Roughness Depth Research Articles

Estimation of skin surface roughness in vivo based on optical coherence tomography combined with convolutional neural network.

The texture of human skin is influenced by both external and internal factors, and changes in wrinkles can most directly reflect the state of the skin. Skin roughness is primarily used to quantify the wrinkle features of the skin. Therefore, effective and accurate quantification of skin roughness is essential in skincare, medical treatment, and product development. This study proposes a method for estimating the skin surface roughness using optical coherence tomography (OCT) combined with a convolutional neural network (CNN). The proposed algorithm is validated through a roughness standard plate. Then, the experimental results revealed that skin surface roughness including arithmetic mean roughness and depth of roughness depends on age and gender. The advantage of the proposed method based on OCT is that it can reduce the effect of the skin surface's natural curvature on roughness. In addition, the method is combined with the epidermal thickness and dermal attenuation coefficient for multi-parameter characterization of skin features. It could be seen as a potential tool for understanding the aging process and developing strategies to maintain and enhance skin health and appearance.

The Effect of Gastric Acid and Material Type on the Surface Roughness of Additive and Subtractive Manufacturing Resins.

The aim of this study is to examine the effect of gastric acid on the surface roughness of additive and subtractive manufacturing resin. In this study, two subtractive manufacturing CAD-CAM resin nanoceramic (CerasmartTM270 (CS), LavaTM Ultimate (LU)) and two additive manufacturing 3D printing permanent resin (VarseoSmile Crownplus (VSP), Crowntec (CT)) was used. CS and LU samples were turned into 10 mm diameter cylinders with a scraper and cut into 2 mm slices on the cutting device. CT and VSP samples were produced on a 3D printer (2mm thickness-10mm diameter) (n:15). All samples were exposed to a cycle of 60 seconds of gastric acid, 5 seconds of distilled water, and 30 minutes of artificial saliva, 6 times a day for 10 days. Surface roughness mean (Ra) and depth (Rz) was measured with a contact profilometer at baseline and after gastric acid cycling. Data were analyzed using SPSS (22.0), One way ANOVA, post-hoc Tukey's and Independent-t test (p <.05). Ra-Rz values of CT and VSP were significantly higher than CS and LU at baseline and after the gastric acid cycle (p <.05). After the gastric acid cycle, the Ra-Rz values of all materials increased significantly compared to the baseline (p <.05) but the Ra values of all materials were at a clinically acceptable level (<0.2µm). Although additive manufacturing 3D printing permanent resins offered higher roughness values, they weren't at a clinically unacceptable level. Therefore, they can be an alternative to subtractive manufacturing CAD-CAM resin nanoceramics.

Explainable AI based Predictions for Workpiece Quality

It is well known that sound emissions of drilling and milling machines can be used to predict process and work piece quality. Deep Learning models have successfully been applied for that task. However, artificial neural networks are perceived as black boxes as the inference mechanisms of the network are not transparent. In this paper we present a Convolutional Neural Network trained on audio data with which process and product quality of a milling process can be controlled. The model was trained on 10-second audio snippets recorded from a milling machine that were converted into spectrograms. The trained model classifies the drilling process and predicts the expected workpiece quality. Additionally, rough estimates of the center rough and average roughness depth values are predicted. Moreover, we apply the Explainable AI methods that produce explanations by highlighting sections of the spectrogram that were relevant for the prediction. The spectrograms enriched with the explanations provide insights into the decision making process of the deep learning model in a human interpretable form. Patterns of how and why of a prediction become visible. Areas considered relevant by the model can be compared to the expectations of the human user. Through this explanation component, the model is not only able to make predictions but also to increase trust in the system which is an important aspect of acceptance of AI based quality assurance.

Optimizing the diamond wire sawing of polycrystalline silicon: An experimental approach

This study aims to determine the optimized cutting conditions for diamond wire sawing of polycrystalline silicon (poly-Si) wafers using a laboratory machine-tool that employs continuous cutting movement and reach cutting conditions similar to those in the industry. The experimental cutting was carried out following a central composite design, varying the wire cutting speed (vc) and feed rate (vf). A response surface methodology was employed to find the optimized cutting conditions for minimum surface roughness and subsurface micro-crack depth of the as-sawn poly-Si wafer. The results showed that the as-sawn poly-Si exhibited ductile scratches and fragile fractures in its surface morphology, with high vc and low vf resulting in a smooth surface. The response surfaces indicated that increasing vf led to increased Ra and Rq values, while increasing vc reduced them. Median micro-cracks were slightly inclined in the subsurface region, with the response surface indicating that their depth reduced with increasing vc and decreasing vf. The vf/vc ratio significantly affected surface integrity, with a lower vf/vc ratio being more suitable for reaching a smoother surface and shallower subsurface damage. The following material removal mechanisms was identified: optimal ductile region, ductile-to-brittle transition, brittle-ductile mixture region, and brittle region. Simulations using the response surface models indicated minimum values of Ra = 0.35 μm, Rq = 0.48 μm and SSD = 3.29 μm. Thus, this study provides a processing parameter window for diamond wire sawing of poly-Si wafers, which could be useful for both the photovoltaic and microelectronic industries.

How to achieve nanometer flat surfaces: Pulsed electrochemical machining of bulk metallic glass

The Bulk Metallic Glass (BMG) Vitreloy 105 (Zr52.5Ti5Ni14.6Cu17.9Al10) as well as two crystalline reference materials of the same composition were machined with Pulsed Electrochemical Machining (PECM). One reference material was nano crystalline with an average grain size of 11 nm and the second one was a fine grain crystalline sample with an average grainsize of 110 nm. The goal was to achieve maximum surface quality in terms of roughness by utilizing a readily available industrial process. Samples were characterized by tactile profilometer, atomic force microscopy and electron microscopy methods. The results show superior surface quality of the amorphous samples over the reference materials with an average roughness depth as low as 1 nm. The observed dissolution mechanism of the BMG differs from the reference materials -as in contrast to the crystalline alloys that show a passive layer formation - no such surface layer other than the native oxide could be observed. The PECM procedure is found to be a promising post-processing step for BMGs with a resulting surface that can face even the most challenging surface quality requirements.

Evaluation of the Loss of Surface Roughness Following the Use of Four Different Instruments for Mechanical Debridement of Dental Implants: An In-vitro Pilot Study

To compare the dental implant surface properties such as mean surface roughness, roughness depth, and the surface loss produced by different prophylactic instrument types. Twenty-four surfaces of twelve dental implants were treated using titanium curettes, titanium-coated curettes, an air abrasion unit, and titanium brushes. The dental implants were inserted partially into a Styrofoam base, exposing one-third to simulate cases of peri-implantitis. The exposed surface was coated with artificial dental calculus (ADC) and divided into four groups for treatment. The arithmetic mean surface roughness (Ra) and the mean roughness depth (Rz) were assessed using the confocal microscope, and the surface loss (SL) area was calculated from the scanning electron microscopic images using an image analysis software. The Ra value varied between 1.08 to 0.29 µm, the Rz value between 10.3 to 70.5 µm, and the mean surface loss area between 154 to 9410 µm2. The One-way ANOVA analysis showed a statistically significant difference between the four groups (P < 0.05). The air abrasion unit showed the highest mean roughness value of 1.08 ± 0.14 µm, mean roughness depth of 70.5 ± 2.21 µm, and a minor surface area loss of 154 ± 132 µm2. In comparison, the titanium brushes showed the least Ra and Rz of 0.29 ± 0.05 µm and 10.3 ± 2.32 µm, respectively, whereas the titanium-coated curettes showed the highest loss of surface area 9410 ± 91.6 µm2. The air abrasion unit was shown to have the least detrimental effect on the implant surface when removing the artificial dental calculus compared to the other three methods.

Parametric Analysis and Optimization on Fiber Laser Micro-Milling on AZ31 Magnesium Alloy

One of the proficient machining technologies to create micro-features in a variety of materials is the laser micro-milling process. This procedure involves irradiating a highly concentrated laser beam on the sample and performing laser cutting at various cutting patterns to change the surface conditions and enhance the characteristics of that surface tribology. In this work, an effort has been made to mill magnesium alloy (AZ31) material using a laser. The pulse frequency, laser beam power, cutting speed, number of passes, and transverse feed are among the different process variables taken into account for the current research effort. Measured results include depth of cut and surface roughness. To ensure the validity of the established empirical models, this paper also presents experimental data. Several surface plots have been used to examine the test data. To get the lowest values of surface roughness and depth of cut, multiperformance optimization is also utilized. The influence of process factors on response has also been examined using optical microscopic images. Gray relational analysis approach is also applied to obtain the multiobjective optimization parametric combination and based on the calculated results of gray relational grade, it is revealed that improvement in the value of gray relational grade at predictive setting is 0.054 compared to the initial parametric combination.

Effect of Laser Parameters on Surface Texture of Polyformaldehyde and Parameter Optimization

This research aimed to investigate the influence of laser process parameters on the surface texture of Polyformaldehyde (POM) and to improve its processability and process predictability. A comparative experiment and analysis involving multiple processing parameters, including laser power, scanning speed, and pulse width, were conducted on POM. Statistical prediction models of laser processing POM were established among the laser power, scanning speed, pulse width, texture depth, surface roughness at the bottom of texture, and multi-objective optimization and experimental verification of process parameters were carried out based on the grey-Taguchi analysis method. Experimental results show that the laser power and scanning speed significantly affect the texture depth. Higher laser power and lower scanning speed are conducive to forming depth. The surface roughness at the bottom of the texture increases with the increase in scanning speed and shows a tendency to rise and then fall as the laser power increases. The surface roughness and texture depth obtained under the optimal process parameters(A5B1C1) are 1.373 μm and 466.891 μm, respectively, which were reduced by 10.08 % and increased by 3.42 % compared with the minimum surface roughness and maximum depth in the orthogonal experiments. The validation experiments of the prediction model show that it can meet the reliability requirements, and the errors of the predicted values of depth and surface roughness are 1.86 % and 7.60 %, respectively. The above research provides theoretical and experimental support for the precise control of surface texture prepared by laser processing POM.

Parametric investigation of wire-EDM parameters for micro channel as a foundation of high-quality micro needle array fabrication

Micro channels are widely used in microfluidics, and medical science for the extraction of DNA, electrophoresis, and blood protein analysis. In the current work, the wire electrical discharge machining (WEDM) process was used to fabricate micro channels on the stainless steel 316 (SS316) substrate. To check the feasibility of fabricating high-quality micro channels and thereafter micro-scale structures with the WEDM process the effect of different process parameters such as pulse-off time, pulse-on time, servo gap reference voltage and wire feed rate were investigated. The quality attributes taken were namely surface roughness of the channel base, overcut, micro channel depth, and material removal rate (MRR). The pulse-on time significantly affects surface roughness and MRR. The servo gap reference voltage is the key process parameter affecting the overcut and micro channel depth. It was observed from the parametric study that 15 µs pulse-on time, 35 µs pulse-off time, 17 v servo gap reference voltage, and 8 m/min wire feed rate are the optimum levels for getting high MRR, low surface roughness, less overcut and high micro channel depth. Additionally, the topographical, morphological, surface, and sub-surface characterization were also carried out to assess the surface integrity and extent of thermal damage caused by the WEDM process. With the optimum combination of process parameters a 6 × 6 micro needle array was successfully fabricated on the same substrate using micro channels as a basis of the fabrication process for the first time using the WEDM process.

Effects of chemical action of polishing medium on the material removal of SiC

The chemical action mechanism in the chemical mechanical polishing of SiC substrate remains elusive, which has great limitations on the selection of polishing solution and polishing parameters. In this paper, the cutting process of unreacted SiC (U–SiC) and the SiC reacted with H2O (R-SiC-H2O) and H2O2 (R-SiC-H2O2) was studied with an individual diamond abrasive particle by molecular dynamics simulation. The influence of chemical reaction and cutting speed on the material removal of SiC was explored by focusing on the removal rate, surface quality, machining temperature and machining stress. The simulation results showed that the number of removed atoms increased, and the surface roughness and subsurface damage depth decreased for SiC at the same cutting speed after the chemical action. Although the number of removal atoms increased with the increase of cutting speed, the surface roughness and subsurface damage depth increased at the same time. The effects of the polishing medium on the material removal process for SiC can be attributed to the decrease of surface hardness and Si–C bonding energy after the reaction of the polishing medium and SiC. The results provide a guidance for the selection of chemical mechanical polishing systems and machining parameters.

An Experimental Parametric Optimisation for Laser Engraving and Texturing to Integrate Zirconia Ceramic Blocks into Stainless Steel Cutlery: A State-of-the-Art Aesthetically Improved Perspective.

Cutlery and flatware designs are an everchanging phenomenon of the manufacturing industry. Worldwide hospitality businesses demand perpetual evolution in terms of aesthetics, designs, patterns, colours, and materials due to customers' demands, modernisation, and fierce competition. To thrive in this competitive market, modern fabrication techniques must be flexible, adoptive, fast, and cost effective. For decades, static designs and trademark patterns were achieved through moulds, limiting production to a single cutlery type per mould. However, with the advent of laser engraving and design systems, the whole business of cutlery production has been revolutionised. This study explores the possibility of creating diverse designs for stainless steel 304 flatware sets without changing the entire production process. The research analyses three key laser process parameters, power, scanning speed, and number of passes, and their impacts on the resulting geometry, depth of cut, surface roughness, and material removed. These parameters are comprehensively studied and analysed for steel and zirconia ceramic. The study details the effects of power, scanning speed, number of passages, and fluence on engraved geometry. Fluence (power*number of passages/scanning speed) positively influences outputs and presents a positive trend. Medium power settings and higher scanning speeds with the maximum number of passages produce high-quality, low-roughness optimised cavities with the ideal geometric accuracy for both materials.

Efficiency of Virucidal Disinfectants on Wood Surfaces in Animal Husbandry.

The aim of this study was to test the inactivation of viruses on germ carriers of different types of wood using a disinfectant in order to assess the biosafety of wood as a building material in animal husbandry. The laboratory disinfectant efficacy tests were based on German testing guidelines and current European standards. Five different types of wood germ carriers, i.e., spruce (Picea abies), pine (Pinus sylvestris), poplar (Populus sp.), beech (Fagus sylvatica) and Douglas fir (Pseudotsuga menziesii), were inoculated with enveloped or non-enveloped viruses and then treated with one of three different disinfectants. The results revealed that intact, fine-sawn timber with a low roughness depth can be effectively inactivated. Peracetic acid proved to be the most effective disinfectant across all tests. Regardless of the pathogen and the type of wood, a concentration of 0.1% of the pure substance at a temperature of 10 °C and an exposure time of one hour can be recommended. At a temperature of -10 °C, a concentration of 0.75% is recommended. The basic chemicals formic acid and glutaraldehyde demonstrated only limited effectiveness overall. The synergistic effects of various wood components on the inactivation of viruses offer potential for further investigation. Disinfectant tests should also be conclusively verified in field trials to ensure that the results from standardised laboratory tests can be transferred to real stable conditions.

Tenacity of Animal Disease Viruses on Wood Surfaces Relevant to Animal Husbandry

The aim of this study was to analyse the hygienic suitability of wood often used in animal husbandry. To this end, the inactivation of viruses (Enterovirus E as a surrogate for non-enveloped viruses and Newcastle disease virus as a surrogate for enveloped viruses) on germ carriers consisting of various types of wood was studied over an extended period to assess the biosafety of wood as an agricultural building material. The study was designed to assess the intrinsic biocidal activity of the wood itself, without the use of a disinfectant. The laboratory tests were based on German test guidelines and current European standards. Five different types of wood germ carriers, i.e., spruce (Picea abies), pine (Pinus sylvestris), poplar (Populus sp.), beech (Fagus sylvatica) and Douglas fir (Pseudotsuga menziesii), as well as stainless-steel carriers, were inoculated with enveloped and non-enveloped viruses and stored for up to four months, and the remaining infectivity of the viruses was continuously assessed. The results showed that intact, finely sawn timber with a low depth of roughness had an inactivating effect on the viruses up to 7.5 decadal logarithmic levels. For the non-enveloped virus, inactivation was fastest on Douglas fir wood, with the target reduction for effective inactivation (reduction by factor 4.0 log10) being achieved after two weeks, and for the enveloped virus on pine wood, it was already achieved from the day of drying. The hygienic effects of the wood carriers may be due to their hygroscopic properties and wood constituents. These effects offer potential for further investigation, including tests with other wood species rich in extractives.

Experimental study on abrasive flow finishing of narrow inner cavity of alumina-dispersed copper absorber

Given the difficulties in processing and detecting the narrow and deep inner cavities of the diffusive copper absorber used by the High Energy Photon Source (HEPS), a regression equation prediction model for surface roughness and material removal depth based on abrasive flow machining was proposed through mixed-level orthogonal experiments. The influences of machining area pressure, machining cycle number, and abrasive mesh number on surface roughness and material removal were revealed. Subsequently, abrasive flow machining verification experiments were conducted on the narrow and deep inner cavities of the absorber, showing that the experimental results were within 15% error compared to the model predictions. After abrasive flow machining, the roughness decreased from about 4.4 μm to around 0.6 μm, significantly improving the surface quality of the workpiece. These research findings can provide a theoretical basis and technical support for the optical finishing of workpieces with narrow and deep variable cross-section inner cavities.

Tribological Behavior of GTL Base Oil Improved by Ni-Fe Layered Double Hydroxide Nanosheets

The layered double hydroxide (LDH) has been practically applied in the field of tribology and materials science due to its unique physicochemical properties, weak bonding, flexible structural composition, and adjustable interlayer space. In this work, a series of ultrathin and flexible composition of Ni-Fe LDH samples were prepared via a cost-effective room-temperature co-precipitation process. Then, they were mechanically dispersed into GTL base oil and their lubricating performance were tested by a four-ball tribometer. It is found that the variation of Ni-Fe ratio of Ni-Fe LDH has a great influence on the improvement of lubricating performance of GTL base oil. At the same concentration (0.3 mg/mL), the Ni-Fe LDH with Ni/Fe ratio of 6 was demonstrated to exhibit the best lubricating performance and the AFC, WSD, the wear volume, surface roughness and average wear scar depth decreased 51.3%, 30.8%, 78.4%, 6.7% and 50.0%, respectively. SEM-EDS and X-ray photoelectron spectra illustrated that the tribo-chemical film consisting of iron oxides and NiO with better mechanical properties formed and slowly replaced the physical film, which resists scuffing and protect solid surface from severe collisions.

High-performance grinding of ceramic matrix composites

Ceramic matrix composites (CMCs) are highly promising materials for the next generation of aero-engines. However, machining of CMCs suffers from low efficiency and poor surface finish, which presents an obstacle to their wider application. To overcome these problems, this study investigates high-efficiency deep grinding of CMCs, focusing on the effects of grinding depth. The results show that both the surface roughness and the depth of subsurface damage (SSD) are insensitive to grinding depth. The material removal rate can be increased sixfold by increasing the grinding depth, while the surface roughness and SSD depth increase by only about 10%. Moreover, it is found that the behavior of material removal is strongly dependent on grinding depth. As the grinding depth is increased, fibers are removed in smaller sizes, with the fiber length in chips being reduced by about 34%. However, too large a grinding depth will result in blockage by chip powder, which leads to a dramatic increase in the ratio of tangential to normal grinding forces. This study demonstrates that increasing the depth of cut is an effective approach to improve the machining efficiency of CMCs, while maintaining a good surface finish. It provides the basis for the further development of high-performance grinding methods for CMCs, which should facilitate their wider application.

Entropic velocity distribution for sediment-laden flows with a modified dip estimation model at data-scarce river sites

ABSTRACT This study proposes an entropic velocity-distribution and dip-position (y max) model for sediment-laden (SL) flows. Unlike previous studies, the proposed entropic distribution incorporates the effect of suspended sediment (SS) and y max, to improve velocity predictions near bed and water surface in SL flows. A new dampened mixing length for SL flows is proposed in terms of SS concentration. Moreover, the effect of channel bed roughness (k s), slope (S), SS, width (B) and flow depth (H) on y max is studied. Further, a comprehensive model for y max is proposed as a bivariate function of B/H and k s/H for natural channels. A comparative analysis is presented with the existing models, which shows the proposed equations provide higher accuracy with fewer parameters and a better representation of physical processes in SL flows. Subsequently, the proposed equations are applied at three gauged sites (Mahanadi River, India), showing their suitability to obtain velocity at data-scarce river sites.

Effect of polishing versus glazing of CAD-CAM ceramics on wear and surface roughness of opposing composite resin

Background: This study aimed to assess the effect of polishing versus glazing of computer-aided design-computer-aided manufacturing (CAD-CAM) ceramics on depth of wear and surface roughness of opposing composite resin. Materials and Methods: This in vitro study was conducted on 40 Z250 composite and 40 CAD-CAM ceramic specimens including Celtra Duo, Vita Mark II, e.max CAD, and Vita Suprinity ceramics. All ceramic specimens were roughened by a fine-grit bur after primary glazing to simulate an adjusted surface in the clinical setting. They were then randomly assigned to two subgroups and underwent reglazing or polishing. All composite and ceramic specimens underwent profilometry after surface treatment and prior to the wear test, and the results were recorded quantitatively. Composite specimens were then subjected to 120,000 wear cycles against ceramic specimens in a chewing simulator, and the depth of wear was measured by a scanner. Data were statistically analyzed by repeated measures two-way analysis of variance (ANOVA) and one-way ANOVA (α = 0.05). Results: Comparison of the surface roughness of composite specimens before and after the wear test revealed significant differences in both glazed Suprinity (P = 0.048) and Vita Mark II (P = 0.026) ceramics groups. The change in surface roughness after the wear test (compared with baseline) was significant in glazed (P = 0.000) and polished (P = 0.013) Vita Mark II and polished Suprinity (P = 0.037) ceramics, but this change was not significant in other ceramics (P &gt; 0.05). The depth of wear after the wear test was not significantly different among the ceramic and composite subgroups (P &gt; 0.05). Conclusion: Assessment of depth of wear and surface roughness of composite specimens showed that the polishing kits of CAD-CAM ceramics can serve as a suitable alternative to reglazing.

Impact of combining dental composite brushes with modeling resins on the color stability and topographic features of composites.

This study explores the effect of using dental brushes with or without metacrylate-based modeling resins on long-term color stability and surface topographies of resin-based composites. This study examined the effects of two variables: (1) the type of brush used (Art brush, Micro-brush, or Mylar strip) and (2) the application of a modeling resin (applied or not applied). The specimens were artificially aged through 10,000 cycles of thermocycling and subsequently immersed in coffee for 30 days. Measurements of color and surface roughness were taken at baseline and after the aging, using a non-contact profilometer for surface roughness and a spectrophotometer for color. Data were analyzed using paired t-tests and one-way ANOVA. Resin-based composites smoothed with dental brushes or micro brushes without modeling resins exhibited lower color change (ΔE) than other groups. Paired t-tests revealed significant differences in average surface roughness (Ra) and valley depth (Rv) for each surfacing technique before and after aging (p ⩽ 0.01). The root means square average of the profile heights (Rq) significantly increased in the control and micro-brush groups (p ⩽ 0.01). In conclusion, the use of brushes in resin-based composites placement does not increase the susceptibility to staining. Instead, the inclusion of resin modeling contributes to discoloration over time.

Statistical modelling of depth milling in Ti-6AL4V using abrasive water jet machining

Multi-objective grey relational analysis optimization technique and multiple regression analysis were employed to determine the optimum values for depth of cut, surface roughness ( Ra), and kerf at entry and exit ([Formula: see text] and [Formula: see text]), for abrasive waterjet machining of Ti6AL4V materials. This method highlights a new process to extend the grey relational analysis technique for determining the optimum conditions for obtaining the best quality characteristics. The input parameters of the study were water pressure ( Wp), transverse speed ( Ts), abrasive mass flow rate ( Amf), abrasive orifice size ( Aos), nozzle/orifice diameter ratio ( N/Odia). The experiments were conducted as per the Taguchi-based L27 orthogonal array. The grey relational analysis technique found that Ts was the most significant parameter on the combined outputs. The regression models developed had an R2 of 81.58%, 79.79%%, 77.20%, and 74.39% for depth of cut, Ra, [Formula: see text] and [Formula: see text], respectively. Additionally, the analysis of variance showed that Wp and Aos had a significant influence on the output parameters. The predicted values were found to be reasonably close with the experimental values, and the maximum average deviation was 8.15% for [Formula: see text].