Detailed Surface Research Articles

Structural Transitions of Anionic, Cationic, and Nonionic Surfactant Solutions Confined between Amorphous SiO2 Slabs: Molecular Dynamics Simulations

Adsorption of surfactants of a different nature on solid surfaces has found remarkable enthusiasm in many industrial processes such as enhanced oil recovery, detergency, solubilization, and flocculation/dispersion. Surfactants can interact with solid slabs and alter their surface charge and hydrophobicity, which are essential in interfacial phenomena. Interestingly, the surface charges of amorphous materials are thoroughly different from crystalline materials due to the disordered distribution of surface atoms. Therefore, we performed molecular dynamics simulations to examine the interactions of surfactant solutions with SiO2 surface in detail. To this aim, aqueous solutions of various surfactants were confined between two amorphous SiO2 walls, which were 10 nm apart. The results indicate that the structure of the amorphous solid surfaces is changed substantially due to their interactions with surfactant solutions. The simulation results indicate the presence of the nonionic surfactant aggregates in the bulk solvent, while ionic surfactants without branching, such as SDS, form aggregates that adsorb on the SiO2 surface. The interactions of the confined surfactants with glassy SiO2 slabs change the structure of the surface layer and consequently alter the surface charge density during the simulation, which leads to the separation of cationic and anionic parts of the confined surfactants in the vicinity of amorphous SiO2 slabs.

HIGH RESOLUTION SURFACE RECONSTRUCTION OF CULTURAL HERITAGE OBJECTS USING SHAPE FROM POLARIZATION METHOD

Abstract. Nowadays, three-dimensional reconstruction is used in various fields like computer vision, computer graphics, mixed reality and digital twin. The three- dimensional reconstruction of cultural heritage objects is one of the most important applications in this area which is usually accomplished by close range photogrammetry. The problem here is that the images are often noisy, and the dense image matching method has significant limitations to reconstruct the geometric details of cultural heritage objects in practice. Therefore, displaying high-level details in three-dimensional models, especially for cultural heritage objects, is a severe challenge in this field. In this paper, the shape from polarization method has been investigated, a passive method with no drawbacks of active methods. In this method, the resolution of the depth maps can be dramatically increased using the information obtained from the polarization light by rotating a linear polarizing filter in front of a digital camera. Through these polarized images, the surface details of the object can be reconstructed locally with high accuracy. The fusion of polarization and photogrammetric methods is an appropriate solution for achieving high resolution three-dimensional reconstruction. The surface reconstruction assessments have been performed visually and quantitatively. The evaluations showed that the proposed method could significantly reconstruct the surfaces' details in the three-dimensional model compared to the photogrammetric method with 10 times higher depth resolution.

Tiled Characteristic Maps for Tracking Detailed Liquid Surfaces

AbstractWe introduce tiled characteristic maps for level set method that accurately preserves both thin sheets and sharp edges over a long period of time. Instead of resorting to high‐order differential schemes, we utilize the characteristics mapping method to minimize numerical diffusion induced by advection. We find that although a single characteristic map could be used to better preserve detailed geometry, it suffers from frequent global re‐initialization due to the strong distortions that are locally generated. We show that when multiple localized tiled characteristic maps are used, this limitation is constrained only within tiles; enabling long‐term preservation of detailed structures where little distortion is observed. When applied to liquid simulation, we demonstrate that at a reasonably amount of added computational cost, our method retains small‐scale high‐fidelity (e.g., splashes and waves) that is quickly smeared out or deleted with purely grid‐based or particle level set methods.

EFFECTS OF MACHINING PARAMETERS ON TOOL LIFE

Cutting tools, which are used extensively in machining, are expected to have high performance and longer service life. Tool life term defines the time period between the starting of the cutting tool and the sharpening of the tool so that the tool is actively used. According to international standards, tool deterioration by wear is a specific criterion used to determine tool life. In this study, the effects of cutting parameters on the cutting performance and tool life of standard end mills with diameters Ø6, Ø8, Ø10, Ø12 which are used extensively in the die-making industry, were investigated. Detection of cutting-edge wear conditions was achieved by conducting detailed surface observations with a high-resolution camera of a three-dimensional (3D) digital microscope

LaplacianFusion

We propose LaplacianFusion , a novel approach that reconstructs detailed and controllable 3D clothed-human body shapes from an input depth or 3D point cloud sequence. The key idea of our approach is to use Laplacian coordinates, well-known differential coordinates that have been used for mesh editing, for representing the local structures contained in the input scans, instead of implicit 3D functions or vertex displacements used previously. Our approach reconstructs a controllable base mesh using SMPL, and learns a surface function that predicts Laplacian coordinates representing surface details on the base mesh. For a given pose, we first build and subdivide a base mesh, which is a deformed SMPL template, and then estimate Laplacian coordinates for the mesh vertices using the surface function. The final reconstruction for the pose is obtained by integrating the estimated Laplacian coordinates as a whole. Experimental results show that our approach based on Laplacian coordinates successfully reconstructs more visually pleasing shape details than previous methods. The approach also enables various surface detail manipulations, such as detail transfer and enhancement.

The Effect of Hypochlorous Acid Disinfectant on the Reproduction of Details and Surface Hardness of Type III Dental Stone.

Introduction Gypsum products have been used for many years in dentistry. They are used to make casts that are used in different dental laboratory procedures. It is considered a source of contamination because it comes in contact with blood and saliva that are found on dental impressions. Because it is difficult to make sure that every impression brought to the dental laboratory has been cleanedand because cleaning impressionsis a complicated process that can lead to problems because of the way impression materials are made, cleaning the cast has become a key part of preventing infections. For this study, we used two ways (immersion and spray) to apply a hypochlorous acid (HOCl) disinfectant solutionto type III dental stone to see how they affected the stone's surface hardness and its ability to show surface details accurately. Materials and methods A total of 100 samples of type III dental stone, 50 samples for each test, which include the reproduction of detailtest and surface hardness test, were prepared and randomly divided into five groups, 10 samples for each test group, which include group A (control), group B (immersion in 200 ppm HOCl disinfectant for five minutes), group C (spraying with 200 ppm HOCl disinfectant for five minutes), group D (immersion in 0.6% sodium hypochlorite (NaOCl) disinfectant for five minutes), and group E (spraying with 0.6% NaOCl disinfectant for five minutes). Results The results showed that all the samples had met the reproduction of detailtest requirement after disinfection with HOCl, while a significant reduction in the surface hardness of type III stone samples was also shown. Conclusion The less undesirable effects of HOCl disinfectant solution on the surface hardness of type III dental stone when compared to sodium hypochlorite, as well as the absence of adverse effects on detail reproduction, made the HOCl disinfectant solution a good choice for dentists and dental laboratory personnel for cast disinfection and contamination control.

Accuracy Assessment of Direct Georeferencing for Photogrammetric Applications Based on UAS-GNSS for High Andean Urban Environments

Unmanned Aircraft Systems (UAS) are used in a variety of applications with the aim of mapping detailed surfaces from the air. Despite the high level of map automation achieved today, there are still challenges in the accuracy of georeferencing that can limit both the speed and the efficiency in mapping urban areas. However, the integration of topographic grade Global Navigation Satellite System (GNSS) receivers on UAS has improved this phase, leading to a reach of up to a centimeter-level accuracy. It is therefore necessary to adopt direct georeferencing (DG), real-time kinematic positioning (RTK)/post-processed kinematic (PPK) approaches in order to largely automate the photogrammetric flow. This work analyses the positional accuracy using Ground Control Points (GCP) and the repeatability and reproducibility of photogrammetric products (Digital Surface Model and ortho-mosaic) of a commercial multi-rotor system equipped with a GNSS receiver in an urban environment with a DG approach. It was demonstrated that DG is a viable solution for mapping urban areas. Indeed, PPK with at least 1 GCP considerably improves the RMSE (x: 0.039 m, y: 0.012 m, and z: 0.034 m), allowing for a reliable 1:500 scale urban mapping in less time when compared to conventional topographic surveys.

A Bioinspired Triple‐Hierarchical Superhydrophobic Surface with Exceptional Robustness to Water Impingement

Bioinspired surfaces have great potential for self‐cleaning, condensation acceleration, and drag reduction. However, manufactured biomimetic surfaces typically feature only one or occasionally two length scales of surface topography and do not fully recapitulate the structure and function of natural textures. Herein, a triple‐hierarchical superhydrophobic surface (TriSS) inspired by water‐repellent lotus leaves is introduced, which consist of arrays of microprotrusions with various sizes, grooves between the protrusions, and a covering of nanoscale hairs. The TriSS surface is manufactured by forming an array of microdomes through photolithography and thermal reflow. These microstructures are transferred, by casting, to an elastomer, which is then augmented with surface wrinkles by the relaxation of biaxial stress in an oxidized surface layer. Conformal growth of a nanoporous zinc oxide film and fluorosilanization adds further surface detail. The TriSS surface achieves a sessile water contact angle up to 174.3 ± 0.3° and contact angle hysteresis down to 9.9 ± 0.3° via the very limited liquid–solid contact enabled by the surface topography. The surface also captures and retains a stable air layer, which resists water impingement even when submersed to 20 cm depth for more than 200 h. The TriSS process offers a scalable route to water repellence in industrial applications.

A methodology for shape matching of non-rigid structures based on integrated graphical information

Shape matching is a long-studied problem and lies at the core of many applications in statistical shape analysis, virtual reality and human–computer interaction. This paper presents an automatic dense correspondence method to match the mesh vertices of two 3D shapes under near-isometric and non-rigid deformations. The goal is achieved by combining three types of graphic structure information. The method includes three major steps: first, we describe the vertices based on three types of graphical information, Euclidean structure information, Riemannian structure information, and conformal structure information; second, the match between two shapes is formulated as an optimization problem and a novel objective function is proposed; third, we resolve the optimal solution by using the projected descent optimization procedure to solve the objective function. The method is tested on various shape pairs with different poses, surface details, and topological noises. We demonstrate the performance of our approach through an extensive quantitative and qualitative evaluation on several challenging 3D shape matching datasets where we achieve superior performance to existing methods.

Tailored Pd/C bifunctional catalysts for styrene production under an ethylbenzene oxidative dehydrogenation assisted direct dehydrogenation scheme

Rational design of efficient ethylbenzene (EB) dehydrogenation catalyst and reaction route is the key scientific challenge for styrene (ST) formation. We reported here a dual-path dehydrogenation (DPDH) route to efficiently convert EB to ST on a Pd/hollow nanocarbon spheres bifunctional catalyst, which exhibited ST formation rate up to 7.11 mmol g−1 h−1 with > 99 % selectivity. Detailed kinetic, isotopic and surface reaction analysis and corresponding DFT calculation suggested that the relatively high intrinsic catalytic activity originated not only from the single atomically dispersed Pd-based coordination structure but also the unique oxidative dehydrogenation (ODH) assisted direct dehydrogenation (DDH) reaction route. In this route, the small amount of H2O produced from ODH effectively lowered the energy barrier for hydrogen generation/desorption via a proton transfer process promoting the DDH process. The present work shed light on the rational design of catalyst and routes for highly efficient alkane dehydrogenation reaction systems.

Effect of Machining Directions on Surface Integrity of AISI 1018 Steel in a Face Milling Process

This study analyses the effect of machining directions on surface integrity of AISI 1018 steel by performing a face milling operation using the zag toolpath strategy; undertaking a detailed surface roughness check of the machined surface in the cutting and feed directions; studying the microstructure of the as-received workpiece and subsurface of the machined part in the cutting and feed directions in 2% Nital etching; and comparing the grain size before and after the cutting process. Results show that surface roughness values were minimal when measurements were conducted at the middle of the machined surface. Also, surface roughness values were higher in the feed direction than in the cutting direction by 13% due to the presence of feed marks which were clearly visible on the machined surface. The grains at the top machined surface were deformed, elongated, and oriented in the cutting direction as a result of plastic deformations experienced in the machining process, while the grains were also elongated and disoriented in the feed direction. Surface damages caused by the cutting tool’s engagement of the workpiece were clearly seen at the side of the machined surface’s edge. The average grain size value before machining was higher than the average grain size value after machining by 27%, attributed to the plastic deformation of the grain structure as a result of machining. This study has provided an in depth knowledge and understanding of the influence of plastic deformation due to machining on surface roughness and microstructure of the machined part.

Heat transfer enhancement of the f-MWCNT- Fe2O3/Water hybrid nanofluid with the combined effect of wire coil with twisted tape and perforated twisted tape

The impact of various variables on thermal conductivity and rheological behavior, such as nano particle weight concentration and temperature, and also the cumulative effects of coil ratio (CR = 3, 4) of wire coil insert and twist ratio (TR = 3, 4 and 5) of twisted tape (TT) and perforated twisted tape (PTT) on heat transfer coefficient and friction factor characteristics is explored. Nanofluids containing particles with weight percentages of 0.01%, 0.02%, and 0.03% were produced by dispersing functionalized multi-walled carbon nanotubes (f-MWCNTs) 60% by weight and Fe2O3 nanoparticles 40% by weight in distilled water and stabilizing them with an ultrasonic probe. The KD-2 Pro thermal analyzer and Rheometer are used to measure the thermal conductivity and viscosity of the hybrid nanofluids. The impact of various factors on the heat transfer and pressure drop is investigated, including Reynolds number, nanoparticle concentration, TR and CR of TT, PTT and WC. The findings clearly show that higher content of nanoparticles increases heat transfer as well as pressure drop. In contrast to the base coolant, the enhancement in heat transfer and friction factor is 21.66%–31.66% and 1.14 times, respectively. In comparison to a plain tube passing through 0.03 wt % hybrid nanofluid, the enhancements in heat transfer and friction are 32.31%–94.03%, 43.94%–141.07%, and 1.09 times, 1.13 times for the combined effect of TT and PTT having wire insert at ratio's of twist and coil are 3, respectively. Furthermore, UV–vis spectroscopy is being used to assess the stability of the prepared nanofluids, which is found to be acceptable. FESEM is used to determine the detailed surface properties.

Dynamics of primary structure coupled with single-sided vibro-impact nonlinear energy sink

In this paper, we consider a two-mass 2-DOF vibro-impact system, consisting of a linear oscillator, called the primary structure, and an impact damper attached to it. A damper with a small mass hits a wall rigidly connected to the primary structure. This scheme corresponds to the scheme of single-sided vibro-impact nonlinear energy sink – SSVI NES. It is shown that even a light damper can reduce the amplitude and velocity of the primary structure oscillatory movement, that is, decrease its energy. Further optimization of damper parameters should improve this effect. The impact simulation using Hertz’s nonlinear contact force makes it possible to take into account the mechanical characteristics of all colliding surfaces in more detail. The introduction of the initial distance between the primary structure and the damper into the calculation scheme makes it possible to take into account the impact between bodies and see when this impact is absent.

Prediction of surface morphology and reflection spectrum of laser-induced periodic surface structures using deep learning

Laser-induced periodic surface structures have been extensively explored as an enabling tool for fabricating various optical surfaces because the resulting surface ripples can effectively modify surface reflectance. Here, we propose a deep-learning-based model for predicting high-quality surface scanning electron microscopy (SEM) images with detailed surface morphology corresponding to unexplored process conditions. In addition, the reflectance value at 550 nm and reflection spectra from the generated (or original) SEM images were predicted. To obtain training data, stainless steel 304 specimens were processed with femtosecond laser pulses on a large process window consisting of 32 process conditions to obtain SEM images with various surface morphologies and corresponding reflection spectra. The image prediction model is based on a conditional generative adversarial network, which generates a surface SEM image from the laser fluence and scanning speed values. The reflectance prediction model was developed based on ResNet152 and Long-Short Term Memory network. The average accuracies for the pattern period and ripple width were 98.2 and 94.6 %, respectively, and the L2 norm error for the reflection spectra was less than 4 %. It was demonstrated that the reflection spectra can be accurately predicted using only surface images, which can also be accurately generated from process parameters.

Assembling Biocompatible Polymers on Gold Nanoparticles: Toward a Rational Design of Particle Shape by Molecular Dynamics.

Gold nanoparticles (AuNPs) have received great attention in a number of fields ranging from the energy sector to biomedical applications. As far as the latter is concerned, due to rapid renal clearance and a short lifetime in blood, AuNPs are often encapsulated in a poly(lactic-co-glycolic acid) (PLGA) matrix owing to its biocompatibility and biodegradability. A better understanding of the PLGA polymers on the AuNP surface is crucial to improve and optimize the above encapsulation process. In this study, we combine a number of computational approaches to explore the adsorption mechanisms of PLGA oligomers on a Au crystalline NP and to rationalize the PLGA coating process toward a more efficient design of the NP shape. Atomistic simulations supported by a recently developed unsupervised machine learning scheme show the temporal evolution and behavior of PLGA clusterization by tuning the oligomer concentration in aqueous solutions. Then, a detailed surface coverage analysis coupled with free energy landscape calculations sheds light on the anisotropic nature of PLGA adsorption onto the AuNP. Our results prove that the NP shape and topology may address and privilege specific sites of adsorption, such as the Au {1 1 1} crystal planes in selected NP samples. The modeling-based investigation suggested in this article offers a solid platform to guide the design of coated NPs.

Mitigation of corrosion of zinc with amylopectin: Electrochemical, adsorption, and surface studies

AbstractCarbohydrate polymers are proven to be potential green corrosion inhibitors because of their outstanding structural features and eco‐friendliness. Work undertaken reflects the effectiveness of biopolymer amylopectin (AMP) as an eco‐friendly green inhibitor to mitigate the deterioration of zinc in 0.1 M sulphamic acid (NH2SO3H). Electrochemical studies like potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) were applied for corrosion rate measurement in the absence and presence of AMP. Thermodynamic and kinetic parameters were calculated and described in detail. The results were fitted into a suitable adsorption isotherm model, and an appropriate mechanism was proposed for the corrosion inhibition process. A detailed surface morphology study was done using scanning electron microscopy (SEM), electron‐dispersive X‐ray (EDX), and atomic force microscopy (AFM) techniques. The inhibition efficacy of AMP increased with an increase in its concentration and temperature. Upon the addition of the inhibitor, corrosion potential shifted more towards the positive side, indicating more control of the anodic process. The adsorption of AMP over zinc conformed to the Freundlich adsorption isotherm. For the concentration of 0.1 gL−1, maximum corrosion inhibition efficiency of 74% could be accomplished. Surface studies reaffirmed the adsorption of AMP on the surface of the metal. Thus, AMP turned out to be an effective green inhibitor with economic benefits.

Shading aware DSM generation from high resolution multi-view satellite images

ABSTRACT In many cases, the Digital Surface Models (DSMs) and Digital Elevation Models (DEMs) are obtained with Light Detection and Ranging (LiDAR) or stereo matching. As an active method, LiDAR is very accurate but expensive, thus often limiting its use in small-scale acquisition. Stereo matching is suitable for large-scale acquisition of terrain information as the increase of satellite stereo sensors. However, underperformance of stereo matching easily occurs in textureless areas. Accordingly, this study proposed a Shading Aware DSM GEneration Method (SADGE) with high resolution multi-view satellite images. Considering the complementarity of stereo matching and Shape from Shading (SfS), SADGE combines the advantage of stereo matching and SfS technique. First, an improved Semi-Global Matching (SGM) technique is used to generate an initial surface expressed by a DSM; then, it is refined by optimizing the objective function which modeled the imaging process with the illumination, surface albedo, and normal object surface. Different from the existing shading-based DEM refinement or generation method, no information about the illumination or the viewing angle is needed while concave/convex ambiguity can be avoided as multi-view images are utilized. Experiments with ZiYuan-3 and GaoFen-7 images show that the proposed method can generate higher accuracy DSM (12.5–56.3% improvement) with sound overall shape and temporarily detailed surface compared with a software solution (SURE) for multi-view stereo.

Research on a single-point butt clinching process with various forming forces

With the rapid emergence of lightweight materials, the joining process of various lightweight materials has developed to a popular research spot in the engineering field. In this work, a novel type of butt form based on the mechanical clinching process was proposed, which is a single-point clinching process. This method contributed to simplify the clinching process while increase the joining efficiency and produce higher economic benefits. The forming forces of 25, 30, 35, 40 and 45 kN were exerted to produce the dissimilar single-point butt joints. In addition, main geometrical parameters of the mechanical interlock structure, static mechanical properties, SEM morphology of the fracture surface and failure details of dissimilar joints were analyzed by experimental method. The experimental results indicated that both static strength and energy absorption capacity of the single-point butt joint produced by AA5052 sheets are proportional to the forming force in the range of 25–45 kN. The single-point butt joint produced with 45 kN forming force has the most outstanding performance on static shearing strength (1014.2 N) and energy absorption value (0.825 J). Neck fracture is the main failure mode during the static strength test in this work. Furthermore, microscopic morphology of the fracture surface on AA5052 single-point butt joint indicates that ductile fracture is the mainly failure form, and the large number of dimples facilitate the absorption of the energy during the fracture process. The process proposed in this work is particularly suited to components that cannot meet the length requirements of the lap form and are subject to comparatively small shearing force.

Detailed Avatar Recovery From Single Image.

This paper presents a novel framework to recover detailed avatar from a single image. It is a challenging task due to factors such as variations in human shapes, body poses, texture, and viewpoints. Prior methods typically attempt to recover the human body shape using a parametric-based template that lacks the surface details. As such resulting body shape appears to be without clothing. In this paper, we propose a novel learning-based framework that combines the robustness of the parametric model with the flexibility of free-form 3D deformation. We use the deep neural networks to refine the 3D shape in a Hierarchical Mesh Deformation (HMD) framework, utilizing the constraints from body joints, silhouettes, and per-pixel shading information. Our method can restore detailed human body shapes with complete textures beyond skinned models. Experiments demonstrate that our method has outperformed previous state-of-the-art approaches, achieving better accuracy in terms of both 2D IoU number and 3D metric distance.

MRS-Tex: A Magnetically Responsive Soft Tactile Device for Texture Display

Tactile devices provide an intuitive way for texture display, which allows users to perceive the detailed surface properties of virtual or remote objects. For existing tactile devices that create actual topographical transformations, it remains challenging to render surface textures with high spatial resolution due to the limitation of the size of actuators. To address this challenge, a magnetically responsive soft actuator with a diameter of 1 mm is proposed. Integrating the high-density soft actuator array and a soft membrane bracket, we develop a magnetically responsive soft tactile device (named MRS-Tex) for texture display. When a magnetic field is applied, the magnetic units will sink to form pits, and the soft membrane bracket resists the finger pressure so that users can perceive the rendered surface texture. Thanks to the proposed sunken solution, MRS-Tex is capable of rendering surface textures with millimeter-level resolution (1.5 mm) while providing a sufficient upward holding force. Moreover, we conduct quantitative experiments and two user studies to evaluate the performance of MRS-Tex. Experimental results show that MRS-Tex can generate pits with a depth of more than 0.20 mm, which is sufficient for rendering perceivable surface textures. The average discrimination accuracy of user study can reach up to 82% for both six basic texture patterns and four complex texture patterns.