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Eddy currents are induced by rapidly switching currents of the gradient coils in an magnetic resonance imaging (MRI) scanner, which is typically cylindrical in shape; hence, the use of cylindrical coordinates is more numerically efficient. We develop the energy conserved splitting finite-difference time-domain (EC-S-FDTD) scheme in the cylindrical coordinates to estimate the eddy currents. The important feature is that this scheme conserves energy and is unconditionally stable. The transformation results in numerical singularities are formed at the internal boundary, and we formulate methods to handle these singularities and efficiently solve the equations. The accuracy of the scheme and energy conversation property are tested, and the performance of the proposed method will be evaluated using two numerical simulations, cylindrical transmission lines, and eddy currents induced by Z-gradient coils. Our numerical results indicate that current density distribution reflects the differences in the tissues by their dielectric properties and has second-order convergence in time and space while preserving energy conservation.

AISI 410 martensitic stainless steel (MSS) coatings, reinforced with TiC ceramic particles of varying contents (0, 5%, 10% and 15%), have been fabricated by laser cladding technology for the first time in this study. The microstructure evolution and properties of the laser-cladded specimens are carefully investigated by advanced techniques, including XRD, SEM, TEM, EDS, a micro-hardness tester and a ball-on-disc tribological tester. The obtained results show that the as-cladded 410 MSS coating is mainly composed of coarse lath martensite (M), a few austenite (A) and M23C6. After addition of TiC ceramic particles, the lath-shaped M is significantly refined, meanwhile the nano-sized Ti-enriched ceramic precipitates (TiC and Ti(C,N)) are formed in the composite coatings. However, microcracks and pores occur in the laser-cladded coating with addition of TiC up to 15%. It is found that both the microhardness and wear resistance of the coatings are enhanced with an increasing TiC content, and the 10% TiC-reinforced coating exhibits the optimal comprehensive performance, with much higher microhardness and wear resistance in comparison to the TiC-free MSS coating. The remarkable properties of the TiC-reinforced 410 MSS coatings can be mainly ascribed to the synergistic effects of microstructural refinement, nano-precipitation hardening and second-phase strengthening.

Defect-induced charge carrier recombination at the interfaces between perovskite and adjacent charge transport layers restricts further improvements in the device performance of perovskite solar cells (PSCs). Defect passivation at these interfaces can reduce trap states and inhibit the induced nonradiative recombination. Herein, we report a double-sided interfacial passivation via simply evaporating potassium chloride (DIP-KCl) at both the hole transport layer (HTL)/perovskite and perovskite/electron transport layer (ETL) interfaces in inverted planar PSCs. We demonstrate that the bottom KCl layer at the HTL/perovskite interface not only reduces the interfacial defects and improves the interfacial contact, but also leads to increased perovskite crystallinity, while the top KCl layer at the perovskite/ETL interface efficiently passivates the perovskite top surface defects and facilitates electron extraction at this interface. Thus, suppressed nonradiative recombination and faster charge extraction at both interfaces close to the perovskite layer can be achieved by using our DIP-KCl strategy. As a result, inverted PSCs based on DIP-KCl present an increased efficiency from 17.1% to 19.2% and enhanced stability, retaining over 90% of their initial efficiency after aging at maximum power point tracking for 1000 h. This work provides a simple and efficient way for defect passivation to further increase the efficiency and stability of PSCs.

In this work, 18Ni300 maraging steel was successfully fabricated, for the first time, by a laser cladding technique under atmospheric condition. The effects of different aging times (1, 3, 6, and 9 h) at 500 °C on the microstructure and mechanical properties of the as-cladded 18Ni300 maraging steel were carefully characterized and analyzed. The microhardness and tensile strength increase with increasing aging time up to 6 h, and subsequently, decrease with the time extending to 9 h. On the contrary, the elongation is shown a reverse trend. The original 18Ni300 maraging steel exhibits cellular microstructure with an average grain size of 2 µm, composed of martensite and nano-Ti2N particles. After aging treatment, Ni-rich nano-precipitates (Ni3(Mo,Ti) and Ni(Mo,Ti)) together with reverted austenite were formed and promoted with the extension of aging time. The optimal comprehensive performance of the 18Ni300 maraging steel can be obtained by aging 3 h at 500°C, with microhardness of 509 HV0.2, ultimate tensile strength of 1686 MPa, and elongation of 11.5%, respectively. The microstructural mechanisms accounting for the property changes are discussed in detail.

Density function theory (DFT) method was developed and applied for fundamentally understanding the doping effect of various metals (Al, Ti and Cr) on vanadium dioxide (VO2). The substitution doping of Al, Ti and Cr in VO2 could lead to significant changes in electronic structure, band gap and optical property. Different from physical experiments, the DFT method could be utilized for fundamental understandings at an atomic scale. It was found via DFT calculations that: (i) Al doping caused a slightly distorted octahedron in monoclinic VO2(M), and narrowed the band gap of VO2(M) due to the upward shift of the valence band (VB), while Cr doping narrowed the band gap because of the downward shift of the conduction band (CB); (ii) Ti doping slightly widened the band gap of VO2(M); and (iii) the optical reflectivity of VO2(M) decreased after substitution doping low-valent metals (e.g., Al). This study will be beneficial for designing and controlling elemental doping to obtain metal oxide nanocomposites with unique band gap and electronic structure for thermochromic energy saving applications.

This study represents a facile but efficient glycothermal method for synthesis of vanadium dioxide, VO2(B) nanoparticles with various geometries from spheres to rods, flakes or their agglomeration structures, by controlling reaction conditions (e.g., vanadium resources, reducing agents and surfactants). The as-prepared VO2(B) nanoparticles were characterized in microstructure and composition, and also examined in terms of gas sensing performance. It was found that the VO2(B) nanoparticles exhibit a good sensitivity towards alcohols (ethanol, isopropanol, and butanol) and acetone at the optimised operating temperature of 300 °C. The gas sensing performance was further compared with other vanadium oxides investigated previously, such as V2O5, Na1.08V3O8. The plausible gas sensing mechanism of the as-prepared nanoparticles was discussed in detail. This study would expand the family of vanadium oxides that can be made as potential sensors for applications in detecting environmental safety and human health.

Along with the rapidly developed power conversion efficiencies (PCEs), operational stability of perovskite solar cells (PSCs) remains a bottleneck for further commercialization. The instability mai...

In this letter, an alternative data-driven HSI classification model based on CapsNet is proposed rather than recently predominant convolutional neural network (CNN)-based models. To adjust the CapsNet to HSI classification, we tune a new CapsNet architecture with three convolutional layers. The added shallow layer provides higher level features to the primary capsules, which indirectly speeds up the following routing procedure. To guarantee a good convergence of the whole CapsNet, the three shallow layers are initialized by transferring convolutional parameters from a pretrained CNN model. The improved CapsNet-based models with and without vote strategy both achieve significantly superior performance in HSI classification to the state-of-the-art CNN-based methods on real hyperspectral data sets.

Formamidinium lead iodide (FAPbI3)-based perovskite has attracted increasing attention of researchers due to its lower band gap and improved thermal stability. However, it is structurally unstable and easy to phase-transfer at room temperature. Here, we improve the structural stability of perovskite by controlling its orientation diversity. XRD results show that incorporating CsBr into FAPbI3 is effective to adjust the crystal plane stacking. For the first time, an orientation diversity factor (ODF) is identified, and it is found that an increased ODF is propitious to decrease the lattice distortion and relax the microstrain in the crystal, boosting the efficiency and stability of the perovskite solar cells (PSCs). The optimized inverted PSC based on FA0.85Cs0.15PbI2.85Br0.15 achieves efficiency of 17.59% and presents ignored performance decline under continuous light-soaking for 500 h.

Hybrid organic–inorganic perovskite solar cells (PSCs) have a major drawback of instability for long-term operation. Recently, all-inorganic cesium lead halide perovskites have emerged as thermally stable and efficient photovoltaic light absorbers. However, research on the fundamental crystallization behavior of these materials is still far from adequate. In this work, the surface morphology, crystal structure, chemical states and defect/trap conditions of CsPbI2Br film with increasing annealing time have been systematically studied. We highlight a previously unnoted feature that adverse oxidation by traces of water (H2O)/oxygen (O2) in the normally considered nitrogen (N2) atmosphere takes place during the crystal formation process of CsPbI2Br perovskite. The oxidation leads to an evident increase in the defect density in the CsPbI2Br film and remarkably deteriorated the performance of the corresponding PSC. We believe that this work provides good inspiration for the preparation of high-quality perovskite films and the fabrication of highly efficient inorganic PSCs.

Perovskite solar cells (PSCs) have become the front-running photovoltaic technology and have triggered enormous research interest worldwide owing to their ultra-high solar-to-electric power conversion efficiency and low fabrication costs, but their poor intrinsic stability issues still constitute the main obstacles that hinder their rapid commercialization. Herein, we demonstrate that, by carefully designing the modifier's molecular structure, a facile, highly reproducible and scalable surface modification strategy can effectively enhance both the stability and efficiency of inverted PSCs. The most efficient modifier (2-acetylpyridine) can not only passivate the surface traps of the perovskite film but also enhance its stability against moisture by forming a hydrophobic capping layer on top. Accordingly, the efficiency of the inverted PSC has been improved from 16.75% to 20.05% for the best-performing one, which is, to our knowledge, among the highest values for inverted MA-free PSCs. More encouragingly, the stability of the modified devices can also be largely enhanced: the devices retained 95%, 90%, and 91% of their initial efficiencies after storage in the dark in ambient air for 2000 hours, 85 °C thermal aging for 500 hours in the dark, and light soaking at 45 °C for 500 hours, respectively.

This study represents a facile but effective room-temperature strategy for the synthesis of shape/size-controlled cuprous oxide (Cu 2 O) nanoparticles under mild conditions. The proposed synthesis method offers several advantages/novelties including: room-temperature processing, simple operation procedures, controllable shape and size, high yield, and available for scaling up. The effects of the pertinent variables on the particle formation and growth have been investigated, such as concentration of copper ions (Cu 2+ ), surfactants, reducing agents, and the molar ratios among variables. The composition, microstructure and optical properties were then characterized using advanced techniques. It was found that the use of different surfactants may result in significant morphology changes from spheres to octahedrons and/or wires under the reported conditions. To enhance photocatalytic performance in dye degradation, the Cu 2 O nanoparticles could be further surface decorated by titanium dioxide (TiO 2 ) to form heterogeneous nanocomposites that can improve the electron-hole separation. This study may be useful to develop simple but general approaches to obtain cuprous/copper oxides and other hybrid semiconductor nanostructures with structure and functional control for catalysis and sensing applications.

Based on the fast development of Internet and big data, how to pick out a high-quality service composition quickly from large qualities of services, and meet users’ needs have become a hotspot in service composition research. Service composition optimization is a classic NP hard problem. A modified Beetle Antennae Particle Swarm Algorithm was proposed in this paper and it was applied in web service composition optimization. The author introduced Beetle Antennae Searching Algorithm into the modified Particle Swarm Algorithm, modified position update formula, adopted the modified Nonlinear Dynamic Trigonometric Learning Factors to control the particles’ expanding capacity and global convergence capability and incorporated the modified Secondary Oscillation factors which increased the searching precision of the algorithm and global searching ability. The experimental results under real data set indicated that the modified Beetle Antennae Particle Swarm Algorithm proposed in this paper could settle large-scale web service composition optimization problems in cloud environment, had good global searching ability, comparatively faster convergence speed and needed less time cost.

Martensitic stainless steel (MSS) coatings with different vanadium (V) contents (0&ndash, 1.0 wt%) by microalloying have been successfully fabricated utilizing a unique laser cladding technique. The microstructure and properties of the resulting MSS coatings, with and without element V addition, have been carefully investigated by various advanced techniques, including XRD, SEM, TEM, microhardness tester, universal material testing machine, and electrochemical workstation. It was found that the V-free coating was mainly composed of martensite (M) and ferrite (F), trace M23C6 and M2N, while the V-bearing coatings consisted of M, F, M23C6, and VN nano-precipitates, and their number density increased with the increase of V content. The V microalloying can produce a significant impact on the mechanical properties of the resulting MSS laser-cladded specimens. As the V content increased, the elongation of the specimen increased, while the tensile strength and microhardness increased firstly and then decreased. Specifically, the striking comprehensive performance can be optimized by microalloying 0.5 wt% V in the MSS coating, with microhardness, tensile strength, yield strength, and elongation of 500.1 HV, 1756 MPa, 1375 MPa, and 11.9%, respectively. However, the corrosion resistance of the specimens decreased successively with increasing V content. The microstructure mechanisms accounting for the property changes have been discussed in detail.

This study demonstrates a simple hydrothermal method while can be generalized for controllable synthesis of noble metallic carbonaceous nanostructures (e.g., Au@C, Ag@C) under mild conditions (180–200 °C), which also provides a unique approach for fabricating hollow carbonaceous structures by removal of cores (e.g., silver) via a redox etching process. The microstructure and composition of the as-achieved nanoparticles have been characterized using various microscopic and spectroscopic techniques. Cetyltrimethylammonium bromide (CTAB), serving as a surfactant in the reaction system, plays a key role in the formation of Ag@C, Au@C nanocables, and their corresponding hollow carbonaceous nanotubes in this work. The dynamic growth and formation mechanism of carbonaceous nanostructures was discussed in detail. And finally, laser-induced photothermal property of Au@C nanocomposites was examined. The results may be useful for designing and constructing carbonaceous metal(s) or metal oxide(s) nanostructures with potential applications in the areas of electrochemical catalysis, energy storage, adsorbents, and biomedicine. Graphic abstract This study demonstrate a facile hydrothermal synthesis of noble metal carbonaceous nanocomposites (e.g., Au@C) with simple procedures under mild conditions, which can be25expanded as a general method for preparing diverse carbonaceous core-shell nanoparticles. The Au@C carbonaceous nanostructures exhibit interesting UV-Vis properties dependent upon shell thickness.

High-temperature corrosion resistance is a big issue for structural materials in molten salt reactors. A simple but effective laser cladding technique has been utilized for producing a compact AlN coating on Hastelloy-N alloy. The results show that the laser-cladded AlN coating improves the compatibility of Hastelloy-N alloy in LiF-NaF-KF molten salt at 900 °C significantly. The uncoated Hastelloy-N alloy is composed of γ-Ni and M6C phases, showing a typical intergranular corrosion with a precipitation of new Cr9Mo21Ni20 phase after corrosion. In contrast, the AlN coating exhibits a silghtly unifrom corrosion and protects the Hastelloy-N substrate effectively. The laser-cladded specimes are composed of γ-Ni and AlN before and after corrosion. The possible reasons for the discrepancy in the corrosion behavior between uncoated and coated specimens are discussed in this job.

Inorganic cesium lead halide perovskites , as alternative light absorbers for organic−inorganic hybrid perovskites, have attracted more and more attentions due to their superb thermal stability for photovoltaic applications. However, the device performance, as reported to date, is dispirited as it is still a challenge to prepare inorganic perovskite films with both sufficient absorbance and high quality. Here, solvent engineering is conducted, and solvent composition is found largely influence the crystallization progress and film morphology. Combined with anti-solvent-extraction technology, homogenous and pinhole-free CsPbI 2Br films have been prepared with optimized solvent of DMF/DMSO mixture with the volume ratio of 3:2. The inverted planar device with a 410 nm-thick CsPbI2Br absorber achieves a power conversion efficiency of 9.14%. Furthermore, the as-prepared perovskite and its based device exhibit good stability under high temperature stress and continuous light soaking at maximum power point tracking conditions (100 mW cm−2, 500 h).

A novel enzymatic biofuel cell (EBFC) mediated by pH change of solution has been designed with an amphiphilic polystyrene-block-poly(4-vinylpyrdine) (PS-b-P4VP) as “ON” and “OFF” switch and laponite-supported enzyme hybrids as biocatalyst. The bioanode and biocathode were successfully established by sequential assembly of PS-b-P4VP and laponite-supported glucose oxidase or laccase on glassy carbon electrode, respectively. Consecutively switching of the solution pH below and above the pKa of P4VP, the reversible electrostatic interaction transformation between repulsion and attraction of PS-b-P4VP toward electrochemical probe was realized to control the “ON” and “OFF” behavior of EBFC. When the pH of reaction solution below the pKa (such as pH 4.5), the protonated copolymer could allow negatively charged probe access to the catalytic centers of enzymes, leading to the enhanced electrochemical reaction and electron transfer of EBFC (set as “ON” state); Above the pKa (such as pH 7.0), the cell reaction was blocked because the lone pair electron of pyridine unites resulted from PS-b-P4VP could effectively inhibit the reactant transmission of electrochemical probe (set as “OFF” state). The developed EBFC exhibited an obvious “ON-OFF” switching property at both pH values. At “ON” state, the open circuit potential (Ecellocp) and maximal power output density (Pmax-ON) reached to 0.42 V and 3.49 μW cm−2, while at “OFF” state, the corresponding Ecellocp and Pmax-OFF were only 0.22 V and 0.39 μW cm−2. Moreover, this rapidly repeated switching behavior could open an alternative way for the fabrication of tunable EBFC, and showed great prospect in biomedical field.

A large number of previous studies demonstrate that excess PbI2 in perovskite films is essential for solar cells to achieve high efficiency due to defect passivation, but few studies consider its negative impact on the devices' long-term stability. Herein, we introduced CaI2 instead of PbI2 with much less additive content into the CH3NH3PbI3 (MAPbI3) film and obtained a dense, uniform and surface-smooth morphology with much enlarged crystal grains. It has been demonstrated that addition of only 0.5% CaI2 additive to MAPbI3 is enough to enlarge the average grain size from 260 nm to 550 nm; accordingly, the defect density is decreased from 5.76 × 1016 cm−3 to 3.35 × 1016 cm−3 and the photoluminescence (PL) lifetime is increased from 65 ns to 133 ns; as the reference, addition of 5% PbI2 additive to MAPbI3 results in an average grain size of 410 nm, a defect density of 4.06 × 1016 cm−3 and a PL lifetime of 98 ns. In all of these key parameters, CaI2 as a new passivator of the MAPbI3 film, is found to be more effective than conventional PbI2. As a consequence, the champion cell based on MAPbI3(CaI2)0.005 achieved a high efficiency of up to 19.3%, superior to those based on pristine MAPbI3 (16.1%) and MAPbI3(PbI2)0.05 (18.0%). In addition, 10 times less additive of CaI2 than PbI2 made the perovskite film much less deviated from the ideal stoichiometry of MAPbI3, which is found to be essential for the device to achieve long-term stability.

18Ni300 maraging steel with different TiC contents (0−10 wt.%), for the first time, have been fabricated by a direct laser deposition (DLD) technique. The microstructure and properties of the as-deposited and heat-treated samples have been carefully investigated. The obtained results show that the original 18Ni300 maraging steel exhibits extremely fine cellular microstructure with an average diameter of 3.7 μm, composed of martensite (M) and Ti2N. In contrast, the microstructure of the TiC-reinforced composites is significantly refined, in which the volume fraction of TiC formed with different morphologies varies with the TiC addition content. However, some cracks exist in the composite sample with the TiC addition up to 10 wt.%. The average microhardness of the as-deposited samples increases initially and then decreases with increasing TiC content, and the maximum microhardness (444 HV0.2) is obtained after adding 5 wt.% TiC. In addition, the sample with 5 wt.% TiC has been experienced a solution treatment at 850 ℃ for 1 h and then a subsequent aging treatment at 500 ℃ for 3 h. A number of nano-precipitates Ni3(Mo,Ti) and a few austenite are formed, which are dispersed in the martensite matrix after the heat treatment. This results in a high microhardness of 576 HV0.2 and a low wear rate of 1.37 × 10-6 mm3/(N·m), compared with those of the TiC-free sample (368 HV0.2 and 5.61 × 10-5 mm3/(N·m)), respectively. The possible microstructural mechanisms accounting for the property changes of the TiC-reinforced 18Ni300 maraging steel have been discussed in detail.

We propose a novel data-driven matching cost for dense correspondence based on sparse theory. The ability of sparse coding to selectively express the sources of influence on stereo images allows us to learn a discriminative dictionary. The dictionary learning process is incorporated with discriminative learning and weighted sparse coding to enhance the discrimination of sparse coefficients and weaken the influence of radiometric changes. Then, the sparse representations over the learned discriminative dictionary are utilized to measure the dissimilarity between image patches. Semi-global cost aggregation and postprocessings are finally enforced to further improve the matching accuracy. Extensive experimental comparisons demonstrate that: the proposed matching cost outperforms traditional matching costs, the discriminative dictionary learning model is more suitable than previous dictionary learning models for stereo matching, and the proposed stereo method ranks the third place on the Middlebury benchmark v3 in quarter resolution up to the submitting, and achieves the best accuracy on 30 classic stereo images.

Stereo matching between binocular stereo images is fundamental to many computer vision tasks, such as three-dimensional (3D) reconstruction and robot navigation. Various structures of real 3D scenes lead stereo matching to be an old yet still challenging problem. In this study, the authors proposed a novel adaptive support weights technique which exploits the hierarchical information provided by multilevel segmentation to preserve the robustness to imaging conditions and spatial proximity in cost aggregation. Besides, a generalisable cost refinement strategy is designed to remove the matching ambiguity in large weakly textured regions. The proposed strategy utilises both the fluctuation of the filtered cost volume and the colour information to further improve the matching accuracy. Experimental results of 50 stereo images demonstrate the effectiveness and efficiency of the proposed method. Furthermore, a systematic evaluation is developed to assess the conventional steps in local stereo methods and then reliable suggestions are given to the beginners and researchers outside the stereo matching field.

The ash melting temperature of coal ash has an important effect during the fluidized bed combustion and gasification process, which affects the slagging and deposition characteristics of the boiler. Experiments on the effects of chemical components on the ash fusion behaviors have been completed on the ash fusion temperatures (AFTs) analyzer under typical gasification and combustion atmospheres. Meanwhile, calculations on the variation of minerals in ash with ash composition were conducted using the FactSage software. The results indicated that the AFTs under gasification were a little higher than those under the combustion atmosphere. On increasing the Fe2O3, CaO, and Na2O contents under the combustion and gasification atmospheres, the four temperatures deformation temperature (DT), softening temperature (ST), hemispherical temperature (HT), and flow temperature (FT) decreased dramatically and the generation and transformation of minerals occurred. The iron-containing minerals, such as hercynite and faya...

In this paper, we develop a new groundwater pollution control by finding the optimal amounts of fluxes for disposals, where the optimization objective function is proposed by considering the overall effects caused by pollution, abatement costs and pollution taxes. The proposed optimal control model is subject to the flow and transport groundwater equations in porous media. More specifically, we use the splitting scheme and the second-order improved-upwind method to simulate the flow and transport processes in the groundwater system in porous media. We then integrate the simulated results with an optimization problem which minimizes the pollutant concentration deviation, abatement cost and pollution tax simultaneously. The optimization problem is solved by the constrained difference evolution (DE) optimization algorithm. The performance of the proposed optimal control model is evaluated on two synthetic simulations: one on an aquifer with a simple geometry and with constant disposal fluxes, and the other on a more realistic-shaped aquifer with fluxes varying piecewise in time. The developed source optimal control model and its algorithm can be applied to large scale applications of groundwater pollution control on aquifers.

In this work, a metal-organic frameworks material MIL-88 was prepared easily using solvent-thermal method, and was first found to have catalytic activities similar to those of biological enzymes such as catalase and peroxidase. The material was characterized by XRD, SEM, TEM, EDX, FT-IR techniques and an N-2 adsorption method. It exhibited peroxidase-like activity through catalytic oxidation of the peroxidase substrate 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of H2O2, producing a blue-colored solution. Under optimal conditions, the absorbance at 652 nm is linearly correlated with the concentration of H2O2 from 2.0 x 10(-6) mol/L to 2.03 x 10(-5) mol/L (R-2 = 0.981) with a detection limit of 5.62 x 10(-7) mol/L (S/N = 3). More importantly, a sensitive and selective method for ascorbic acid detection was developed using this material as a catalyst. The analytical method for ascorbic acid detection was observed to have a linear range from 2.57 x 10(-6) mol/L to 1.01 x 10(-5) mol/L (R-2 = 0.989)-with a detection limit of 1.03 x 10(-6) mol/L (S/N =3). This work suggests MOFs have advantages of preparing biomimetic catalysts and extends applications of the functional MOFs in the field of biosensor. (C) 2017 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.

Al-based amorphous-nanocrystalline composite coatings were prepared by laser cladding Al95-xCuxZn5 (x = 5, 10, 15, at.%) powders on AZ80 magnesium alloy under a low-temperature water cooling condition. The microstructural observations indicate that all the cladding layers exhibit good metallurgical bonding to the substrates while the morphology of the cladding layer varies with the Cu content. The microstructure and properties of the Al85Cu10Zn5 (x = 10, at.%) coating and the substrate were carefully characterized and analyzed. The XRD analysis and TEM observations show that the Al85Cu10Zn5 cladding layer is constituted of amorphous phase, nanocrystallines and ternary intermetallics Mg32Al47Cu7, τ-Mg32(Al,Zn)49, AlMg4Zn11 and S-Al2CuMg. The surface performances of the AZ80 substrate are greatly improved by the Al85Cu10Zn5 cladding layer. The average hardness of the Al85Cu10Zn5 layer is 364 HV0.05, which is about 4 times higher than that of the substrate (∼86 HV0.05), and the relative wear resistance of the Al85Cu10Zn5 cladding layer is 5.5 times better than that of the substrate. Meanwhile, the corrosion potential (Ecorr) is increased by 276.2 mV and the corrosion current density (Icorr) is decreased by two orders of magnitude. In addition, the reasons accounting for the improvements of the mechanical properties and corrosion resistance are elucidated accordingly.

Bathocuproine (BCP) buffer layer has been commonly used in inverted p–i–n perovskite solar cells (PSCs) for high performance, but its working mechanism has not been thoroughly elucidated. Here, a series of devices have been fabricated with controlled thicknesses of BCP layers deposited by thermal evaporation. With the aid of J–V data fitting by a single-diode model, the effect of BCP layer thickness on the device performance has been identified. An optimal power conversion efficiency (PCE) up to 17.9% has been obtained for the device with a critical BCP thickness of 5 nm, thanks to the formation of ohmic contact and reduction of interfacial charge recombination. While if the BCP layer is too thin or too thick, charge accumulation will emerge due to different mechanisms and lead to device performance degradation, which have been clearly confirmed by capacitance–voltage (C–V) characteristic displaying a peak capacitance at a certain bias region under illumination. The insertion of such a critical thin BCP layer between PCBM and Ag also resulted in long-term stability improvement of the devices, of which the T80 lifetime increased from ∼6 hours to ∼50 hours in ambient air. This work gives insight into improving PSCs' performance through buffer layer's optimization, and the measurement of C–V characteristic provides a new clue to detect the defection of photovoltaic device associated with charge accumulation.

Hyperspectral image (HSIs) with abundant spectral information but limited labeled dataset endows the rationality and necessity of semi-supervised spectral-based classification methods. Where, the utilizing approach of spectral information is significant to classification accuracy. In this paper, we propose a novel semi-supervised method based on generative adversarial network (GAN) with folded spectrum (FS-GAN). Specifically, the original spectral vector is folded to 2D square spectrum as input of GAN, which can generate spectral texture and provide larger receptive field over both adjacent and non-adjacent spectral bands for deep feature extraction. The generated fake folded spectrum, the labeled and unlabeled real folded spectrum are then fed to the discriminator for semi-supervised learning. A feature matching strategy is applied to prevent model collapse. Extensive experimental comparisons demonstrate the effectiveness of the proposed method.

Long-term stability remains a key issue impeding the commercialization of halide perovskite solar cells (HPVKSCs). The diffusion of molecules and ions causes irreversible degradation to photovoltaic device performance. Here, we demonstrate a facile strategy for producing highly stable HPVKSCs by using a thin but compact semimetal Bismuth interlayer. The Bismuth film acts as a robust permeation barrier that both insulates the perovskite from intrusion by undesirable external moisture and protects the metal electrode from iodine corrosion. The Bismuth-interlayer-based devices exhibit greatly improved stability when subjected to humidity, thermal and light stresses. The unencapsulated device retains 88% of its initial efficiency in ambient air in the dark for over 6000 h; the devices maintain 95% and 97% of their initial efficiencies after 85 °C thermal aging and light soaking in nitrogen atmosphere for 500 h, respectively. These sound stability parameters are among the best for planar structured HPVKSCs reported to date., Long term stability is a major barrier for the commercialization of halide perovskite solar cells. Here Wu et al. demonstrate that a chemically inert and structural impermeability bismuth electrode interlayer greatly increases the stability of unencapsulated perovskite solar cells under harsh conditions.

Efficient and stable parallel perovskite solar module is achieved by slot-die coating., Perovskite solar cells have emerged as one of the most promising thin-film photovoltaic (PV) technologies and have made a strong debut in the PV field. However, they still face difficulties with up-scaling to module-level devices and long-term stability issue. Here, we report the use of a room-temperature nonvolatile Lewis base additive, diphenyl sulfoxide(DPSO), in formamidinium-cesium (FACs) perovskite precursor solution to enhance the nucleation barrier and stabilize the wet precursor film for the scalable fabrication of uniform, large-area FACs perovskite films. With a parallel-interconnected module design, the resultant solar module realized a certified quasi-stabilized efficiency of 16.63% with an active area of 20.77 cm2. The encapsulated modules maintained 97 and 95% of their initial efficiencies after 10,000 and 1187 hours under day/night cycling and 1-sun equivalent white-light light-emitting diode array illumination with maximum power point tracking at 50°C, respectively.

In order to use finite element simulation to design electromechanical devices, self-consistent full tensor material properties are needed. The IEEE resonance technique usually requires more than 5 different geometry samples to complete the full tensor characterization, but the poling degree will depend on the sample geometry in relaxor-base ferroelectric single crystals. Hence, it is very difficult to obtain self-consistent full tensor properties using multiple samples. In this study, we used only one sample to determine the whole set of materials properties for single domain PZN–6.5%PT single crystals by combining the ultrasonic pulse-echo (UPE) method and the resonance ultrasonic spectroscopy (RUS) for the elastic and piezoelectric coefficients and the impedance analyzer for dielectric measurements. Comparison with other reported results show the advantage of our methodology and such self-consistent date set would facilitate fundamental studies on domain engineering technique as well as device design optimization using finite element software.

Plasma nitriding and plasma-assisted PVD duplex treatment was adopted to improve the load-bearing capacity, fatigue resistance and adhesion of the AlTiN coating. Ion etch-cleaning was applied for better adhesion before plasma nitriding. After plasma nitriding Ti interlayer was in-situ deposited by high power impulse magnetron sputtering (HIPIMS), followed by the AlTiN coating through in-situ deposition by advanced plasma-assisted arc (APA-Arc). The microstructure and properties of the duplex-treated coating were carefully characterized and analyzed. The results show that the thicknesses of the nitriding zone, the γ′-Fe 4 N compound layer, the Ti interlayer and the AlTiN top layer with nanocrystalline microstructures are about 60 μm, 2–3 μm, 100 nm and 6.1 μm, respectively. The nitriding rate is about 30 μm/h and the AlTiN coating deposition rate reaches 6.1 μm/h. The interfacial adhesion of the Ti/AlTiN coating is well enhanced by ion etch-cleaning and a Ti interlayer, and the load-bearing capacity is also improved by duplex treatment. In addition, the instinct hardness of the Ti/AlTiN coating reaches 3368HV 0.05 while the wear rate coefficient of 5.394×10 −8 mm −3 /Nm is sufficiently low. The Ti/AlTiN coating, which possesses a high corrosion potential ( E corr =−104.6 mV) and a low corrosion current density ( i corr =4.769 μA/cm 2 ), shows highly protective efficiency to the substrate.

In the present work, martensitic stainless steel (MSS) coatings with niobium (Nb) contents of 0–1.0 wt%, combining high strength and ductility with improved corrosion resistance, have been developed and fabricated by a laser cladding technique. The effects of Nb-microalloying on the microstructure and properties of the laser-cladded MSS coatings have been carefully investigated. The results show that the original Nb-free MSS coating is mainly composed of martensite and austenite, along with nano-M2N and M23C6. With the addition of Nb, the lath-shaped martensite is refined, and an increasing occurrence of nano-sized Nb-enriched precipitates (NbC and Nb(C,N)) is observed in the coatings with increasing Nb content. With the successive addition of Nb, the microhardness of the specimens is found to increase from the 437 HV0.2 of the Nb-free coating to the 502 HV0.2 of the 1.0 wt% Nb-alloyed coating. At the same time, the tensile mechanical properties and corrosion resistance are found to increase with increasing Nb content of up to 0.5 wt% and subsequently decrease with further addition of Nb. Thus, the addition of 0.5 wt% Nb provides a laser-cladded MSS coating that is superior to those reported in the literature, combining the optimum tensile properties of high strength (1780 MPa) and high ductility (EL = 10.5%) along with excellent corrosion resistance. The remarkable overall properties of the as-prepared MSS coatings can be ascribed to the combined effects of solid solution, microstructural refinement, and nano-precipitation.

The nitrogen (N) alloying in traditional bulk martensitic stainless steel (MSS) necessitates high-pressure and high-temperature treatment because of its extremely low solubility. Herein, we report a novel strategy for in-situ nitriding MSS coating with N content up to 0.14 wt% by laser cladding technique without harsh conditions. The resulting coating is composed of martensite, austenite, nano-precipitates M23C6 and M2N, which exhibits striking mechanical properties with tensile strength of 1900 MPa and elongation of 7.3% as well as excellent corrosion resistance, exceptionally superior to the reported laser cladded MSS coatings. This may be ascribed to the combination impacts of grain refinement, nano-precipitation, interstitial solid solution and dislocation strengthening.

The corrosion protection of Hastelloy-N alloy in LiF-NaF-KF (commonly referred to as FLiNaK) molten salt has been developed by pure Ni and Co coatings using the laser cladding technique. An immersion experiment with samples was performed in molten FLiNaK salt at 900 &deg, C for 100 h. It was found that the corrosion rates of the pure Ni-coated specimen and the pure Co-coated specimen are 39.9% and 35.7% of that of Hastelloy-N alloy, respectively. A careful microstructural characterization indicates that a selective dissolution of the elemental Cr occurred in the surface of bare Hastelloy-N alloy, showing a severe intergranular corrosion. For pure metal-coated specimens, in contrast, only metal oxide formed during the laser cladding process dissolved into the molten fluoride salt. The dense pure metal (Ni or Co) coatings exhibit a slightly general corrosion and protect the Hastelloy-N substrate effectively. The possible corrosion mechanism for both coated and uncoated Hastelloy-N under the current experimental condition are discussed in this work.

The co-processing of hazardous waste in cement kiln can eliminate a large number of hazardous wastes, but the excessive existence of chlorine will affect normal operation of cement kiln. In this study, the partition of Cl in flue gas, fly ash and residual solid under different experiment conditions was obtained by using tubular furnace to incinerate mixtures of rectification residue and raw meal. The chlorine content in flue gas was determined using ion chromatography and the chlorine content in fly ash and residual solid was measured by high temperature combustion hydrolyzing-ion chromatography. The results showed that chlorine mainly existed in flue gas and residual solid, and only less than 3.5% of chlorine existed in fly ash. The incineration temperature had a significant effect on the distribution of chlorine in each part. The higher the incinerating temperature, the greater the proportion of chlorine in flue gas and fly ash. While temperatures were higher than 1300 °C, the proportion of chlorine in all parts remained basically unchanged, roughly 18:14:1. With the increase of the retention time, the proportion of chlorine in the residual solid decreased gradually, and the proportion of chlorine in the flue gas increased gradually. The distribution ratio of chlorine in each part remained unchanged after about 30 min. In addition, the chlorine content of the sample and the air flow rate had a relatively slight effect on the partition of chlorine. Based on these experimental results, some suggestions on the co-processing of hazardous waste in cement kiln were put forward.

In this paper, we present an alternative parametric active contour (APAC) model for 3D lunar crater detection with shadow and overexposure problem. Compared with the traditional parametric active contour model, the main difference is that we construct a Gaussian attractive force field between two initial curves for each crater proposal, which enables the two initial curves to mutually convey message to each other and avoids local optimum. In addition, we introduce the elevation information estimated from CCD stereo images into the external energy term of the APAC model, which helps to remove false craters by providing the geometric properties of craters. The proposed method is evaluated on eight pairs of stereo images with different numbers, scales and illuminations captured by Chang'E-I satellite, which demonstrates its effectiveness and efficiency.

Gold nanorods (AuNRs) have attracted high attention because of their multifunctions and potential applications in optical, electronic, catalytic and biomedical areas. This study demonstrates a key role of silver (Ag) atoms/clusters, experimentally and theoretically, in the formation and growth of AuNRs. It was found that the addition of silver salt (silver nitrate) can preferably deposit on certain Au crystalline {100} and/or {110} facets to affect the stacking of Au atoms when form and grow to AuNRs in the reported reaction system, resulting in slower atomic stacking on these two {100} and {110} facets but regular growth on the {111} facets. If no use of silver salt(s), gold nanospheres rather than nanorods were obtained in such a reaction system. It was found, by theoretical simulations (molecular dynamic method, MD), that Ag atoms can be oxidized to Ag+ ions by AuCl4 − ions and exist in a short lifetime, which finally diffuses out from the Au crystal structure. The findings would be useful for better understanding the role of Ag in the formation and growth of AuNRs with crystal facet control, which will be beneficial for catalytic and gas sensing applications that often require highly exposed crystalline facets.

Post-treatment is crucial to improve the comprehensive performance of laser-cladded martensitic stainless steel coatings. In this work, a low-temperature tempering treatment (210 °C), for the first time, was performed on the laser-cladded AISI 420 martensitic stainless steel coating. The microstructure and properties of the pre- and post-tempering specimens were carefully investigated by XRD, SEM, TEM, a micro-hardness tester, a universal material testing machine and an electrochemical workstation. The results show that the as-cladded AISI 420 stainless steel coating mainly consisted of martensite, austenite, Fe3C and M23C6 carbides. The phase constituent of the coating remained the same, however, the martensite decomposed into finer tempered martensite with the precipitation of numerous nano-sized Fe3C carbides and reverted austenite in the as-tempered specimen. Moreover, a slight reduction was found in the micro-hardness and tensile strength, while a significant increase in elongation was achieved after tempering. The fractography showed a transition from brittle fracture to ductile fracture accordingly. The as-tempered coating exhibited a striking combination of mechanical properties and corrosion resistance. This work can provide a potential strategy to enhance the overall properties of the laser-deposited Fe-based coating for industrial applications.

In this paper, we proposed a novel method to estimate the normal information of the unorganized point cloud, which plays an essential part in 3D reconstruction. The original point cloud is firstly divided into cubes with different sizes by the octree method. Then, we fit algebraic sphere in each cube instead of planar surface to improve the accuracy of normal estimation. Finally, the raw normals are refined by a weighting function which increases along with the depth of octree. For evaluation, we compute the intersection angles between the estimated normals and the corresponding groundtruth. Besides, the estimated normals are also plugged into the Poisson surface reconstruction algorithm for intuitive comparison. Experimental results demonstrate the effectiveness of our normal estimating methods. Moreover, the strategy that normal estimation after division saves much more computing time, which promises the efficiency of our method.

In this paper, we focus on the shadow problem of the lunar surface, which hinders the implementation of visual tasks and visual processing for moon exploration projects. A random walker model is firstly applied to detect the shadowed pixels in lunar craters. Then, the detected shadows are removed by rectifying the illumination coefficients and detail coefficients, which are obtained by using the multi-scale decomposition technique. The proposed algorithm is evaluated on three groups of CCD images and the corresponding DEM data. Satisfactory results, which achieve comparative illumination yet preserve enough details, demonstrate the effectiveness of the proposed algorithm.

Stimulus-responsive microporous solid thin films were successfully fabricated by simple molecular self-assembly via an amphiphilic block polymer, polystryene-b-polyacrylic acid (PS-b-PAA). The solid thin films exhibit different surface morphologies in response to external stimuli, such as environments with different pH values in aqueous solutions. The experiments have successfully applied atomic force microscope (AFM) technology to observe in-situ surface morphological changes. There is a reversible evolution of the microstructures in buffer solutions over a pH range of 2.4-9.2. These observations have been explained by positing that there is no conventional PAA swelling but that the PAA chains in the micropores stretch and contract with changes in the pH of the solution environment. The hydrophobicity of the solid thin film surface was transformed into super-hydrophilicity, as captured by optical contact angle measurements. The stimulus-responsive dynamics of pore sizes was described by a two-stage mechanism. A promising electrochemical application of this film is suggested via combination with an electrochemical impedance technique. This study is aimed at strategies for the functionalization of stimulus-responsive microporous solid thin films with reversible tunable surface morphologies, and exploring new smart materials with switch-on/switch-off behavior.

On the surface of zirconium alloy, the TiN coatings with and without Cr interlayer were prepared in the N2/Ar mixed gas atmosphere by physical vapor deposition technology. The coatings morphology, micro-composition of surface particles, surface roughness, phase constituent and high-temperature oxidation resistance were characterized by scanning electron microscope (SEM), energy dispersive spectrometer (EDS), roughness measuring instrument, x-ray diffractometer (XRD) and chamber electric furnace, respectively. The results show that, in comparison with the TiN coatings, the gray large particles increase in volume and the striated gullies reduce significantly for the Cr/TiN coatings. With the presence of Cr interlayer, the roughness of coatings increases, TiN (111) plane shows a weak growth, and the average grain size becomes small, while the average compressive strain increases. After the high-temperature oxidation test, there is a dense mixture of TiO2 and Cr2O3 on the surface of the Cr/TiN coatings which is continuous and complete without any defects such as cracks and holes. The Cr/TiN coatings enhanced the oxidation resistance of zirconium substrate, evidenced with 1/3 oxidation weight gain of that of the zirconium alloy. These results demonstrate the effectiveness of Cr/TiN coating as a protective coating on the zirconium alloy under extreme conditions.

Time-varying coherence is a powerful tool for revealing functional dynamics between different regions in the brain. In this paper, we address ways of estimating evolutionary spectrum and coherence using the general Cohen's class distributions. We show that the intimate connection between the Cohen's class-based spectra and the evolutionary spectra defined on the locally stationary time series can be linked by the kernel functions of the Cohen's class distributions. The time-varying spectra and coherence are further generalized with the Stockwell transform, a multiscale time-frequency representation. The Stockwell measures can be studied in the framework of the Cohen's class distributions with a generalized frequency-dependent kernel function. A magnetoencephalography study using the Stockwell coherence reveals an interesting temporal interaction between contralateral and ipsilateral motor cortices under the multisource interference task.