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With the rapid increase of the amount of vehicles in urban areas, the pollution of vehicle emissions is becoming more and more serious. Precise prediction of the spatiotemporal evolution of urban traffic emissions plays a great role in urban planning and policy making. Most existing methods usually focus on estimating vehicle emissions at historical or current moments which cannot well meet the demands of future planning. Recent work has started to pay attention to the evolution of vehicle emissions at future moments using multiple attributes related to emissions, however, they are not effective and efficient enough in the combination and utilization of different inputs. To address this issue, we propose a joint framework to predict the future evolution of vehicle emissions based on the GPS trajectories of taxis with a multi-channel spatiotemporal network and the motor vehicle emission simulator (MOVES) model. Specifically, we first estimate the spatial distribution matrices with GPS trajectories through map-matching algorithms. These matrices can reflect the attributes related to the traffic status of road networks such as volume, speed and acceleration. Then, our multi-channel spatiotemporal network is used to efficiently combine three key attributes (volume, speed and acceleration) through the feature sharing mechanism and generate a precise prediction of them in the future period. Finally, we adopt an MOVES model to estimate vehicle emissions by integrating several traffic factors including the predicted traffic states, road networks and the statistical information of urban vehicles. We evaluate our model on the Xi’an taxi GPS trajectories dataset. Experiments show that our proposed network can effectively predict the temporal evolution of vehicle emissions.

Combustion of agricultural residues for heat and electricity production is an efficient way to reduce amount of such waste source and emissions due to inappropriate treatment of them. However, unlike other biomass materials, agricultural residues often have high content of ash and certain ash forming elements with low meting temperatures, resulting in sintering and slagging during combustion processes. It complicates combustion of agricultural residues and restricts further utilization of this renewable energy source. In this work, sintering of a typical agricultural biomass cornstalk and effect of two phosphate additives, Ca(H2PO4)2·H2O and NH4H2PO4, were investigated by a combination of various techniques. Results indicated that the addition of Ca(H2PO4)2·H2O increased the initial melting temperature of cornstalk ash by 64–209 °C. The ash sintering behavior was greatly improved as a result of formation of high melting temperature K–Ca phosphates, Ca9MgK(PO4)7 and Ca2KP3O10 upon addition of the Ca(H2PO4)2·H2O. It is accompanied with reduced generation of low melting temperature K-rich silicates and the formation of large ash aggregates. Addition of NH4H2PO4 increased the initial ash melting temperature by 28–116 °C, but it had slight influence on the cornstalk ash sintering characteristics. The analysis revealed that, although the addition of NH4H2PO4 resulted in the formation of high melting temperature K2CaP2O7, certain amount of K phosphates and silicates eutectics were still formed, initiating and promoting sintering of ash from mixture of cornstalk and NH4H2PO4. Reactions between Ca(H2PO4)2·H2O and potassium salts under different conditions were also studied. It was found that reactions between Ca(H2PO4)2·H2O and potassium salts might already start as the temperature higher than 300 °C. K2CaP2O7, Ca2P2O7, Ca(PO3)2 and KCa(PO3)3 were identified as main products from these reactions and amounts of them considerably depends on the heat treatment temperatures and mixing ratios between Ca(H2PO4)2·H2O and potassium salts. Compared to KCl, K2CO3 had a higher reactivity toward the Ca(H2PO4)2·H2O under same study conditions. The current work shows the addition of Ca(H2PO4)2·H2O is a promising approach to alleviate the ash sintering issues and assure efficient and smooth combustion of cornstalk.

Engineering lattice defects in two-dimensional (2D) sulfide semiconductors has been accepted as an effective strategy to enhance the efficiency of the solar-to-fuels conversion. Although many researches have proven the lattice defect-mediated photocatalytic activity of ZnIn2S4, the artificial control of S-defects for optimizing the charge-carrier kinetics process in ZnIn2S4 has long been a challenging task. Herein, we report a facile one-step method to modulate the lattice S-content of ZnIn2S4 microflowers (MFs) only through adjusting the used amount of S-precursor in the hydrothermal solution that contains the metal precursors with a fixed Zn/In stoichiometric ratio at 1:2. We also demonstrated that the S-vacancies at the In facets were the main type of lattice defects in the formed ZnIn2S4 MFs, which could enhance both the separation and migration processes of the photoinduced charge-carriers due to the existence of discrete defect energy-levels (DELs) and the reduced effective mass of electrons, as evidenced by the first-principles calculations and the electron spectra analyses. The ZnIn2S4 MFs with the optimal content of S-vacancy obtained by a hydrothermal treatment of the precursors with the Zn/In/S stoichiometric ratio of 1:2:8 possessed the long-lived photoinduced electron (~94.64 ns) for contributing to the photo-physical and -chemical processes. Thus, upon visible light irradiation, the H2-evolution rate of this sample reached ~ 2.40 mmol h−1 g−1 with an apparent quantum efficiency of ~ 0.16% at 420 nm even though only using 5 mg of photocatalysts without any cocatalysts.

The low-temperature coal tar contains a considerable number of oxygen-containing compounds, which results in poor quality. The catalytic hydrodeoxygenation of oxygen-containing compound to an added-value chemical compound is one of the most efficient methods to upgrade coal tar. In this study, density functional theory calculations are employed to assess and analyze in detail the hydrodeoxygenation of dibenzofuran, as a model compound of coal tar, on the Ni (1 1 1) surface. The obtained results indicate that dibenzofuran can be firstly hydrogenated to tetrahydrodibenzofuran and hexahydrodibenzofuran. The five-membered-ring opening reaction of tetrahydrodibenzofuran is more straightforward than that of hexahydrodibenzofuran (Ea = 0.71 eV vs. 1.66 eV). Then, both pathways generate an intermediate 2-cyclohexylphenoxy compound. One part of 2-cyclohexylphenoxy is hydrogenated to 2-cyclohexylphenol and consecutively hydrogenated to cyclohexylcyclohexanol, and another part is directly hydrogenated to cyclohexylcyclohexanone. The hydrogenated intermediates of 2-cyclohexylphenol have higher deoxygenation barriers than 2-cyclohexylphenol and cyclohexylcyclohexanol. During the hydrogenation process of cyclohexylcyclohexanone to cyclohexylcyclohexanol, the intermediate 26, formed by adding H to O atom of cyclohexylcyclohexanone, exhibits the lowest deoxygenation barrier of 1.08 eV. High hydrogen coverage may promote the hydrogenation of tetrahydrodibenzofuran, hexahydrodibenzofuran, and intermediate 26 to generate dodecahydrodibenzofuran and cyclohexylcyclohexanol. This dibenzofuran hydrodeoxygenation reaction mechanism corroborates well with previous experimental results and provides a theoretical basis for further optimization of the design of nickel-based catalysts.

Current-induced spin-orbit torques (SOTs) are of interest for fast and energy-efficient manipulation of magnetic order in spintronic devices. To be deterministic, however, switching of perpendicularly magnetized materials by SOT requires a mechanism for in-plane symmetry breaking. Existing methods to do so involve the application of an in-plane bias magnetic field, or incorporation of in-plane structural asymmetry in the device, both of which can be difficult to implement in practical applications. Here, we report bias-field-free SOT switching in a single perpendicular CoTb layer with an engineered vertical composition gradient. The vertical structural inversion asymmetry induces strong intrinsic SOTs and a gradient-driven Dzyaloshinskii–Moriya interaction (g-DMI), which breaks the in-plane symmetry during the switching process. Micromagnetic simulations are in agreement with experimental results, and elucidate the role of g-DMI in the deterministic switching processes. This bias-field-free switching scheme for perpendicular ferrimagnets with g-DMI provides a strategy for efficient and compact SOT device design., Switching of ferrimagnets by current-induced spin-orbit torque is promising for spintronics, due to their high-speed dynamics and small macroscopic magnetization. Switching of perpendicularly magnetized materials, however, requires a bias field for symmetry breaking. Here, Zheng et al demonstrate field-free current-induced switching of perpendicular ferrimagnets, using a compositional gradient-driven Dzyaloshinskii–Moriya interaction.

As an ideal reinforcing phase, nano-carbon has been widely used to improve the properties of composites. In this paper, Mo–Cu–Zr ternary composites were reinforced with various types and contents of nano-carbon to find the optimal composition and the microstructure and mechanical properties of the composites were systematically characterized and analyzed. The composites were fabricated via a powder metallurgy method to achieve high compactness and structural uniformity. The analysis results show that the increase of nano-carbon may cause a serious agglomeration and subsequent decrease of the composite compactness, while the synergetic effect of carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) can improve their dispersion. The 0.8C + 0.2G-MCZ3 composite showed the best comprehensive properties, which achieved a relative density, hardness and compressive strength of 99.7%, 343.6 HV and 953.5 MPa, respectively. Moreover, the component Zr mainly formed solid solution and compound particles with Cu or C through in-situ chemical reactions. It played an important role in solid solution strengthening and dispersion strengthening, and the in-situ synthesized ZrC nanoparticles on nano-carbon surfaces can pin interfaces and improve the effect of load transfer. The synergetic effects and multiple strengthening mechanisms result in the improvement of the microstructure and properties of the composites.

Biochar supported nickel (Ni/BC) has been widely studied as a cheap and easy-to-prepare catalyst with potential applications in tar reforming during the gasification of low-rank fuels, such as brown coal and biomass. However, the role and behaviors of inherent K species, especially their interactions with Ni particles and the biochar support, are not well understood yet. In this work, three Ni/BC catalysts with varying K amount were prepared from raw, water-washed, and acid-washed biomass. They were used in steam reforming of toluene as a tar model compound to elucidate the effects of inherent K on the catalytic activity and stability. Detailed characterization indicated that K enhanced water adsorption due to its hydroscopicity and lowered the condensation and graphitization degrees of biochar, but the alteration to the electronic state of Ni was not observed. These effects together led to a temperature-dependent role of K. That is, at relatively low temperatures of 450 and 500 °C, toluene conversion was increased in the presence of K, due to the increased concentration of adsorbed water around Ni particles. By contrast, at relatively higher temperatures of 550 and 600 °C, although initial high activity was achieved, Ni/BC with K deactivated rapidly because of the accelerated consumption of the biochar support.

Low rank coal- and biomass-derived liquids generally contain a mixture of alkylphenols, which can be dealkylated over zeolites into phenol as a basic chemical. Zeolites with different pore structures were evaluated for the dealkylation of 4-iso-propylphenol as a model alkylphenol, among which HZSM-5 and HMCM-22 displayed the highest phenol selectivity above 96 %. However, HZSM-5 deactivated fastest among the catalysts due to coke deposition. Thus, mesopores were introduced by desilication into HZSM-5 catalysts to improve the catalytic stability. The mesopore incorporation enhanced the connectivity of the micropores with the crystal surface, and shortened the diffusion lengths. Coke location analysis revealed that micropore occlusion by the coke shell occurred on the parent HZSM-5, whereas the acid sites in the desilicated catalysts were more accessible for fully utilization, even though the coke mainly deposited in the micropores. Furthermore, the coke on the desilicated HZSM-5 displayed a lower graphitization degree.

High-emitting vehicles cause disproportionate air pollutants, thus making the identification and control of high-emitters a critical issue to reduce air pollution. On-road emission remote sensing (OERS), which can measure the emission of passing vehicles without interfering the normal driving, is an ideal means to identify the on-road high-emitting vehicles. Since the remote sensing measurements only reflect the instantaneous emission status, there is no doubt that OERS-output pollutant concentrations are related to the operation conditions and ambient environments at the measuring moment. Therefore, in order to identify on-road high-emitters effectively and accurately, a high-emitter identification model considering the relationship between OERS-output pollutant concentrations and their influence factors (such as passing speed, passing acceleration, wind speed, wind direction, temperature, etc.) should be established. In this paper, the way to establish the high-emitter identification model by machine learning is investigated. Because of the imbalanced distribution characteristic of emitter dataset, the weighted extreme learning machine is adopted as the identification model. Meanwhile, to enable an efficient establishment of the identification model, the active sampling that considers the dataset imbalance is introduced to select valuable samples to be labeled. The experimental results show that the high-emitter identification model establishment method based on weighted extreme learning machine can reduce the identification error for high-emitters significantly. Additionally, the active sampling can select valuable samples and improve the identification performance through the model update.

Membranes with high permeance and high rejection for di- and multivalent cation removal are highly desired for efficient brackish water and industrial water treatment. In this work, we report a facile strategy for constructing ultrathin nanofiltration (NF) membranes by in situ cross-linking of amine which is confined in a network film. The network made of single-walled carbon nanotubes (SWCNTs) serves as a framework for poly(ethylene imine) (PEI) to attach and stay, facilitating the formation of a polyamine (PA) layer with high quality and controlled thickness. Benefiting from the ultrathin thickness of the SWCNT network (∼31 nm), an active layer (∼34 nm thick) comes with a high permeance of 27 L m

All the supervised classification methods need sufficient and efficient samples, which are commonly labeled by visual inspection. In this study, to resolve the issues of insufficient training sampl...

Raman optical activity (ROA) is effective for studying the conformational structure and behavior of chiral molecules in aqueous solutions and is advantageous over X-ray crystallography and nuclear magnetic resonance spectroscopy in sample preparation and cost performance. However, ROA signals are inherently minuscule; 3–5 orders of magnitude weaker than spontaneous Raman scattering due to the weak chiral light–matter interaction. Localized surface plasmon resonance on metallic nanoparticles has been employed to enhance ROA signals, but suffers from detrimental spectral artifacts due to its photothermal heat generation and inability to efficiently transfer and enhance optical chirality from the far field to the near field. Here we demonstrate all-dielectric chiral-field-enhanced ROA by devising a silicon nanodisk array and exploiting its dark mode to overcome these limitations. Specifically, we use it with pairs of chemical and biological enantiomers to show >100x enhanced chiral light–molecule interaction with negligible artifacts for ROA measurements., Raman optical activity (ROA) is useful for studying conformational structure and behavior of chiral molecules, but is limited by the weak signals. Here, the authors demonstrate 100x signal enhancement via an all-dielectric approach, using a silicon nanodisk array and exploiting its dark mode.

The morphing trailing edge based compliant mechanism is a developing technology which can increase lift-drag ratio for variable flight modes by bending down the trailing edge. Composite material design is integrated into topology optimization for the morphing trailing edge based compliant mechanism in the paper. A two-step optimization strategy is established to solve the integrated design problem. Initially, lamination parameters are introduced and viewed as a bridge between structure stiffness and fiber angles for composite material. Design variables include the lamination parameters and element density. The least-squares between actual and desired displacements at output points along trailing edge is adopted to evaluate the deformed capability of the trailing edge. An integrated optimization model for the composite morphing trailing edge is established with the volume constraints. The optimal topologic shape and lamination parameters are initially obtained. Subsequently, a least-squares optimization between fiber angles and the optimal lamination parameters is implemented to obtain optimal fiber angles. Finally, morphing capability of composites trailing edge based compliant mechanism is investigated by simulation and experiments. The results indicate the composites trailing edge based compliant mechanism can approximately bend down 8 degrees and satisfies the design requirement.

One of the severe plastic deformation techniques, elliptical cross-sectioned spiral equal-channel extrusion (ECSEE) was successfully applied to the pure Mg processed at 200°C and the microstructure...

A low defect density in metal halide perovskite single crystals is critical to achieve high performance optoelectronic devices. Here we show the reduction of defect density in perovskite single crystals grown by a ligand-assisted solution process with 3‐(decyldimethylammonio)‐propane‐sulfonate inner salt (DPSI) as an additive. DPSI ligands anchoring with lead ions on perovskite crystal surfaces not only suppress nucleation in solution, but also regulate the addition of proper ions to the growing surface, which greatly enhances the crystal quality. The grown CH3NH3PbI3 crystals show better crystallinity and a 23-fold smaller trap density of 7 × 1010 cm−3 than the optimized control crystals. The enhanced material properties result in significantly suppressed ion migration and superior X-ray detection sensitivity of CH3NH3PbI3 detectors of (2.6 ± 0.4) × 106 µC Gy−1air cm−2 for 60 kVp X-ray and the lowest detectable dose rate reaches (5.0 ± 0.7) nGy s−1, which enables reduced radiation dose to patients in medical X-ray diagnostics., The performance of a metal halide perovskite single crystal is governed by the defect density. Here, the authors report a high quality single crystal perovskite grown by a ligand-assisted solution process with DPSI achieving 23-fold smaller trap density than that without DPSI.

Transition-metal aluminium nitrides widely used as protective tool coatings are a class of materials with a combination of high hardness, outstanding wear resistance as well as good chemical stability. In this work, through a well developed structure searching method, the ground-state phase of V0.5Al0.5N is verified and systematically studied on its mechanical and electronic properties by comparing with Ti0.5Al0.5N and W0.5Al0.5N via first-principles calculations. Our results show that the ground-state phase of V0.5Al0.5N adopts a hexagonal structure of P63/mmc symmetry. Mechanical property studies demonstrate the hexagonal phase has a surprisingly improved hardness of about 38 GPa and enhanced ideal strengths relative to its well-known metastable cubic B1 phase whose hardness is only about 20 GPa. This mechanical enhancement greatly expands the upper limit of the strength and hardness for this type of Al-containing ternary systems. Meanwhile, detailed analysis on strength and elastic anisotropy indicates it also exhibits much better mechanical isotropy. Underlying mechanism of the mechanical enhancement is explored by the electronic analysis in-depth. The position of the EF is tuned by the introduction of the Al element and this electronic tuning leads to a metallic-to-semiconductor transformation from B1 to the hexagonal phase and the strengthening of the bonds between the metal elements and the N atoms.

Catalytic hydrodeoxygenation is an efficient method to upgrade the quality of low-temperature coal tar and coal liquefied oil. However, only limited researches are performed on the mechanism of hydrodeoxygenation and, therefore, innovation of more efficient and stable catalysts is less progressed and still remains a challenging subject. In this study, density functional theory calculations are carried out to get a deeper insight in the mechanism of dibenzofuran hydrodeoxygenation on the Pt(111) surface. Calculated energies and activation barriers indicate that five-membered-ring opening of tetrahydrodibenzofuran is easier than that of hexahydrodibenzofuran. Then, the generated intermediate can be preferentially hydrogenated through a non-consecutive pathway to 2-cyclohexylphenol, and would result in multiple radical species. The dehydroxylation of that intermediate formed by adding five hydrogen atoms to the phenyl ring of 2-cyclohexylphenol shows a moderate reaction barrier of 1.07 eV; whereas, dehydroxylation of cyclohexylcyclohexanol needs a higher energy barrier of 2.04 eV. For the hydrodeoxygenation of dibenzofuran on the Pt(111) surface, the target product bicyclohexane is most likely to be formed through a radical intermediate. This investigation may provide a potent theoretical guidance to design new catalyst for hydrodeoxygenation of coal to liquid.

The data transfer bottleneck in Von Neumann architecture owing to the separation between processor and memory hinders the development of high-performance computing. The computing in memory (CIM) concept is widely considered as a promising solution for overcoming this issue. In this article, we present a time-domain CIM (TD-CIM) scheme using spintronics, which can be applied to construct the energy-efficient convolutional neural network (CNN). Basic Boolean logic operations are implemented through recording the bit-line output at different moments. A multi-addend addition mechanism is then introduced based on the TD-CIM circuit, which can eliminate the cascaded full adders. To further optimize the compatibility of TD-CIM circuit for CNN, we also propose a quantization method that transforms floating-point parameters of pre-trained CNN models into fixed-point parameters. Finally, we build a TD-CIM architecture integrating with a highly reconfigurable array of field-free spin-orbit torque magnetic random access memory (SOT-MRAM) and evaluate its benefits for the quantized CNN. By performing digit recognition with the MNIST dataset, we find that the delay and energy are respectively reduced by 1.2-2.7 times and $2.4\times 10 ^{3} - 1.1\times 10 ^{4}$ times compared with STT-CIM and CRAM based on spintronic memory. Finally, the recognition accuracy can reach 98.65% and 91.11% on MNIST and CIFAR-10, respectively.

Coal seam water injection, as an indispensable process in underground mining, is of great significance to the treatment of dust hazard in working face. However, the permeability of water in the coal seam is unsatisfactory due to hydrophobic properties of coal and many other factors. Here we synthesized a water injection additive with stellate structure by modified β-cyclodextrin. The molecular structure characteristics of the product were analyzed by FTIR, XRD and TG-DTG-DSC. The permeability and wettability of materials, which are closely related to water injection were tested. The contact angle of 0.1% product solution was only 25°. Moreover, combined with the characteristics of molecular structure and the effects, the principle of action was explained. And the optimum reaction conditions were determined. After performance testing, the synthesized material has stronger penetrating and pre-wetting ability than common surfactants, and the mechanism of its action was explained based on the molecular characteristics of the material.

Aiming at the “light wind start, light wind power generation” of vertical axis wind turbine, a new T-shaped radial passive magnetic bearing with high suspension characteristics is proposed. Passive magnetic bearings used in vertical axis wind turbines usually have small bearing capacity and difficult magnetization. The new T-shaped radial PMB can improve the radial bearing capacity, and the three magnetic rings all adopt simple axial magnetization. The new T-shaped radial PMB is combined with mechanical auxiliary bearing to form the suspension system of wind turbine. In the stable state, the suspension system can realize radial and axial stable suspension. The structure and working principle of the suspension system are briefly described. Through the finite element simulation, the characteristics of the new T-shaped radial PMB, the traditional double-ring PMB and the T-shaped PMBs are compared. Taking the high bearing capacity and high stiffness of the new T-shaped radial PMB as the optimization objective, the multi-objective optimization of the new T-shaped radial PMB was carried out by changing its geometric parameters (inner diameter, magnetization length and air gap). The research results show that: Under the same bearing capacity, the volume of the new T-shaped radial PMB is reduced by about 78.64%. Under the same volume, its bearing capacity increased by about 30.7%, and its stiffness increased by about 96.1%. After optimization, its radial bearing capacity increased to 101.38 N, and its stiffness increased to 202.76 N/mm.

In recent years, high-performance half-Heusler compounds have been developed as promising thermoelectric materials for power generation. Aiming at practical device applications, one key step is to seek suitable metal electrodes so that low interfacial resistivity is guaranteed under long-term thermal aging. In the previous work, the fresh Mo/Nb

Our theoretical research indicate that the electric field are generated in the direction of (C doped) TiO2 (101) surface to (B-doped) g-C3N4 monolayer for the pristine, C and B doped g-C3N4/TiO2, and higher band-edge potential on the (C doped) TiO2 (101) surface are observed compared to (B-doped) g-C3N4 monolayer. Thus, the pristine (2.591 eV), C-doped (2.663 eV) and B-doped (2.339 eV) g-C3N4/TiO2 are Z-scheme heterostructures, which promotes charge separation and retains a prominent redox ability. After C doping, the C 2p energy level is introduced which facilitate the separation of photoexcited carriers. The B-doped g-C3N4/TiO2 has a reduced bandgap and the mixing of B 2p and N 2p energy levels, promoting the red-shift of the optical absorption edge. The C&B codoped g-C3N4/TiO2 follows type-II charge transfer mode because of their synergistic effect in C and B atoms, which changes the direction of the built-in electric field. It also has a narrow bandgap (1.309 eV) and effectively separate electron-hole pairs leading to strong optical absorption ability in the range of 360 nm–460 nm. The band-edges matching of the semiconductor photocatalyst and the direction of the built-in electric field jointly determine whether the charges are selected to be Z-scheme or II-type transfer mode. Based on g-C3N4/TiO2 for C or/and B (co)doping, their different charge transfer modes have been established and they are expected to show promising photocatalytic water splitting performance.

How to efficiently tag the emotional experience of multimedia contents is an important and challenging problem in the field of affective computing. This paper presents an EEG-based real-time emotion tagging approach, by extracting inter-brain features from a group of participants when they watch the same emotional video clips. First, the continuous subjective reports on both the arousal and valence dimensions of emotion were obtained by employing a three-round behavioral rating paradigm. Second, the inter-brain features were systematically explored in both spectral and temporal domain. Finally, regression analyses were performed to evaluate the effectiveness of inter-brain amplitude and phase features. The inter-brain amplitude feature showed significantly better prediction performance than the inter-brain phase feature, as well as another two conventional features (spectral power and inter-subject correlation). By combining the four types of features, regression values (R2) were obtained for the prediction of arousal ( ${{0.61}}\pm {{0.01}}$ 0 . 61 ± 0 . 01 ) and valence ( ${{0.70}}\pm {{0.01}}$ 0 . 70 ± 0 . 01 ), corresponding to prediction errors of ${{1.01}}\pm {{0.02}}$ 1 . 01 ± 0 . 02 and ${{0.78}}\pm {{0.02}}$ 0 . 78 ± 0 . 02 (unit on 9-point scales), respectively. The contributions of different electrodes and frequency bands were also analyzed. Our results show promising potentials of inter-brain EEG features in real-time emotion tagging applications.

Metal–organic framework (MOF) materials have been extensively incorporated with inorganic semiconductor photocatalysts to improve their photocatalytic activity through an efficient charge transfer process across their heterointerface. In this work, octahedral UiO-66-NH2 MOFs with edge-lengths of 110–330 nm are uniformly decorated on the surface of TiO2 electrospun nanofibers by a traditional solvothermal method combined with activation pretreatment. Before the solvothermal growth of UiO-66-NH2, the TiO2 electrospun nanofibers were activated in NaOH solution to etch the TiO2 surface for allowing the exposure of lattice oxygen. The exposed lattice oxygen on the TiO2 surface could interact with the MOF precursor of Zr4+ ions, thus enabling octahedral UiO-66-NH2 to grow uniformly on the surface of TiO2 nanofibers with an intimate Ti–O–Zr hetero-interface. Such an intimate hetero-interface provides an effective channel for boosting the electron transfer between UiO-66-NH2 and TiO2 in their heterostructure. Thus, the UiO-66-NH2/TiO2(anatase) heterostructures exhibited enhanced photocatalytic activity for H2 production as compared to either TiO2(anatase) nanofibers or UiO-66-NH2 nanooctahedra in the presence of Rhodamine B (RhB) as a sensitizer under visible light irradiation. In particular, the decoration of UiO-66-NH2 nanooctahedra on anatase/rutile mixed TiO2 nanofibers could induce further enhancement of the photocatalytic H2 production. The enhanced photocatalytic activity is attributed to the multi-step continuous interfacial transfer of photoinduced electrons with the way of RhB → UiO-66-NH2 → TiO2(anatase) → TiO2(rutile).

A systematic theoretical research on the geometrical, electronic, optical, charge transfer, and photocatalytic mechanisms of pure, Cr-doped, B-doped, and (Cr, B) codoped g-C3N4/BiVO4 heterostructures using a hybrid density functional approach has been carried out. The face-to-face g-C3N4/BiVO4 composed of two-dimensional materials of g-C3N4 and BiVO4 (010) surface, can introduce a built-in electric field, which promotes interface charge transfer and prevents the electron-hole pair recombination, and causing g-C3N4 monolayer with negative charge and BiVO4 (010) surface with positive charge. Under visible light irradiation, electrons are excited to the conduction band minimum (CBM) of the BiVO4 (010) surface undergoing the hydrogen evolution reaction (HER), while the holes remain in the valence band maximum (VBM) of g-C3N4 monolayer aiding the oxygen evolution reaction (OER). The band edge potentials of BiVO4 (010) surface is higher than that of g-C3N4 monolayer, which ensures a stronger redox reaction potential and therefore belongs to a typical Z-scheme heterostructure. In addition, the Cr or/and B (co)doping introduces the Cr-3d or/and B-2p states to reduce the bandgap and generate impurity levels, thus enhancing solar energy utilization rate and expanding the optical absorption in the visible-light range. The optical absorption intensity of the (Cr, B) codoped g-C3N4/BiVO4 is superior to pure and Cr or B doped g-C3N4/BiVO4, confiriming the synergistic effect of Cr-3d and B-2p states. Thus, this research is helpful to design a novel and potential Z-scheme photocatalyst useful for the photocatalytic water splitting.

The data with the advancement of information technology are increasing on daily basis. The data mining technique has been applied to various fields. The complexity and execution time are the major factors viewed in existing data mining techniques. With the rapid development of database technology, many data storage increases, and data mining technology has become more and more important and expanded to various fields in recent years. Association rule mining is the most active research technique of data mining. Data mining technology is used for potentially useful information extraction and knowledge from big data sets. The results demonstrate that the precision ratio of the presented technique is high comparable to other existing techniques with the same recall rate, i.e., the R-tree algorithm. The proposed technique by the mining effectively controls the noise data, and the precision rate is also kept very high, which indicates the highest accuracy of the technique. This article makes a systematic and detailed analysis of data mining technology by using the Apriori algorithm.

The synchrosqueezing transform (SST) and its ameliorated methods can enhance the energy concentration of the vibration signals in time-frequency domain, but it does not show enough effect for the weak feature extraction. Besides, many large-scale rotating machines such as aerospace engines and gas engines often work under complex vibrations, and this increases the difficulty for health monitoring based on vibration signals. This article presents a time-frequency analysis (TFA) named bilateral second-order SST (BFSST2). It can sharpen the instantaneous frequencies (IFs) like second-order SST (FSST2), and more importantly, it can extract the weak features such as amplitude-modulation frequency-modulation IFs and small-amplitude time-varying IFs which are easily ignored on time-frequency plane. To achieve the aforementioned target, the IFs are first obtained by employing FSST2, and then a bilateral function representing a novel negative-positive TFA is structured by combining the hyperbolic tangent function, exponential function, and sign function together. After that the large-amplitude IFs are transformed into small-negative amplitude ones by the product with the bilateral function, and this can not only enhance the original weak feature but also avoid its confusion with the transformed small-negative amplitude ones. The proposed BFSST2 is validated by a numerical simulation. At last, two case studies are given to illustrate its effectiveness in aerospace engine vibration monitoring.

Porous polymeric support membranes with outstanding organic solvent resistance are highly required for fabricating thin-film composite (TFC) organic solvent nanofiltration (OSN) membranes. In this ...

Summary The presence of a defective layer composed of nanocrystals and amorphous regions at the surface of perovskite films has been shown to initialize the degradation of perovskites and cause nonradiative recombination. Here, we report the discovery that these defective surface layers are mechanically softer than the crystalline regions. The defective surface layer has a weaker bonding with the crystalline layer underneath it, which enables a facile approach to mechanically peel-off these defective layers using adhesive tapes. The chosen low-cost tape has an appropriate bonding force with perovskites, so the peeling does not damage the crystalline region and embedded interfaces underneath. The tape-treated devices retained 97.1% of the initial efficiency after operation at the near maximum power point under one sun illumination for 1,440 h at 65°C. This method is universally effective in enhancing the stability of various commonly used perovskite compositions and is compatible with the scaling up of perovskite solar modules.

Covalent organic framework (COF)-based membranes are burgeoning candidates for separation technologies owing to their well-ordered channel structures. The exponential interest in the stability of the COF membrane on exposure to harsh organic solvents is directed to develop a composite membrane for dye separations in polar aprotic solvents. Here, we reported a nanocomposite membrane composing of a single-walled carbon nanotube (SWCNT)/COF (an imine-based COF) hybrid on a commercial polytetrafluoroethylene (PTFE) substrate, with a thickness of ∼58 nm prepared in a diffusion cell. This membrane displayed high permeability and stability toward nonpolar and aprotic solvents. It exhibited high permeability for lower viscous organic solvents such as hexane (66 L m

A self-embedding watermarking algorithm based on a reference sharing mechanism that has recovery ability under high tampering rates is proposed in this paper. In existing methods, the image recover...

Spark plasma sintering (SPS) is a powerful technique for consolidating metal powders at a remarkably shorter time with excellent quality. We used this technique for sintering nanocrystalline WC10Co powders and simultaneously bonding with high-strength steel. A series of experiments were conducted in order to find out the optimised set of SPS controlling parameters. The effects of temperatures (1000 to 1150 °C, with a 50 °C interval) in sintering nanocrystalline WC10Co powders and their bonding phenomena with AISI4340 steel were examined at a constant pressure of 80 MPa and a holding time of 5 min. The full density of the carbide powders was achieved at a lower temperature compared with that of conventional techniques. A number of techniques were employed to evaluate the microstructural characteristics of WC and steel bilayered composite and their mechanical properties. For determining the bonding strength of the joint, a novel micro-tensile testing system was adopted. Since such investigation is the first of its kind, to the best knowledge of the authors, where SPS is used to join the tungsten carbide with the steel, this research is expected to provide a valuable future reference for fabricating dissimilar bilayered composite materials.

Summary Controlling of doping in semiconducting light absorber can minimize the charge recombination and maximizing power output from solar cells; however, it is challenging for perovskites due to lack of controlled doping. Here, we report that a short post-annealing of less than 3 min for facilitating high-throughput manufacturing of perovskite solar modules in an ambient environment maintains the stoichiometric composition of perovskites, encouraging a spontaneous de-doping of perovskites during aging. The reduced self-doping results in less charge recombination and, thus, higher device efficiency. The stabilized open-circuit voltage of sub-cells in the CH3NH3PbI3 minimodules with an area >20 cm2 reaches 1.19 V on average. The aperture efficiency reaches 17.8% under one sun and 18.7% under a quarter sun illumination, deriving an averaged efficiency >20.0% for each sub-cell with an area >3 cm2, demonstrating the excellent uniformity of the films by this scalable process. The minimodule also works as uniform light-emitting devices.

An air curtain dust control technology for a fully mechanized mining face was developed, using a method that combined numerical simulations with field measurements in this paper. The results show that a triangular air curtain was formed between the shearer and the footway by the high velocity airflow field generated at the outlets of two fans after the technology was applied, which can effectively prevent dust from entering the driver's working area. Before the dust control technology was applied, the dust concentration of the shearer driver's working area exceeded 2000 mg/m3. However, after the dust control technology was applied, the dust concentration of the shearer driver's working area was reduced to 300 mg/m3. After verification through field measurements, the dust control rate of each measuring point, apart from the advancing support, exceeded 40%, and that of the shearer driver's working area was over 90%.

In this work, α-Al2O3 whisker reinforced Cu-graphite matrix composites were prepared by spark plasma sintering. Results show that the surface modification of α-Al2O3 whiskers with sodium dodecyl sulfate solution can improve its dispersibility, and the composites obtained are basically completely dense. The relative density of all composite materials is above 95%. The interface bonding mode in the composite is mainly mechanical bonding, and the formation of a diffusion layer is also observed from interfaces. With the increase of α-Al2O3 whisker content, mechanical properties of the composites increase first and then decrease. The composite with 1.0 wt% α-Al2O3 whisker has the best performance. The corresponding relative density, hardness and compressive strength are 96.35%, 56.20 HV, 139.12 MPa, respectively. By analyzing microstructure and fracture morphology of the composites, it is determined that the strengthening mechanisms are mainly fine grain strengthening, particle strengthening and load transfer. Simultaneously, the fracture type is brittle fracture., This work was supported by Key Laboratory of Infrared Imaging Materials and Detectors, Shanghai Institute of Technical Physics, Chinese Academy of Sciences (No.IIMDKFJJ-19-08) and China Postdoctoral Science Foundation (No. 2015M570794, No. 2018T110993).

The soft nature of metal halide perovskites makes them potentially applicable as flexible X-ray detectors. Here we report a structure of perovskite-filled membranes (PFMs) for highly sensitive, flexible and large-area X-ray detectors. PFMs with areas up to 400 cm2 are formed by infiltrating saturated perovskite solution through porous polymer membranes followed by hot lamination. The good connectivity and crystallization of perovskite crystals in the membranes enable a large mobility–lifetime product. The sensitivity of the X-ray detectors under a field of 0.05 V µm−1 reaches 8,696 ± 228 µC Gyair−1 cm−2 and shows no degradation after storage for over six months and exposure to a dose of 376.8 Gyair, equivalent to 1.88 million chest X-ray scans. The flexible PFMs can be bent at radii down to 2 mm without losing performance. The stand-alone detector array is curved and put inside metal pipes for the detection of material defects with imaging quality superior to flat-panel detectors. Perovskite-filled-membranes enable flexible, sensitive and large-area X-ray detectors. The structures are made by infiltrating perovskite solution into porous polymer membranes.

The efficiencies of all-perovskite tandem devices are improving quickly. However, their complex interconnection layer (ICL) structures—with typically four or more layers deposited by different processes—limit their prospects for applications. Here, we report an ICL in all-perovskite tandem cells consisting merely of a fullerene layer and a SnO2–x (0

© 2020, © 2020 Informa UK Limited, trading as Taylor & Francis Group. In this study we examined the effects of compaction pressure for bonding nanocrystalline cemented tungsten carbide (WC-10Co) and high-strength steel (AISI4340) and successfully fabricated a bilayered composite of ceramic and steel. The obtained results were compared with our previous studies, and then the optimised sintering conditions were suggested. The compaction pressure examined varied from 120–200 MPa at 1150°C for 20 min. The study shows that the change in experimental parameters has significant effects on both the sintering properties of nanocrystalline WC-10Co powders and their bonding with AISI4340 steel. The microstructure reveals a successful metallurgical bonding between ceramic and steel. Bonding temperature determines, to a great extent, the diffusion processes across the bonding interface and has found to be the most influential variable compared to sintering time and compaction pressure. The obtained average maximum bonding strength of the bimetal composite is 226 MPa, which is higher than that of previous studies.

In this study, nonequiatomic Co28.5Cr21.5Fe20Ni26Mo4 medium-entropy alloys (MEAs) were prepared using hot isostatic pressing. The effect of annealing heat treatment on microstructure and mechanical properties of MEAs was investigated. The results showed that the microstructure of as-sintered alloys was mainly composed of the face-centered cubic (FCC) phase and μ phase. The presence of the μ phase could improve the compressive strength of Co28.5Cr21.5Fe20Ni26Mo4 MEAs. Meanwhile, the ductile FCC phase matrix could effectively suppress the propagation of cracks to improve its ductility. Hence, as-sintered MEAs possessed excellent compression properties, and the average compressive strength value was 2,606 MPa when the strain was 50%. Compared with as-sintered MEAs, the phase composition of as-annealed MEAs did not change. The micro-hardness of annealed MEAs was stable compared to as-sintered MEAs (342 HV), and its fluctuation was about ±30 HV. The compressive strength of the annealed MEAs did not alter greatly, and the maximum fluctuation value was only about 6.5%. Hence, Co28.5Cr21.5Fe20Ni26Mo4 MEAs had excellent thermal stability.

Neural networks have been widely deployed in a number of applications due to their strong learning and feature extraction ability. To meet the ever increasing accuracy requirements from various applications, neural network models have become more complicated and diversified by exploiting more layers, larger model size, and more diverse functions. As a result, the design of application specified hardware accelerators for neural networks is also becoming more difficult, especially for real-time embedded applications. To efficiently bridge the gap between algorithm and hardware design phases, a pre-RTL neural network simulator (SimuNN) is proposed in this paper to enable early phase verification and fast prototyping. SimuNN can be used for inference, simulation and also evaluation, results of which can guide the design of both neural network models and hardware accelerators. SimuNN supports inference in various data precision, and is compatible with TensorFlow, which makes it easy for platform migration. It provides multi-level trace results that can be taken as the gold model of RTL designs. Moreover, the hardware performance under various quantizations, dataflow organizations and hardware configurations can be evaluated by SimuNN based on a generalized hardware model. Based on that, two dataflow organization schemes are concluded for determining the optimal configurations of hardware architecture under various hardware and performance constraints.

The enhancement of the breakdown power during the spark discharge process has been proved to be beneficial for the flame kernel formation process under lean/diluted conditions. Such a strategy is realized by using a conventional transistor coil ignition system with an add-on capacitance in parallel to the spark plug gap in this paper. In practical application, the use of different ceramic material other than aluminum oxide can change the parasitic capacitance of the spark plug, achieving similar effect in terms of rescheduling the discharge energy released during the breakdown phase. Detailed research has been carried out to investigate the effect of the parallel capacitance and the cross flow velocity on the flame kernel formation and propagation process. With the increase in parallel capacitance, more spark energy is delivered during the breakdown phase, while less energy is released during the arc/glow phase. Shadowgraph images of the spark plasma reveal that the high-power spark discharge can generate a larger high-temperature area with enhanced electrically prompted turbulence under quiescent conditions, as compared with that using the conventional transistor coil ignition discharge strategy under the same condition. The breakdown enhanced turbulence of the high-power spark is proved to be beneficial for the flame kernel development, especially with the lean or exhaust gas recirculation diluted combustible mixtures, given that sufficient spark energy is available for the high-power spark strategy to successfully generate the breakdown event. The results of combustion tests under flow conditions reveal that the breakdown enhanced turbulence of the high-power spark tends to be overshadowed by the turbulence generated from the flow field, and both the increase in flow velocity and parallel capacitance contribute to the reduction in discharge duration of the arc/glow phase. Therefore, the benefits brought about by the high-power spark discharge tend to diminish with the intensification of flow velocity.

The influences of combined torsion-tension deformation on the microstructural evolution and corrosion resistance of 316L stainless steel were investigated. The microstructure and corrosion behavior of the deformation samples were studied in detail. The results showed that the grains were more significantly refined under combined deformation than under tensile deformation. However, further increase in pre-torsion led to little change in grain size. The results of transmission electron microscopy and corrosion tests results indicated that high-density dislocations were detrimental, whereas the corrosion resistance, grain refinement and deformation twins were beneficial to corrosion resistance. Furthermore, the effect of deformation twins on corrosion resistance was greater than that of dislocation density, which, in turn, was greater than the influence of grain size.

Urban vehicle emission monitoring can help make suggestions for the pollution emission control, and can protect public health. However, it is hard to get an overview of the vehicle emission in the city scale due to the sparse emission remote sensing stations in city, and selecting the appropriate stations locations which can reflect the emission variation in the given region mostly is another challenge. The existing methods solve the problem by spatial interpolation based on geographical statistics methods, without considering that urban vehicle emission varies by locations non-linearly and depends on many complex external factors. To tackle the spatial sparsity of vehicle remote sensing data, we design a data augmentation strategy based on Generative Adversarial Networks (GAN), which leverages prior model COPERT with conditional measurement data to filling the missing entries at other locations. With this strategy, we can generate realistic emission data while accelerating the training process. In addition, to address the emission stations location selection problem, we design a novel location selection strategy based on Spearman’s rank correlation coefficients, which leverages the realistic data generated to discover the grids with maximum link correlation for the pre-deployed station. Finally, we present experiments with the remote emission sensing data in Hefei, and the results demonstrate that our proposed model can mimics the real vehicle emission distribution in the given region effectively.

To address the low gas sensitivity of pristine graphene (Gr), chemical modification of Gr has been proved as a promising route. However, the existing chemical functionalization method imposes the u...

Summary Integrating perovskites onto textured silicon provides a pathway to 30% tandem solar cells. However, deposition of 0.5–1 μm thick perovskite layers from solution onto textured silicon with typical pyramid heights of 3–10 μm remains a challenge. We propose a new tandem architecture that enables scalable, solution-based blading of perovskites onto silicon wafers textured with pyramids less than 1 μm in height. These pyramids are rough enough to scatter light within the silicon nearly as efficiently as large pyramids but smooth enough to solution-process a perovskite film. A nitrogen-assisted blading process deposits both a conformal hole transport layer and a planarizing perovskite layer that fully covers the textured silicon, at a speed of 1.5 m/min. With a textured light-scattering layer added to the top of the tandem to reduce front-surface reflectance, we achieve a perovskite/silicon tandem cell with an efficiency of 26% on textured silicon.

Separating molecules or ions with sub-Angstrom scale precision is important but technically challenging. Achieving such a precise separation using membranes requires Angstrom scale pores with a high level of pore size uniformity. Herein, we demonstrate that precise solute-solute separation can be achieved using polyamide membranes formed via surfactant-assembly regulated interfacial polymerization (SARIP). The dynamic, self-assembled network of surfactants facilitates faster and more homogeneous diffusion of amine monomers across the water/hexane interface during interfacial polymerization, thereby forming a polyamide active layer with more uniform sub-nanometre pores compared to those formed via conventional interfacial polymerization. The polyamide membrane formed by SARIP exhibits highly size-dependent sieving of solutes, yielding a step-wise transition from low rejection to near-perfect rejection over a solute size range smaller than half Angstrom. SARIP represents an approach for the scalable fabrication of ultra-selective membranes with uniform nanopores for precise separation of ions and small solutes., Separating molecules or ions with sub-Angstrom scale precision is important but technically challenging. Here, the authors demonstrate that precise solute-solute separation can be achieved using polyamide membranes formed via surfactant-assembly regulated interfacial polymerization.

To manage and control massive distributed energy resources (DERs) integrated into active distribution networks (ADNs), dispersed DERs are aggregated as virtual power plants (VPPs). This study introduces a distributed optimal dispatch strategy of VPPs considering operational constraints in unbalanced ADN. First, a practical multi-VPP coordination optimal dispatch model considering P–Q coupling characteristics in unbalanced ADN is proposed. Then, the primal–dual interior-point algorithm is employed to transform the original model into a Karush–Kuhn–Tucker equation, where afterwards distributed quasi-Newton method is developed to solve the equation. Under the proposed distributed strategy, each VPP only communicates limited boundary information with utility grid. With the advantage of quasi-second-order information, the proposed method outperforms the popular distributed gradient-based algorithm, alternating direction method of multipliers. The distributed method provides merits such as efficient calculation and privacy protection for multi-VPP operation in ADN. Numerical tests evaluate the efficiency and accuracy of the proposed method.

Alkaline metal borohydrides are extensively studied as promising candidates for hydrogen storage. They have similar chemical composition, but their ground-state structures exhibit regular changes. The larger the alkali cations, the higher the structural symmetry, the lower the phase transition temperatures. This phenomenon has been discussed extensively in the literature, and the determination and understanding of its origin also caused considerable controversy. In this work, through comparative analysis of the electronic structures, mechanical properties, dynamic properties and thermodynamic properties of a series of alkaline metal borohydrides, the origin of the structural diversity, under the Pauling classification, are revealed and attributed to the coordination numbers of the alkaline cations, and the thermally activated reorientation of the anionic groups. The ionic radii are defined in this work as the Bader partition radius based on the ground state electron densities in specific model structures. The coordination number is 4 for the central cation Liq+ (tetrahedral coordination in Pnma) and 6 for other alkali cations, as the cation-anion radius ratio of LiBH4 is about 0.32 while those of NaBH4, KBH4, RbBH4 and CsBH4 are 0.44, 0.58, 0.63 and 0.69, respectively, which greater than 0.414 and less than 0.732. B forms strong polar covalent bonds with 4 surrounding H, with hydrogen slightly negatively charged. It was found that both the repulsions between the adjacent anions and the attractions between the anions and the cations favor the observed trend. The joint effect of the repulsive and attractive forces on the anionic groups in NaBH4 and KBH4 results in the Face-to-Face form (as in P42/nmc). The calculated rotation barriers of [BH4]q− at the equilibrium configuration of each species indicates that, in general, the larger the cation radius, the lower the activation barrier is. These interactions attenuate quickly with the increase of the distance, affected by the cation size and thermal activation. Therefore, NaBH4, KBH4 (at high temperatures), RbBH4 and CsBH4 stabilized in a superposition of P42/nmc, P43m and F43m, or in the Fm3m space group (a disordered face-centered cubic phase) if structural constraints are ignored. These conclusions are instructive to destabilize alkaline metal borohydrides.

This paper experimentally investigated the internal temperature and the facade flame for compartment fires involving circular openings. A series of experiments were carried out by using a reduced-scale model which composed of a cube compartment with various circular openings and a vertical fireproofing board (used as building facade). A porous burner with propane fuel was set inside the compartment as fire source. The internal temperature profile was measured by vertical thermocouple arrays at the inner and outer corners, and the facade flame was captured by a CCD camera from a side view. This paper revealed that: (1) With the same area, maximum heat release rate inside the compartment with circular opening is larger than that with square opening. (2) For relatively larger circular openings, facade flames tend to ceiling jet flame extension. With the increasing of heat release rate, facade flame induced by ceiling jet flame extension will convert to spill fire plume. (3) A dimensionless number R, which represents the ratio of total heat release rate to internal maximum heat release rate, is proposed to distinguish spill fire plume and ceiling jet flame extension when facade flames appear at exterior. (4) A non-dimensional correlation is developed to characterize the facade flame heights for both ceiling jet flame extension and spill fire plume. These findings and results can provide fundamental knowledge for understanding compartment fire with a circular opening.

By doping Zr or Hf into the Fe2P-TiO2 high-pressure phase, we obtain four new Fe2P-type photocatalysts (TiZrO4, Ti2ZrO6, TiHfO4 and Ti2HfO6) through first-principle calculations. Using first principle theory, we discuss the lattice stability and the electronic and the optical properties of these four new compounds. Results show that, compared with the undoped Fe2P-TiO2, these four compounds can be stable under normal conditions. In addition, the band gaps of these four compounds decrease in varying degrees compared with that of the common atmospheric phase of TiO2. By calculating their densities of states, we analyzed the reason for the change in the band gap. What is more, the study of the optical properties showed that the optical absorptivities were larger in the visible band. Results showed these four new Fe2P-type compounds to be photocatalysts with excellent photoelectronic activities.