granules during PLS, which results in porosity that undermines the mechanical integrity of printed parts. Moreover, the viscosity of the melt increases due to cross-linking of molecular chains. This, in turn, increases the tensile strength of the printed components at the expense of the percentage elongation at break. Thus, high prolonged processing temperatures decrease the reusability of polymeric materials used in PLS. In this paper, a review of the studies conducted to investigate ways of reducing the effects of high temperature on polymeric powders is presented.

The Effect of the Feed Direction on the Micro- and Macro Accuracy of 3D Ball-end Milling of Chromium-Molybdenum Alloy Steel

The machining of free form surfaces is one of the most challenging problems in the field of metal cutting technology. The produced part and machining process should satisfy the working, accuracy, and financial requirements. The accuracy can describe dimensional, geometrical, and surface roughness parameters. In the current article, three of them are investigated in the case of the ball-end milling of a convex and concave cylindrical surface form 42CrMo4 steel alloy. The effect of the tool path direction is investigated and the other cutting parameters are constant. The surface roughness and the geometric error are measured by contact methods. Based on the results, the surface roughness, dimensional error, and the geometrical error mean different aspects of the accuracy, but they are not independent from each other. The investigated input parameters have a similar effect on them. The regression analyses result a very good liner regression for geometric errors and shows the importance of surface roughness.