Object Surface Research Articles

Visibly transparent multifunctional camouflage coating with efficient thermal management.

Camouflage technology has attracted growing interest in many thermal applications. In particular, high-temperature infrared (IR) camouflage is crucial to the effective concealment of high-temperature objects but remains a challenging issue, as the thermal radiation of an object is proportional to the fourth power of temperature. Here, we proposed a coating to demonstrate high-temperature IR camouflage with efficient thermal management. This coating is a combination of hyperbolic metamaterial (HMM), gradient epsilon near zero (G-ENZ) material, and polymer. HMM makes the coating transparent in the visible range (300-700 nm) and highly reflective in the IR region, so it can serve as a thermal camouflage in the IR. G-ENZ and polymer support BE mode (at higher angles ∼50° to 90° in the 11-14 µm atmospheric window) and vibrational absorption band (in 5-8 µm non-atmospheric for all angles), respectively. So it is possible to achieve efficient thermal management through radiative cooling. We calculate the temperature of the object's surface, considering the emissivity characteristics of the coating for different heating temperatures. A combination of silica aerogel and coating can significantly reduce the surface temperature from 2000 K to 750 K. The proposed coating can also be used in the visible transparent radiative cooling due to high transmission in the visible, high reflection in the near-IR (NIR), and highly directional emissivity in the atmospheric window at higher angles, and can therefore potentially be used as a smart window in buildings and vehicles. Finally, we discuss one more potential future application of such a multifunctional coating in water condensation and purification.

A triboelectric tactile sensor with flower-shaped holes for texture recognition

Touch is one of the important ways to perceive the surrounding environment. The surface texture is an essential character of an object. Here, we propose a dual-layer shielding triboelectric tactile sensor with patterned flower-shaped holes. The object surface to be measured is able to rub against the tribo-layer through the flower-shaped holes to produce a signal output. The patterned design of the tactile sensor is evolved from the contact state of the fingertips during human finger touch. In addition, two shielding layers were designed. The inner-shielding layer is used to shield the influence of the human body potential on the output signal, in order to achieve more accurate identification. The outer-shielding layer enables the flower-shaped holes to play their structural role. The proposed tactile sensor has the advantage of a single channel, resulting in a smaller amount of data collection and processing than the multi-channel scheme. With a designed convolutional neural network model, the recognition accuracy reaches 96.03% when recognizing 7 objects with designed different surface textures and 92.58% when recognizing 5 kinds of fruits and vegetables. The tactile sensing module can be easily integrated into intelligent haptic prosthesis and play an important role in future human-machine interfaces.

Two-step diffraction method for an optical 360° cylindrical holographic display.

We present a two-step diffraction method for an optical 360∘ cylindrical holographic display with a planar spatial light modulator (SLM) and a 45∘ conical mirror. The first step involves layered diffraction of the cylindrical object surface to obtain the complex amplitude distribution on the conical mirror, and the second step is the coordinate transformation, followed by plane-to-plane diffraction to finally obtain the hologram. Numerical simulations and optical experiments show that our proposed method offers improved accuracy in the propagation process compared with the previous method; furthermore, it enables better quality of reconstruction, particularly at large radius of object surface. We believe it is a solid step toward practicality for a cylindrical holographic display.

Advances in Photocatalytic Disinfection: Performances and Mechanisms

Photocatalytic technology is a sustainable, efficient, and eco‐friendly advanced oxidation process for addressing the hazards of microorganisms (bacteria and viruses). In this article, the latest results in the studies on the use of semiconductor photocatalysts to remove microorganisms and their related genes (DNA and RNA) from the environment, including operating conditions and removal efficiency, are summarized. The photocatalytic‐disinfection mechanism is described in detail, related to solar (especially ultraviolet light) disinfection, physical damage by sharp edges of photocatalysts, and various reactive oxygen species generated during photocatalytic processes. Also, the difficulties and challenges of photocatalytic disinfection in practical applications are discussed. With the further development of photocatalysis technology, sunlight‐driven and even indoor‐light‐driven photocatalysts will have a more promising application in environmental disinfection involving water, air, and object surfaces.

Segmentation quality assessment by automated detection of erroneous surface regions in medical images

Despite the advancement in deep learning-based semantic segmentation methods, which have achieved accuracy levels of field experts in many computer vision applications, the same general approaches may frequently fail in 3D medical image segmentation due to complex tissue structures, noisy acquisition, disease-related pathologies, as well as the lack of sufficiently large datasets with associated annotations. For expeditious diagnosis and quantitative image analysis in large-scale clinical trials, there is a compelling need to predict segmentation quality without ground truth. In this paper, we propose a deep learning framework to locate erroneous regions on the boundary surfaces of segmented objects for quality control and assessment of segmentation. A Convolutional Neural Network (CNN) is explored to learn the boundary related image features of multi-objects that can be used to identify location-specific inaccurate segmentation. The predicted error locations can facilitate efficient user interaction for interactive image segmentation (IIS). We evaluated the proposed method on two data sets: Osteoarthritis Initiative (OAI) 3D knee MRI and 3D calf muscle MRI. The average sensitivity scores of 0.95 and 0.92, and the average positive predictive values of 0.78 and 0.91 were achieved, respectively, for erroneous surface region detection of knee cartilage segmentation and calf muscle segmentation. Our experiment demonstrated promising performance of the proposed method for segmentation quality assessment by automated detection of erroneous surface regions in medical images.

Modeling Processes of Emergence and Growth of Fractal Structures and Chamber Defects of Thermal Power Units. Part 2

The paper describes further development of model studies with the purpose to draw analogies of the occurrence of possible inhomogeneities and defects of the fractal type on the surface of various objects under the action of laser radiation for different conditions and schemes of a laser simulation experiment in comparison with real processes in the chambers of thermal machines due to the contacts of the working substances with their surface. The subject of this consideration is related to the fact that in laser schemes one can relatively easily and in a controlled manner to study their topology in various modifications (in the range of 0D–3D structures formed on surfaces of various geometric shapes of the fractal type). This provides great opportunities for studying various frequently occurring undesirable random defects and inhomogeneities of complex configuration with the development of unexpected processes in the dynamic modes of operation of various types of power units in their actual operation. This is determined by geometric analysis within the framework of the correspondding non-linear models with different non-linear fractal images. In this aspect, we have used two models to consider the development of emerging fractal fractured structures: first, diffusion propagation/growth of cracks of different geometry with a set of local segments and fragments in different directions; secondly, with diffusely limited aggregation of their distribution (Diffusion-Limited Aggregation – DLA) using the formalism of cellular automata in percolation approximation for different algorithms for the formation of fractal structures. We present only the final results of calculations without details of their procedure, which is sufficient for a visual and qualitative determination of the process of growth of fracturing and defects. In this case, the final goal of consideration is to study the emergence of possible and controllable local areas / collectors, starting from surface structures, and their association with real objects on the surface of chambers with a working substance in power systems. The possible practical significance of such modeling and analysis is discussed to forecast their working conditions.

Digital Holographic Interferometry for Wholefield NDT Applications

Holographic interferometry is a non-contact whole field optical technique used as a powerful NDT tool. This technique is highly sensitive and maps the object surface deformation as holographic fringe pattern. Conventional holography technique has practical difficulties in recording and reconstructing holograms. With the development in imaging sensor technology and fast algorithms in image processing, digital holography has been established. Digital holography uses high-resolution digital camera for recording holograms and does reconstruction of holograms numerically using a computer. This has enhanced the scope and application of holography for NDT many fold. In this paper application of digital holography to non-destructive testing is presented. The basic principle of digital holography and digital holographic interferometry in obtaining double exposure hologram for NDT is described. The software developed in house for numerical reconstruction of holograms is also explained. The advantages of digital holography over conventional holography in NDT applications are highlighted. Extensive experiments were carried out to prove the detectability of defects in both metallic and non-metallic materials and the results are presented. It is shown that digital holography is able to identify defects in a wide range of materials with great ease because of its high sensitivity and whole field nature.

Cultural relic reconstruction device based on ORB-SLAM

ORB-SLAM, an advanced visual SLAM technology, has excellent positioning and mapping capabilities [1]. In the reconstruction of cultural relics, ORB-SLAM technology can achieve autonomous perception and modeling of the surrounding environment of cultural relics by fusing and analyzing the images of monocular depth cameras, thereby reconstructing the 3D model of cultural relics, providing new possibilities for the protection and inheritance of cultural relics. Point cloud images are a digital technology used for 3D modeling, which can save point data on object surfaces and their relationships as 3D point clouds [2]. In terms of cultural relic reconstruction, point cloud images can restore and reconstruct the shape, size, texture, and other features of cultural relics by processing the collected point data on the surface of cultural relics into a 3D model. The purpose of this device is to reconstruct cultural relics by generating point cloud images based on ORB-SLAM technology. Combined with the designed handheld pan tilt device, it can achieve multi-angle point cloud mapping of cultural relics scenes in complex terrain. This paper will introduce the handheld gimbal design of the device, the realization of point cloud mapping based on the ORB-SLAM3 algorithm [3], and the application of point cloud scenes. Through the research in this article, it is expected to provide a new and efficient method for cultural relic reconstruction in the field of cultural relic protection and make contributions to the protection and inheritance of cultural heritage.

Combining radar and ultrasound imaging for surface echo compensation and augmented visibility of interior structures in NDT applications

Millimeter-wave radar imaging is a promising technique in non-destructive testing. When a small material defect is located closely to the test object’s surface, the strong reflection caused by the air-material interface can overlap with the defect’s weak reflection and mask it. If the image resolution is not sufficient, the defect cannot be resolved and will not be recognizable in the reconstruction image. To solve this problem, surface echo compensation techniques have been invented. However, these techniques are usually restricted to planar surfaces, which for most applications is not the case. This article presents a technique for surface echo compensation of arbitrarily shaped objects. We propose to combine radar and air-coupled ultrasound. Since aircoupled ultrasound is not able to penetrate solids, an air-coupled ultrasound imaging system is only able to detect the surface of a solid object. The idea of our proposed concept is to employ the ultrasound signal to compensate for the surface echo in the radar signal. The proposed method is based on the idea of using signals of equal wavelengths for both wave types and an amplitude calibration. Then, the resulting signals for radar and ultrasound are formally equal, which makes it possible to directly combine them numerically. That way, a modified radar image can be obtained which only contains the reflections from the inside and highlights interior defects.

Visual selection of multi-digit contact surfaces for objects of varying mass

Visual selection of multi-digit contact surfaces for objects of varying mass

Response Optimization of Machining Parameters using MCDA-Vikor Method for Acrylic Glass with AHAJM

Abstract: Abrasive Hot Air Jet Machining (AHJM) is becoming one of the most prominent machining techniques forPolymethyl Methacrylate (PMMA) and other brittle materials. In this attempt has been made to combine abrasive and hot air to form an abrasive hot air jet. Abrasive hot air jet machining can be connected to different tasks, for example, boring, surface scratching, scoring and small scale completing on the glass and its composites. The impact of air temperature onthe material expulsion rate connected to the procedure of glass carving and scoring is talked about in this article. The unpleasantness of the machined surface is additionally investigated. It is discovered that the material removal rate (MRR) increments as the temperature of transporter media (air) is expanded. In the present work to be attempt to investigate machining characteristics of PMMA material on hot air abrasive jet machining. In hot air abrasive jet machining(HAJM) abrasive particles stay on abrasive particle stay molten by compacted air in a closed chamber and are intensive over the objective surface over a nozzle the stream of particles coming out of the nozzle through very high velocity’s (175-300m/s) impacts the objective surface and eliminates the material by destruction. The investigation has to be carried on to study the effect of process parameters as material removal rate(MRR) as surface roughness(SR) with different input parameters like Air Pressure, , Size Of Abrasives , Stand-Off Distance ,Temperature Of Carrier Gas. In this experimental process Tungstencarbide coated nozzles were to be used flow of silicon carbide(sic) particles will be used.The Poly(methyl methacrylate) (PMMA), furthermore saw as acrylic glass, acrylic material, or plexiglass as suitably as by using the change names Plexiglas, Crylux, Lucite, Acrylate. PMMA it is an unquestionable thermoplastic .the creation formula of PMMA is (C5O2H8)n it has incredible properties to, for instance, lightweight, 92% Transparent observable light effect inside 3mm of thick material, extraordinary solidarity to consider another polystyrene. it's for the most part important in these zones, for instance, Because of its direct properties, lightweight and preferable quality took a gander at over glass, It was broadly usedto make aircraft windshields, shades and weapon turrets. After this couple of different business applications were made for PMMA, for instance, glass material, façade arrangement, publicizing, vehicle headlamps, etc.,

NeRO: Neural Geometry and BRDF Reconstruction of Reflective Objects from Multiview Images

We present a neural rendering-based method called NeRO for reconstructing the geometry and the BRDF of reflective objects from multiview images captured in an unknown environment. Multiview reconstruction of reflective objects is extremely challenging because specular reflections are view-dependent and thus violate the multiview consistency, which is the cornerstone for most multiview reconstruction methods. Recent neural rendering techniques can model the interaction between environment lights and the object surfaces to fit the view-dependent reflections, thus making it possible to reconstruct reflective objects from multiview images. However, accurately modeling environment lights in the neural rendering is intractable, especially when the geometry is unknown. Most existing neural rendering methods, which can model environment lights, only consider direct lights and rely on object masks to reconstruct objects with weak specular reflections. Therefore, these methods fail to reconstruct reflective objects, especially when the object mask is not available and the object is illuminated by indirect lights. We propose a two-step approach to tackle this problem. First, by applying the split-sum approximation and the integrated directional encoding to approximate the shading effects of both direct and indirect lights, we are able to accurately reconstruct the geometry of reflective objects without any object masks. Then, with the object geometry fixed, we use more accurate sampling to recover the environment lights and the BRDF of the object. Extensive experiments demonstrate that our method is capable of accurately reconstructing the geometry and the BRDF of reflective objects from only posed RGB images without knowing the environment lights and the object masks. Codes and datasets are available at https://github.com/liuyuan-pal/NeRO.

Quasi-pointwise two-step phase-shifting profilometry with the fringe parameters estimated statistically.

Fringe projection profilometry is a popularly used three-dimensional measurement technique in which phase-measuring algorithms based on two-step phase shifting are usually used because of their best tradeoff between measurement resolution and speed. Most two-step phase-shifting algorithms involve neighboring or other spatial operations, thus having degraded accuracies at edges and discontinuities of the measured object surface. Pointwise two-step algorithms enable overcoming this issue. With them, however, the offsets of the dynamic ranges of the projector and camera are usually improperly overlooked or inaccurately estimated, thus inducing errors in their measurement results. For solving this problem, this paper suggests a quasi-pointwise two-step phase-shifting algorithm for fringe projection profilometry. This algorithm models the captured fringe patterns practically by taking the offsets of the dynamic ranges of the projector and camera into account, and estimates the fringe parameters from the statistics of fringe intensities. As a result, we can calculate fringe phases in a pointwise way from two fringe patterns having a phase difference of π/2 radians. The simulation and experimental results demonstrate that the proposed method has a relatively low level of errors in measuring object surfaces having isolated regions and discontinuities.

Study of the roughness effect on the normal spectral emissivity of GH3044

The normal spectral emissivity is a significant parameter characterizing the radiative capacity of the object's surface. However, the normal spectral emissivity of superalloys varies with the rough state of the surface, causing unacceptable errors in radiation thermometry and heat transfer calculation for aero-engines and gas turbines. A computational method for estimating the effect of roughness on the normal spectral emissivity of superalloys was established based on constructing randomly rough surfaces. Through this method, the effect of roughness on four emissivity models commonly used in multispectral radiometric thermometry (MRT) was computationally evaluated, and the relationship between roughness and spectral emissivity was quantitatively analyzed. In addition, the normal spectral emissivity of GH3044 superalloy with different rough surfaces at 300 K and high temperatures was experimentally measured and compared with the result calculated by this computational method. Their maximum relative error was close to ± 5 % for the rough surface without emissivity oscillation. This study promotes understanding the mechanism of normal spectral emissivity varying with roughness.

Acoustodynamic Covalent Materials Engineering for the Remote Control of Physical Properties Inside Materials.

Advances in vat-photopolymerization (VP) three-dimensional printing (3DP) technology enable the production of highly precise 3D objects. However, it has been a major challenge to create dynamic functionalities and to manipulate the physical properties of the inherently insoluble and infusible crosslinked material generated from VP-3DP without reproduction. Here, we report the fabrication of light- and high-intensity focused ultrasound (HIFU)-responsive crosslinked polymeric materials linked with hexaarylbiimidazole (HABI) in polymer chains based on VP-3DP. Although the photochemistry of HABI produces triphenylimidazolyl radicals (TPIRs) during the process of VP-3DP, the orthogonality of the photochemistry of HABI and photopolymerization enables the introduction of reversible crosslinks derived from HABIs in the resulting 3D printed objects. While photostimulation cleaves a covalent bond between two imidazoles in HABI to generate TPIRs only near the surface of the 3D printed objects, HIFU triggers cleavage in the interior of materials. In addition, HIFU travels beyond an obstacle to induce a response of HABI-embedded crosslinked polymers, which cannot be attainable with photostimulation. The present system would be beneficial for tuning the physical properties and recycling of various polymeric materials, but it will also open the door for pinpoint modification, healing, and reshaping of materials when coupled to various dynamic covalent materials. This article is protected by copyright. All rights reserved.

Computer-Aided Design on Image Detection: A Chronology Review

In order to conduct research and diagnose diseases, image processing is essential. Medical professionals frequently segment images for pre- and post-surgery decisions, which are necessary for treatment planning. In the medical research field, segmentation is the core subject of several studies. Computer-aided detection (CAD) is utilised to achieve the highest level of classification accuracy and may be used to identify tissues growing abnormally. For the purpose of finding abnormalities, magnetic resonance imaging (MRI) is an effective approach, but it takes time and requires a fair amount of human resources. This approach, however, was problematic for slicing data related to the interior surfaces of cavity structures, for instance, the human skull. As a result, a ray casting algorithm was used to create a software programme. The most significant problem with segmentation techniques for x-ray images is seed point selection. An object's surface structure is described by a three-dimensional (3D) surface structure graph (SSG) that was created during segmentation. Ultrasound image detection is critical today. The model can be further modified using this CAD software so that it can be reproduced on a rapid prototyping device in the STL file format. The suggested deep learning method is exceptionally effective in accurately detecting faults in each layer, according to experimental data.

Optimization of trajectory processing algorithms to print 3D circuit boards using piezo ink jet and 6-axis robots

Direct printing of conductive inks at the surface of generic 3D objects using 6 axis robots is attracting an ever-increasing interest, however the high precision positioning and the generation of smooth printing trajectories still represent a bottleneck for the manufacturing of 3D electronic circuits. This work presents a new approach for the rapid prototyping of 3D electronics onto generic objects using a 6 axis robot equipped with a piezo jetting printhead and a high speed laser profiler and a six steps protocol composed by the: i) 3D scan of the substrate and mesh smoothing, ii) 2D circuit projection on the planarized mesh and generation of the 3D trajectory, iii) normals alignment of points lying in the 3D trajectory, iv) retrieve of the effective toolhead TCP translation speed along the 3D trajectory with a blank run, v) synchronization of the ink jetting frequency with the effective toolhead speed, vi) generation of the robot code and print.The effect of mesh and normals smoothing and of circuit design on the effective toolhead translation speed was systematically investigated in order to minimize speed fluctuations/heterogeneous ink deposition during printing, the computational load and shape deviation from the pristine 3D substrate.Conductive tracks printed on an ABS dome displayed geometry and line resistance in line with those predicted by a semi-empirical model using the robot nominal speed and silver ink conductivity, thus showing that the robot operated under stable and well controlled conditions during the printing process.The developed process displayed an average duty cycle of ca. 30 min from the 3D scan to the printing of the 3D circuit, thus showing that it could be suitable for the rapid prototyping/benchmarking of 3D electronics on generic objects.

Phase compensation algorithm based on image segmentation in dual-wavelength holographic microscopy.

In order to solve the problem of phase compensation errors in the traditional 2π phase compensation method caused by a rough surface and complex structure of objects in dual-wavelength digital holographic microscopy, a phase compensation algorithm based on image segmentation was proposed. First, the phase less than zero in the phase obtained by an equivalent wavelength is compensated for by adding 2π initially. Then the phase after the initial compensation is binarized, and the small connected areas in the binarized graph are removed, so as to obtain a new binarized graph. Finally, according to the two binarized graphs, the phase of the object after the initial 2π phase compensation is recompensated for in different regions, so as to obtain the continuous phase distribution of the object. Based on the dual-wavelength digital holographic microscopy experimental system with an adjustable equivalent wavelength, the proposed algorithm is used to perform three-dimensional imaging of the channel of the microfluidic chip. The experimental results show that the proposed method can effectively obtain the continuous real phase of the object when the structure of the object is known, so as to obtain a more accurate and reliable three-dimensional topography of the object. The above results provide a new idea for the high-quality three-dimensional imaging of the microfluidic system.

Broadband Photodetectors and Imagers in Stretchable Electronics Packaging.

The integration of flexible electronics with optics can help realize a powerful tool that facilitates the creation of a smart society wherein internal evaluations can be easily performed nondestructively from the surface of various objects that is used or encountered in daily lives. Here, organic-material-based stretchable optical sensors and imagers that possess both bending capability and rubber-like elasticity are reviewed. The latest trends in nondestructive evaluation equipment that enable simple on-site evaluations of health conditions and abnormalities are discussed without subjecting the targeted living bodies and various objects to mechanical stress. Real-time performance under real-life conditions is becoming increasingly important for creating smart societies interwoven with optical technologies. In particular, the terahertz (THz)-wave region offers a substance- and state-specific fingerprint spectrum that enables instantaneous analyses. However, to make THz sensors accessible, the following issues must be addressed: broadband and high-sensitivity at room temperature, stretchability to follow the surface movements of targets, and digital transformation compatibility. The materials, electronics packaging, and remote imaging systems used to overcome these issues are discussed in detail. Ultimately, stretchable optical sensors and imagers with highly sensitive and broadband THz sensors can facilitate the multifaceted on-site evaluation of solids, liquids, and gases.

Color and gloss constancy under diverse lighting environments.

When we look at an object, we simultaneously see how glossy or matte it is, how light or dark, and what color. Yet, at each point on the object's surface, both diffuse and specular reflections are mixed in different proportions, resulting in substantial spatial chromatic and luminance variations. To further complicate matters, this pattern changes radically when the object is viewed under different lighting conditions. The purpose of this study was to simultaneously measure our ability to judge color and gloss using an image set capturing diverse object and illuminant properties. Participants adjusted the hue, lightness, chroma, and specular reflectance of a reference object so that it appeared to be made of the same material as a test object. Critically, the two objects were presented under different lighting environments. We found that hue matches were highly accurate, except for under a chromatically atypical illuminant. Chroma and lightness constancy were generally poor, but these failures correlated well with simple image statistics. Gloss constancy was particularly poor, and these failures were only partially explained by reflection contrast. Importantly, across all measures, participants were highly consistent with one another in their deviations from constancy. Although color and gloss constancy hold well in simple conditions, the variety of lighting and shape in the real world presents significant challenges to our visual system's ability to judge intrinsic material properties.