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The thick titanium nitrides coating was fabricated on LZ91 alloy by surface mechanical nano-alloying (SMNAT) combined with gas nitriding. Experimental results showed that a nanostructured titanium ...

In this paper, the removal of the sulfide layer formed on an FV(520)B stainless steel in the simulated environment of air compressor blade service conditions in a reaction kettle by arc plasma was investigated to explore the mechanism and technology of the sulfide layer removed by arc plasma from a blade surface. The sulfide lattice energy is studied by using the Born Haber cycle. Besides, the energy balance of the removal process is calculated. The treated surface morphology of samples was analyzed by scanning electron microscopy and energy dispersive spectrometer. The results indicate that the energy of the arc spot is enough to evaporate the sulfide film. Due to the different electronic work functions, an arc spot is first formed on the sulfide film, and then the voltage signal is segmented during the removal process. The voltage signal in the removal process can remove sulfide without harming the metal matrix. Besides, the increase in current can improve the removal efficiency and the surface roughness of the sample. It can be revealed, by analyzing the surface composition of samples with different currents, that the sulfur content is very low, indicating that it is feasible to remove the sulfide layer by arc spot plasma.

Deceptive reviews on Web are a common phenomenon and how to detect them has a very important impact on products, services, and even business policies. In order to filter out deceptive reviews more accurately, a new model called Sentence Joint Topic Sentiment Model (SJTSM) is presented in this paper, which incorporates the sentence structure of reviews and the sentiment label information of words based on Latent Dirichlet Allocation (LDA) model to extract the review features. The proposed model employs Gibbs algorithm to estimate the maximum likelihood parameters and takes the vector of topic-sentiment distribution as the review features. Then a voting system of multiple-classifier, which takes the extracted review feature vector as its input is designed to realize the classification of deceptive review detection. The comparative experiments on different public datasets with other existing methods based on LDA model show that the new classifying system based on SJTSM model can achieve more satisfying classification results on deceptive review detection.

High-performance fabrics with excellent electrical conductivity are increasingly attractive in modern industries. In this study, we report an electrically conductive silver/polyimide fabric (Ag/PIF) composite fabricated by combining an O 2 plasma pretreatment and a spray-assisted electroless plating (SAELP) technique. O 2 plasma treatment is firstly employed to roughen the surface of PIF and introduce functional aldehyde or ketone groups, which can act as a reducing agent and facilitate an even nucleation initiation of silver nanoparticles (Ag NPs) on the surface of the PIF. A silver ion solution and a reducing agent are then mixed evenly and sprayed to the PIF immediately to obtain Ag/PIF composites. The effects of O 2 plasma treatment and SAELP duration on the Ag/PIF composites are investigated and discussed. The results demonstrate that the silver layer is coated on the PIF uniformly and densely with a surface resistance of 0.1 Ω/sq. The first decomposition temperature of the Ag/PIF composites is up to 600 °C, indicating excellent thermal stability. The enhanced adhesion between Ag NPs and PIF endows the composites excellent fastness and superior flexibility. This work gives a new strategy for fabricating flexible, electrically conductive functional metal coated fabrics with high-performance properties in an efficient, facile and scalable way.

Effect of crystallographic orientations on the corrosion resistance of the Fe-17Cr ferritic stainless steel sheets was investigated by electron backscatter diffraction and electrochemical measurements. Nearly homogeneous {111}〈112〉 γ-fiber recrystallization texture is produced in the Fe-17Cr ferritic stainless steel sheets. Comparison between the inverse pole figure orientation map and scanning electron microscopy microstructures etched by aqua regia reveals that the severest corrosion occurs on the sheet rolling surface where {111} crystal plane dominates. Electrochemical measurements demonstrate that the plane perpendicular to transverse direction displays the lowest corrosion current density. This indicates that this plane, where {110} plane dominates, exhibits the best corrosion resistance.

The effects of Nb addition on the microstructure and corrosion resistance of the as-rolled Ti-stabilized Fe-17Cr ferritic stainless steels were investigated by optical microscopy, scanning electron microscopy, X-ray diffraction, pitting tests, and electrochemical measurements. TiN precipitate tends to form in the microstructure of Ti-stabilized Fe-17Cr ferritic stainless steel. After 0.1 wt. % Nb addition, (Ti, Nb) (C, N) composite precipitates with MgO and Al2O3 core form in the microstructure. After adding 0.1 wt. % Nb, the corrosion rate of the Ti-stabilized Fe-17Cr ferritic stainless steel in FeCl3 solution is decreased significantly. The corrosion current densities decrease in HNO3, NaOH, and NaCl solutions, and the pitting corrosion potentials can be improved in NaCl solution for the Fe-17Cr ferritic stainless steel with 0.1 wt. % Nb addition.

The effect of Sc on the microstructure and mechanical properties of Al–Si–Mg–Cu–Ti alloy was investigated. Results obtained in this research indicate that, with increasing Sc content, the microstru...

This paper presents an experimental investigation on the knittability of various polyimide (PI) filaments, namely PI-H (high strength and modulus), PI-M (moderate strength and modulus) and PI-L (low strength and modulus) filaments. The tensile strength of the PI-H, PI-M and PI-L filaments is 3.41, 1.65 and 0.88 GPa, and the Young’s modulus is 92.94, 40.71 and 9.43 GPa, respectively. The chemical compositions and structures of various PI filaments were characterized to explain the mechanical performance differences. The results show that the imidization degree, structural crystallinity and orientation have significant effects on the mechanical behaviors of PI monofilaments. The filament forces during the knitting process are simplified into straight tensile, loop tensile and abrasion actions, which have been tested and analyzed on PI monofilaments. A home-made simulative knittability analyzer was designed to test the knittability of the PI filaments. A hand flat knitting machine was used to verify the validity of the simulating methods and the constructed knittability analyzer. The PI-H, PI-M and PI-L filaments have poor, moderate and excellent knittability, respectively. The results also demonstrate that the simulating methods and the constructed simulative knittability analyzer are reasonable and efficient to evaluate the knittability of PI filaments.

A WC-reinforced composite coating was fabricated on the surface of 45 steel samples by plasma, cladding process with WC powder added to the molten pool synchronously or in the tail of the molten pool. The microstructure, phase composition, and element distribution in the coating were analyzed. The results show that the undissolved WC particles and crystallized carbide (WC, W2C) were distributed uniformly in the sub-eutectic matrix in both cases. Fewer of the WC particles are dissolved in the matrix when they are injected into the tail of the molten pool. There are fewer needle-like tungsten carbide formations seen in the composite coating fabricated by back-feeding process than in that formed by synchronous feeding. The former results in a finer microstructure and a higher concentration gradient of elements near the interface between the WC particles and the coating matrix.

When a patient takes two or more drugs within a certain time, the efficacy of one drug may be influenced by the other. This phenomenon is called drug-drug interactions (DDIs). DDIs are important and helpful information for both medical staff and patients to make sure that the drugs co-administrated at the same time have a positive effect on therapy of patients. Many approaches have been applied into drug-drug interaction extraction tasks such as support vector machine (SVM), recurrent neural network (RNN) and long short-term memory (LSTM) in particular. However, the structures of these models are relatively shallow for DDI extraction research compared with the deep neural networks employed in the field of computer vision. However much better results can be obtained with a deep problem-specific architecture which develops hierarchical representations. Hierarchical and deep neural networks may improve DDI extraction. To address this problem, we present a hierarchical and deep neural network to enrich the feature extraction process to enhance the performance of DDI extraction. In this article, we present a deep convolutional neural network (DCNN) based on DDI extraction method. In this method, we firstly apply embedding mechanism to get the semantic and syntactic of the original biomedical literature. Then a novel architecture using small convolutions is proposed, which takes raw biomedical literature as input and operates directly at the word level to get the embedding-based convolutional features. Finally, these features are fed to softmax classifier to extract DDIs from biomedical literature. Our experimental results on the DDIExtraction 2013 corpus show that the performance of network increases as the network gets deeper and hits its peak at depth 16, which obtains a better result (an F1 score $\mathrm {o}\mathrm {f}0.845$) than other state-of-the-art methods.

Primary particles formed in as-cast Al-5Mg-0.6Sc alloy and their role in microstructure and mechanical properties of the alloy were investigated using optical microscopy (OM), scanning electron microscopy (SEM), electron back-scatter diffraction (EBSD) and tensile testing. It was found that primary particles due to a close orientation to matrix could serve as the potent heterogeneous nucleation sites for α-Al during solidification and thus impose a remarkable grain refinement effect. Eutectic structure consisted of layer by layer of ‘Al 3 Sc + α-Al + Al 3 Sc + ⋯’ and cellular-dendritic substructure were simultaneously observed at the particles inside, indicating that these particles could be identified as the eutectics rather than individual Al 3 Sc phase. A calculating method, based on EBSD results, was introduced for the spatial distribution of these particles in matrix. The results showed that these eutectic particles randomly distributed in matrix. In addition, the formation of primary eutectic particles significant improved the strength of the Al-Mg alloy in as-cast condition, which is ascribed to the structural evolution from coarse dendrites to prefect fine equiaxed grains. On the other hand, these large-sized particles due to the tendency to act as the microcrack sources could cause a harmful effect in the ductility of Al-Mg-Sc alloy.

An addition of a high level of 0.6 wt% Sc imposed a remarkable grain refining effect on Al-5Mg alloy for as-cast condition, changing typical dendritic microstructure into fine equiaxed grains. Such effect was found to be related to the extensively formed Sc-rich particles. Electron back-scatter diffraction (EBSD), Atomic force microscopy (AFM) and SEM-elemental mapping were employed to investigate the inner structure of these particles and their role in grain refining. They could be identified as some eutectic structure consist of multilayer of ‘Al 3 Sc + α-Al+Al 3 Sc····’, which shows good consistency in orientation both in the particle and matrix.

The effect of Sc addition on microstructure and mechanical properties of as-cast Al–Mg alloys was investigated based on optical microscopy (OM), scanning electron microscopy (SEM), electron back-scatter diffraction (EBSD) and properties testing. The results showed that a remarkable grain refining effect was observed for Sc content greater than 0.4 wt.%, changing typical dendritic microstructure into fine equiaxed grains. Such effect was found to be related to the formed primary particles, which hindered the undesirable diffusion and subsequent crystal growth and acted as potent heterogeneous nucleation sites for α-Al matrix during solidification. In addition, these particles could cause a significant refinement strengthening effect. Atomic force microscopy (AFM) and SEM-elemental mapping were employed to investigate the internal structure and elemental distribution of these particles. They could be identified as the eutectics consisted of Al3Sc and α-Al phases rather than individual Al3Sc phase, which exhibited an ‘Al3Sc + α-Al + Al3Sc⋯’ multilayer structure. Keywords: Al–Mg–Sc alloys, Grain refinement, Eutectics, Multilayer structure

Polyimide (PI) is one of the lightweight and high-performance materials, having great potential to be used as reinforcements for advanced composites. Quantitative evaluation of fiber/matrix interface is critical in designing fiber reinforced polymer composites. However, there is a lack of effect characterization methods to measure the interfacial shear strength (IFSS) of polyimide fiber (PIF) due to its high failure strain. In this study, a modified single fiber fragmentation test (SFFT) was proposed to solve this problem. By employing Polyurethane (PU) resin as an additive in commercial epoxy resin, a transparent PU modified epoxy (PU-epoxy) resin is obtained. The PU-epoxy has a failure strain of 137.93%, which is much larger than 14.83% of the PIF, meeting the pre-requirement of SFFT. Oxygen plasma treatment is applied to modify surface properties of the PIF to improve its interfacial adhesion with epoxy. Statistical results show that a plasma-treated PIF for 4 mins achieves a 125.41% increase in IFSS compared with the pristine PIF. Meanwhile, a finite element model (FEM) is created to simulate and visualize stress distribution in fiber, interface, and matrix during the SFFT.

On the basis of space vector modulation and direct torque control, the double six-phase transverse flux permanent magnet motor is taken as the research object. The eighteen-sector stator-flux subdivision method is proposed to reduce current harmonics and improve the characteristic of direct torque control. Control strategy of duty ratio is improved to decrease the torque ripple made by voltage vector mutation. The algorithm combination of the eighteen-sector stator-flux subdivision method and the improved duty ratio algorithm is built as the core of space-vector modulation direct-torque control. The static and dynamic characteristics of control system are simulated. The results show that the new control system can effectively improve the circular flux curve, stable rotate speed, suppress the torque ripple, and enhance the output characteristics of motor torque and rotate speed.

In the present study, the effects of Mg, Cu, Sc and Zr combined additions on the microstructure and mechanical properties of hypoeutectic Al–Si cast alloy were systematically investigated. Characterization techniques such as optical microscopy (OM), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), electron back-scatter diffraction (EBSD), atomic force microscopy (AFM), transmission electron microscope (TEM), Brinell hardness tester and universal testing machine were employed to analyze the microstructure and mechanical properties. The results showed that Sc served as modifier on the microstructure of Al–3Si–0.45Mg–0.45Cu–0.2Zr alloys, including modification of eutectic Si and grains. Extraordinarily, grain refinement was found to be related to the primary particles, which exhibited a close orientation to matrix. After T6 heat treatment, the grain structures were composed of nano-scaled secondary Al3(Sc, Zr) precipitates and spherical eutectic Si. Combined with T6 heat treatment, the highest hardness, yield strength, ultimate tensile strength and elongation were achieved in 0.56 wt.% Sc-modified alloy. Interestingly, the strength and ductility had a similar tendency. This paper demonstrated that combined additions of Mg, Cu, Sc and Zr could significantly improve the microstructure and performance of the hypoeutectic Al–Si cast alloy.

The space robotic system is expected to perform the on orbit servicing mission. It is a challenging task to estimate the pose of the non-cooperative spacecraft (no facilities are mounted onboard for relative pose measurement) during the phase of closing, capturing, and maintenance. In addition, the spacecraft with a high value is always very large, which pose difficulties for the cameras to photo the whole scene in close range. This paper propose a new approach using combined vision system to estimate the relative position and attitude of a large non-cooperative spacecraft in close range. Based on investigation of the characteristics of spacecraft, a series of the feature point is selected as the recognized object. Then, rendezvous camera and eye-in-hand camera share the recognition task in a collaborative behavior, i.e. each traces one or two feature points on the target. In order to fuse the information, an extended PnP model is established. Lastly, the pose estimation algorithm by solving the extended PnP problem is addressed. Results of computer simulation validate the proposed approach.

The assimilation properties of iron ores are important during sintering. The amount of formed calcium ferrite was firstly used to evaluate the assimilation. Then, temperature and time of assimilation were proposed rather than the former one, which simplify the process and improve the operahility of experiments. However, the factors affecting the temperature were always neglected and using several indexes to evaluate the assimilation was inconvenient. In this paper, the assimilation reaction characteristic number taking the actual sintering temperature as the reference temperature was put forward to evaluate the assimilation of iron ores. This assimilation reaction characteristic number was a dimensionless number including kinds of important information during the assimilation reaction process. Results showed that the assimilation characteristic number can reflect the overall process of assimilation reaction between ores and CaO, which could help further analyze the assimilation difference of ores.