In this paper, CoCrFeNiTix high entropy alloy (HEA) coatings were prepared on the surface of Q235 steel by laser cladding. The microstructure, microhardness, and corrosion resistance of the coatings ...were studied. The mechanism of their corrosion resistance was elucidated experimentally and by first-principles calculations. The results show that CoCrFeNiTi0.1 adopts a face-centered cubic (FCC) phase, CoCrFeNiTi0.3 exhibits an FCC phase and a tetragonal FeCr phase, and CoCrFeNiTi0.5 adopts an FCC phase, a tetragonal FeCr phase, and a rhombohedral NiTi phase. The FCC phase, tetragonal FeCr phase, rhombohedral NiTi phase, and hexagonal CoTi phase are all observed in the CoCrFeNiTi0.7 HEA. The alloys assume the dendritic structure that is typical of HEAs. Ni and Ti are enriched in the interdendritic regions, whereas Cr and Fe are enriched in the dendrites. With increasing Ti content, the hardness of the cladding layers also increases due to the combined effects of lattice distortion and dispersion strengthening. When exposed to a 3.5 wt.% NaCl solution, pitting corrosion is the main form of corrosion on the CoCrFeNiTix HEA surfaces. The corrosion current densities of CoCrFeNiTix HEAs are much lower than those of other HEAs. As the Ti content increases, the corrosion resistance is improved. Through X-ray photoelectron spectroscopy (XPS) and first-principles calculations, the origin of the higher corrosion resistance of the coatings is connected to the presence of a dense passivation film. In summary, the corrosion resistance and mechanical properties of CoCrFeNiTi0.5 alloy are much better than the other three groups, which promotes the development of HEA systems with high value for industrial application.
In order to solve the problem of too large computer overhead for convolutional neural network in the rescue action recognition, this paper proposes a rescue action recognition method combining ...spatiotemporal decomposition network and channel attention mechanism. After adding the channel attention mechanism, the model can generate a weight value for each feature channel, and then weight the normalized weight to each feature channel to improve the recognition accuracy of the model. The combined network model has better performance in both computer overhead and recognition accuracy, and the recognition accuracy has improved compared with the original model (S3D) in the case of only RGB video as input on rescue action data. In addition, the recognition accuracy on the public UCF-101 and KTH datasets has also improved. The experiment results show the proposed method can effectively improve the accuracy of action recognition in both the rescue action and public datasets.
Rational tailoring of the atomic structure of photocatalysts with multiple functions to enhance the carrier transfer efficiency and surface activation of carbon nitride (C
3
N
4
) is promising and a ...challenge. Here, we make the first report of a facile strategy to construct amphiphilic carbon and C-O-C chain linked terminal melem units in functional carbon nitride (COCN)
via
copolymerizing formaldehyde with melem. By integrating the amphiphilic carrier bridge of carbon and C-O-C chains into the framework, the photogenerated carrier mobility and activated species (superoxide radicals, singlet oxygen) as well as surface interaction are significantly improved. Consequently, the optimal tailoring of C
3
N
4
attains superior photocatalytic activity for hydrogen production (34.9 μmol h
−1
) and selective oxidation of sulfide to sulfoxide using air (nearly 100% conversion and selectivity after 3 h of illumination), which is about 7 times higher than that of pristine C
3
N
4
. This study provides deep insight into and strategies for the atomic tailoring of carrier transfer and surface reaction over organic-based photocatalysts.
Rational tailoring of the atomic structure of photocatalysts with multiple functions to enhance the carrier transfer efficiency and surface activation of carbon nitride (C
3
N
4
) is promising and a challenge.
Ether-rich tetraethylene glycol is an alternative SO
2
absorbent due to the good solubility and high stability. Due to the high viscosity of tetraethylene glycol, it is usually necessary to add an ...appropriate amount of water to reduce the viscosity. In this case, insight into the interaction mechanism between molecules can guide the most reasonable amount of water to be added to tetraethylene glycol in the actual SO
2
gas separation process. In this work, the structure–activity relationship of SO
2
in tetraethylene glycol and its aqueous solution was studied by measuring the SO
2
solubility and spectral features. Using an isochoric saturation method, the solubility of SO
2
in tetraethylene glycol (1) + water (2) mixtures was determined at 303.2 K and pressures up to 120 kPa. It was found that the solubility of SO
2
increases gradually with increasing mass fraction of tetraethylene glycol and the dissolution process of SO
2
conforms to Henry’s law within the current experimental conditions. The Henry’s constants were further calculated based on solubility data. Furthermore, FTIR, UV–Vis, and
1
H NMR spectroscopic characteristic for dissolved SO
2
into tetraethylene glycol (1) + water (2) mixture was also investigated, revealing significant information about the SO
2
absorption mechanism.
Densities and viscosities for the binary system of tetraethylene glycol (1) + water (2) at
T
= (298.15 to 323.15) K were measured as a function of composition under atmospheric pressure. The excess ...properties, including excess molar volumes (
V
M
E
), viscosity deviations (Δ
η
), and the excess Gibbs free energy of activation for viscous flow (Δ
G
*
E
) were calculated by using density and viscosity data, respectively. Excess properties indicated that there are hydrogen bonding interactions between tetraethylene glycol and water molecules, which are investigated in detail by FTIR and UV–Vis spectra.
In view of the increasingly serious harm of CO2 to the environment, it is highly desirable to develop effective CO2 absorbents. In this work, we demonstrated an efficient absorption of CO2 by blends ...of protic ionic liquids (PILs) plus amines. The density and viscosity of investigative four PILs-amine mixtures were measured. By systematically studying the effects of the solution ratio, temperature, CO2 partial pressure, and water content on the absorption of CO2, it is found that the 3-dimethylamino-1-propylamine acetate (DMAPAHOAc) plus ethanediamine (EDA) mixture shows the highest CO2 uptake of 0.295 g CO2 per g absorbent at 50 °C and 1 bar and a further increase in the absorption of CO2 to 0.299 g/g by adding water with a mass fraction of 20%. Furthermore, the absorption mechanism of CO2 in the presence and absence of water has also been investigated by FTIR and NMR spectra.
The formation of intermetallic compounds (IMC) at the Al/Fe interface determined the mechanical property of steel-aluminum welded joint. To understand the interfacial microstructure evolution and ...relate diffusion mechanism of atoms cross the Al/Fe interface, the effect of welding parameters on the interfacial IMC was studied, and the molecular dynamics method (MD) was used to simulate the diffusion process of Al and Fe atoms. Four temperatures (950 K, 1000 K, 1050 K, and 1100 K) were selected in the simulation model. The interfacial IMC are distributed in a laminar pattern, and their physical phases are mainly composed of Fe2Al5, controlling the Al/Fe atomic ratio of 5:2 in the IMC configuration, the Embedded Atom Method (EAM) potential is used to describe the interactions between Al and Fe atoms. In the Al-Fe system IMC conformation, the mean square displacement and diffusion (MSD) coefficient of Al atoms at different temperatures were small, and the main diffusion path is the Al atoms across the IMC conformation into the Fe crystal structure. The diffusion in the IMC conformation was mainly along the direction perpendicular to the interface. The diffusion mechanisms were mainly vacancy diffusion and interstitial diffusion mechanisms.
An accurate crime prediction and risk estimation can help improve the efficiency and effectiveness of policing activities. However, reports have revealed that biases like racial prejudice could exist ...in policing enforcement, and trained predictors may inherit them. In this work, we study the possible reasons and countermeasures to this problem, using records from the New York frisk and search program (NYCSF) as the dataset. Concretely, we provide analysis on the possible origin of this phenomenon from the perspective of risk discrepancy, and study it with the scope of selection bias. Motivated by theories in causal inference, we propose a re-weighting approach based on propensity score to balance the data distribution, with respect to the identified treatment: search action. Naively applying existing re-weighting approaches in causal inference is not suitable as the weight is passively estimated from observational data. Inspired by adversarial learning techniques, we formulate the predictor training and re-weighting as a min-max game, so that the re-weighting scale can be automatically learned. Specifically, the proposed approach aims to train a model that: 1) able to balance the data distribution in the searched and un-searched groups; 2) remain discriminative between treatment interventions. Extensive evaluations on real-world dataset are conducted, and results validate the effectiveness of the proposed framework.
•Different strategies for compositing daily EVI2 from 10-min AHI data were assessed.•Mean value compositing using data around solar noon minimized anisotropic effects.•Composited AHI daily EVI2 time ...series have 5.3 times more observations than MODIS.•Phenology dates were successfully retrieved from composited AHI EVI2 time series.•AHI can reduce uncertainty in phenology monitoring with more valid data and less gaps.
Sensors onboard the new generation of geostationary (GEO) satellites launched over past few years have much improved radiometric and temporal resolutions. As one of the latest GEO sensors, the Japanese Himawari-8 Advanced Himawari Imager (hereafter H8/AHI) has temporal resolution of 10 minutes and spectral bands similar to MODIS. Observations from H8/AHI therefore have the potential to improve the precision of vegetation phenology monitoring by significantly shortening the compositing period. In this study, we evaluated methods for compositing daily 2-band Enhanced Vegetation Index (EVI2) from 10-minutes H8/AHI observations at six study sites in northern China encompassing forest, cropland, and grassland. After screening the cloudy observations by a physics-based cloud detection algorithm, key phenological metrics were retrieved from the composited AHI EVI2. H8/AHI 10-min raw EVI2 showed significant diurnal variations that are mainly associated with sun angle variations. By calculating the daily average EVI2 values in different time intervals, we concluded that the mean value using a fixed time window (10:30–13:30) centered around local solar noon effectively reduced the anisotropy effect from the diurnal sun-angle variations, leading to stable EVI2 time series suitable for extracting phenological metrics. On average, the amount of the composited H8/AHI EVI2 time-series data was 5.3 times more than the Terra/Aqua combined MODIS EVI2 product per year and the average size (width) of the gaps in H8/AHI EVI2 time series was 75% smaller than that of the MODIS. Our results demonstrated the promising capability of the new generation GEO satellite for generating time series vegetation index with fewer cloud-induced gaps and higher temporal resolution, hence improving the monitoring of global vegetation phenology and ecosystem responses to climate change.
In order to improve the service life of the V-ribbed belt and the ride comfort of the vehicle, the friction noise of V-ribbed belt was studied by simulation and experiment. A theoretical model of ...V-ribbed belts vibration is established, and the conditions for unstable vibration are derived. Based on the theory of mode coupling, the causes of high frequency friction noise of V-ribbed belts are analyzed, and it is considered that the coupling between the vibration of the V-ribbed belts and the natural frequency of the belts’ cross section causes the self-excited vibration of the belt, resulting in high frequency friction noise. Firstly, ANSYS Workbench is used to identify the belts’ cross sections with 3, 4, and 6 wedges, and the natural frequencies of the belts’ cross sections are obtained. Then on the belt drive friction tester, the influences of tension and relative sliding speed on the frequency of high frequency friction noise is studied using a single factor test method, and the frequency response curve of high frequency friction noise is also analyzed. The results of the experiment and simulation show that the transverse vibration of the V-ribbed belts is closely related to the phase and amplitude of the high frequency friction noise, and the changes in tension and relative sliding speed do not affect the frequency of the high frequency friction noise. The frequency of high frequency friction noise has a good consistency with the natural frequency of belts’ cross section, which shows that mode coupling causes the strong self-excited vibration of the V-ribbed belts and the high frequency friction noise. It provides a method and theoretical basis for the control of friction noise.
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