MAXIMUM likelihood statistics, LEAST squares, LETTERS, and RESPONSE surfaces (Statistics)
An optimal, in the least squares sense, method is proposed to estimate surface normals in both stereo and multi-view cases. The proposed algorithm exploits exclusively photometric information via affine correspondences and estimates the normal for each correspondence independently. The normal is obtained as a root of a quartic polynomial. Therefore, the processing time is negligible. Eliminating the outliers, we propose a robust extension of the algorithm that combines maximum likelihood estimation and iteratively re-weighted least squares. The method has been validated on both synthetic and publicly available real-world datasets. It is superior to the state of the art in terms of accuracy and processing time. Besides, we demonstrate two possible applications: 1) using our algorithm as the seed-point generation step of patch-based multi-view stereo method, the obtained reconstruction is more accurate, and the error of the 3D points is reduced by 30% on average and 2) multi-plane fitting becomes more accurate applied to the resulting oriented point cloud. [ABSTRACT FROM AUTHOR]
PHOTOMETRIC stereo, REFLECTANCE, WAGES, and STEREO vision (Computer science)
The surface normal estimation from photometric stereo becomes less reliable when the surface reflectance deviates from the Lambertian assumption. The non-Lambertian effect can be explicitly addressed by physics modeling to the reflectance function, at the cost of introducing highly nonlinear optimization. This paper proposes a numerical compensation scheme that attempts to minimize the angular error to address the non-Lambertian photometric stereo problem. Due to the multifaceted influence in the modeling of non-Lambertian reflectance in photometric stereo, directly minimizing the angular errors of surface normal is a highly complex problem. We introduce an alternating strategy, in which the estimated reflectance can be temporarily regarded as a known variable, to simplify the formulation of angular error. To reduce the impact of inaccurately estimated reflectance in this simplification, we propose a numerical compensation scheme whose compensation weight is formulated to reflect the reliability of estimated reflectance. Finally, the solution for the proposed numerical compensation scheme is efficiently computed by using cosine difference to approximate the angular difference. The experimental results show that our method can significantly improve the performance of the state-of-the-art methods on both synthetic data and real data with small additive costs. Moreover, our method initialized by results from the baseline method (least-square-based) achieves the state-of-the-art performance on both synthetic data and real data with significantly smaller overall computation, i.e., about eight times faster compared with the state-of-the-art methods. [ABSTRACT FROM AUTHOR]
SECONDARY electron emission, SURFACE preparation, SURFACE coatings, MICROWAVES, and AVALANCHES
The Secondary Electron Emission (SEE) from materials used in high-power RF devices in space is the main trigger and sustaining mechanism of the resonant avalanche electron discharge known as the multipactor effect. Multipactor effect is one of the key issues to limit the application of high-power microwave components in space. Starting from the mechanism of multipactor, the basic physical mechanism of two types of multipactors (single-surface and two-surface)is briefly introduced, and then the current mainstream of multipactor suppression methods are summarized and the limitations of their respective applications in space high-power microwave components are given. Finally, focusing on the special problem of multipactor suppression in aerospace high-power microwave components, the research work on surface treatment to inhibit multipactor in the past five years is reviewed and the tendencies of multipactor suppression technology are predicted. [ABSTRACT FROM AUTHOR]
Depth and surface normal estimation are crucial components in understanding 3D scene geometry from calibrated stereo images. In this paper, we propose visibility and disparity magnitude constraints for slanted patches in the scene. These constraints can be used to associate geometrically feasible planes with each point in the disparity space. The new constraints are validated in the PatchMatch Stereo framework. We use these new constraints not only for initialization, but also in the local plane refinement step of this iterative algorithm. The proposed constraints increase the probability of estimating correct plane parameters, and lead to an improved 3D reconstruction of the scene. Furthermore, the proposed constrained initialization reduces the number of iterations before convergence to the optimal plane parameters. In addition, as most stereo image pairs are not perfectly rectified, we modify the view propagation process by assigning the plane parameters to the neighbors of the candidate pixel. To update the plane parameters in the plane refinement step, we use a gradient free non-linear optimizer. The benefits of the new initialization, propagation, and refinement schemes are demonstrated. [ABSTRACT FROM AUTHOR]
graphene oxide, nitrogen, surface treatment, epoxy composites, and mechanical properties
The effects of ammonia-treated graphene oxide (GO) on composites based on epoxy resin were investigated. Ammonia solutions of different concentrations (14–28%) were used to modify GO. Nitrogen functional groups were introduced on the GO surfaces without significant structural changes. The ammonia-treated GO-based epoxy composites exhibited interesting changes in their mechanical properties related to the presence of nitrogen functional groups, particularly amine (C-NH2) groups on the GO surfaces. The highest tensile and impact strength values were 42.1 MPa and 12.3 J/m, respectively, which were observed in an epoxy composite prepared with GO treated with a 28% ammonia solution. This improved tensile strength was 2.2 and 1.3 times higher than those of the neat epoxy and the non-treated GO-based epoxy composite, respectively. The amine groups on the GO ensure its participation in the cross-linking reaction of the epoxy resin under amine curing agent condition and enhance its interfacial bonding with the epoxy resin.
ULTRAFILTRATION, CONGO red (Dye), AMARANTH products, SURFACE preparation, SEPARATION (Technology), and AQUEOUS solutions
Although ultrafiltration membranes have been used for the separation of macromolecules and colloids from solutions, this process has a limited application in the removal of dyes present in coloured discharges of textile industry, as these typically have much lower molecular weight than the molecular cut-off of the membranes (MWCO). In the present work, we have evaluated the behaviour of a polysulfone ultrafiltration membrane in the removal of different dyes from aqueous solutions (Congo red, methyl green and amaranth). Different variables (tangential flow rate, concentration of dye and pH of the feed) were studied to determine their influence on the separation processes (permeate flux and rejection coefficient). The results show that Congo red is easily removed with a GR60PP membrane (MWCO = 25 kDa), whereas methyl green and amaranth show rejection coefficient values of approximately 25.78% and 13.85%, respectively, at neutral pH. Also, an interesting effect is observed for the rejection coefficient for methyl green at different pH values. In addition, several treatments were performed to the membrane so as to modify its surface, trying to improve the values obtained for permeate flux and rejection rate. [ABSTRACT FROM AUTHOR]
LIGHT sources, IMAGE processing, COMPUTER vision, PHOTOMETRY, and IMAGE segmentation
Light source position (LSP) estimation is a difficult yet an important problem in computer vision. A common approach for estimating the LSP assumes Lambert’s law. However, in real-world scenes, Lambert’s law does not hold for all different types of surfaces. Instead of assuming all that surfaces follow Lambert’s law, our approach classifies image surface segments based on their photometric and geometric surface attributes (i.e. glossy, matte, curved, and so on) and assigns weights to image surface segments based on their suitability for LSP estimation. In addition, we propose the use of the estimated camera pose to globally constrain LSP for RGB-D video sequences. Experiments on Boom and a newly collected RGB-D video data sets show that the state-of-the-art methods are outperformed by the proposed method. The results demonstrate that weighting image surface segments based on their attributes outperform the state-of-the-art methods in which the image surface segments are considered to equally contribute. In particular, by using the proposed surface weighting, the angular error for LSP estimation is reduced from 12.6° to 8.2° and 24.6° to 4.8° for Boom and RGB-D video data sets, respectively. Moreover, using the camera pose to globally constrain LSP provides higher accuracy (4.8°) compared with using single frames (8.5°). [ABSTRACT FROM PUBLISHER]
AMORPHOUS alloys, MICROSTRUCTURE, MECHANICAL behavior of materials, REACTION mechanisms (Chemistry), OXIDATION kinetics, and SURFACE chemistry
Owing to their unique short- or medium-range ordered microstructures and excellent mechanical, physical, and chemical properties, amorphous alloys have attracted significant interest in recent years. For the application of amorphous alloys, clarifying their oxidation processes and mechanisms is necessary since many of the surface-related properties of amorphous alloys largely depend on the surface oxide layer. The aim of this paper is to review the recent research on the thermal oxidation behaviors of amorphous alloys under pure oxygen or air condition. The contents are divided into three categories according to the number of components the research considers, i.e., the oxidation of binary, ternary, and multi-component (>3) amorphous alloys. Each section discusses the thermal stability of the amorphous matrix, oxidation kinetics, and the oxide layer and amorphous substrate, which are strongly affected by internal factors (i.e., alloy elements and microstructure) and external factors (i.e., oxidation temperature, duration, and oxygen partial pressure, etc.). The general features of the oxidation of amorphous alloys – from simple binary to complex multi-component amorphous alloys – will be summarized. This overview of the current scientific understanding on the fundamentals of these materials may provide guidelines for the development of strongly corrosion-resistant amorphous alloys. [ABSTRACT FROM AUTHOR]
The surface of 304 stainless steels was first disposed by polishing, etching and annealing to achieve micro-nano structures, and then the PA6/stainless steel samples were fabricated by a hot-pressing molding method without using any adhesives. The mechanical characterization results indicated that the joint strength of the resulting samples was only 3.31 MPa after polishing. However, the joint strength of PA6/stainless steel samples reached 17.48 MPa after successively polishing, etching and annealing. There is a transition in failure mode observed from adhesive to cohesive. The surface morphologies of the samples were investigated by scanning electron microscopy and atomic force microscopy, and some micro-nano holes were observed on the surface of stainless steel after etching. It was deduced that the plastic melt could permeate into the micro and/or nano holes on the surface of stainless steel to generate an anchoring effect during the hot-pressing molding process. Fourier-transmission infrared spectroscopic result indicated that PA6 was chemically bonded with the oxides on the annealed metal surface. Such anchoring and chemical bonding effects could improve the mechanical properties of PA6/stainless steel samples. [ABSTRACT FROM AUTHOR]
carbon fibers, thermosetting, surface treatment, composites, and mechanical properties
Carbon fibers (CFs) have a unique combination of properties which allow them to be widely used as reinforcing materials in advanced polymer composites. The mechanical properties of CF-reinforced polymer composites are governed mainly by the quality of interfacial adhesion between the CFs and the polymer matrix. Surface treatments of CFs are generally carried out to introduce chemical functional groups on the fiber surfaces, which provide the ability to control the surface characteristics of CFs. In this study, we review recent experimental studies concerning various surface treatment methods for CFs. In addition, direct examples of the preparation and properties of CF-reinforced thermosetting composites are discussed.
SINGLE crystals, ORGANIC thin films, SURFACE coatings, ORGANIC semiconductors, and SURFACE preparation
Abstract: Meniscus‐guided solution‐coating techniques offer a great potential for the realization of high‐performance, single‐crystalline films of organic semiconductors over large areas. Such techniques rely on the creation of a shallow meniscus and a subsequent one‐directional coating. To achieve shallow meniscus fronts, the wetting behavior of the solvents on the substrate is crucial. Literature typically simply employs high surface energy substrates without investigating the exact impact of the surface treatment on film morphology and electrical characteristics. In this work, the zone‐casting of (2,7‐dioctylbenzothieno[3,2‐b]benzothiophene) is systematically studied on various surface treatments with widely varying surface energies. A fundamental observation is that, as long as the solution wets the substrate with a low contact angle, the morphology of the coated thin films is independent from the surface treatment. Through a systematic characterization of the wetting envelope of the treated substrate, a predictive rule for the wetting behavior is defined that is more accurate than the quantification of substrate surface energy alone. Furthermore, thin films formed on different surfaces show similar mobilities, but can nevertheless display largely varying threshold voltages. Hence, such films are ideal to study the influence of different surface treatments on the electrical characteristics without interference from morphological effects. [ABSTRACT FROM AUTHOR]
NICKEL sulfide, SULFURIC acid, OXALIC acid, PHOSPHORIC acid, and SURFACE states
Abstract: The influences of acids on the surface of nickel foam and its effect on the growth of nickel sulfide are studied. Treated by sulfuric acid, oxalic acid, and phosphoric acid, three Ni foams are fabricated with different surface states containing different surface roughness and different surface layers with nickel salts. By controlling the reaction conditions, three Ni3S2 morphological structures with nanosheets, clustered nanosheets, and nanoparticles are designed on these preprocessed Ni foams. The applications of these Ni3S2/Ni electrodes for sodium ion batteries are examined in detail. The findings provide a new idea for the control of the solid–liquid reaction interface, which highly affect the morphologies of Ni3S2. [ABSTRACT FROM AUTHOR]
Vallero, Alessandro, Tzouvadaki, Ioulia, Puppo, Francesca, De Micheli, Giovanni, Carrara, Sandro, Doucey, Marie-Agnes, and Delaloye, Jean-Francois
IEEE Transactions on Circuits & Systems. Part I: Regular Papers. Dec2016, Vol. 63 Issue 12, p2120-2127. 8p.
BIOSENSORS, MACHINE design, MICROFLUIDIC devices, and DATA acquisition systems
The integration of nanoscale sensors with microfluidic platforms is a powerful tool for the design of robust biosensing devices that present high reliability and the advantage of a quick data acquisition. In addition, microfluidic based lab-on-a-chip sensors require minute amounts of clinical samples and cancer biosensing products. However, the integration of nanostructures in such more complex configurations may significantly complicate the electrical readout process. The aim of the present work is to develop improved devices for cancer prognosis based on nanofabricated Memristive Biosensors integrated for the first time with a microfluidic structure. The effective readout of the Memristive Biosensors electrical response is enabled through a series of specially designed metal line extensions realized accordingly in order to fully retain the sensing output signal. [ABSTRACT FROM PUBLISHER]
Zardetto, Valerio, di Giacomo, Francesco, Lifka, Herbert, Verheijen, Marcel A., Weijtens, Christ H. L., Black, Lachlan E., Veenstra, Sjoerd, Kessels, Wilhelmus M. M., Andriessen, Ronn, and Creatore, Mariadriana
TITANIUM dioxide, FLUORINATION, ATOMIC layer deposition, ELECTRON transport, PEROVSKITE, SOLAR cells, and ELECTRIC power conversion
Abstract: Perovskite solar cells (PSCs) are emerging among the photovoltaic (PV) technologies due to their high power conversion efficiency (PCE) in combination with potentially low cost manufacturing processing. In this contribution, the fabrication of efficient planar n‐i‐p PSCs by the modification of the electron transport layer (ETL) adopted as n‐type contact is demonstrated. Specifically, a fluorine‐based plasma treatment prior to perovskite deposition leads to surface fluorination of the TiO2 ETL. The presence of fluorine on the TiO2 surface drastically improves the adhesion between the ALD layer and the methylammonium lead iodide perovskite film, and leads to a more favourable energy band alignment, accompanied by a faster electron carrier extraction at the interface. As consequence of surface fluorination, we observe a significant reduction in the current density‐voltage curve hysteresis with respect to the ALD based reference sample, as well as a remarkable improvement in power conversion efficiency from 4% up to a stable 14.8%. [ABSTRACT FROM AUTHOR]
graphene, epoxy, composite, surface treatment, and thermal conductivity
In this study, in order to improve the thermal and electrical properties of epoxy/graphene nanoplatelets (GNPs), surface modifications of GNPs are conducted using silane coupling agents. Three silane coupling agents, i.e. 2-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane (ETMOS), 3-glycidoxypropyltriethoxysilane (GPTS), and 3-glycidoxypropyltrimethoxysilane (GPTMS), were used. Among theses, GPTMS exhibits the best modification performance for fabricating GNP-incorporated epoxy composites. The effect of the silanization is evaluated using transmission electron microscopy (TEM), scanning electron microscopy, thermogravimetric analysis, and energy dispersive X-ray spectroscopy. The electrical and thermal conductivities are characterized. The epoxy/silanized GNPs exhibits higher thermal and electrical properties than the epoxy/raw GNPs due to the improved dispersion state of the GNPs in the epoxy matrix. The TEM microphotographs and Turbiscan data demonstrate that the silane molecules grafted onto the GNP surface improve the GNP dispersion in the epoxy.