We reported a facile one-pot polyol route for the fabrication of CoNi/nitrogen-doped graphene hybrids as synergistic microwave absorber. Microstructure investigations suggest that all the CoNi ...nanocrystals are uniformly anchored on the nitrogen-doped graphene nanosheets without aggregation and the hybrids are stable under ultrasound treatment, which suggest that these nonvalent CoNi alloys are in-situ grown on nitrogen-doped graphene with a strong interaction. Taking both the synergistic benefits of magnetic CoNi nanocrystals and electric nitrogen-doped graphene, the CoNi/nitrogen-doped graphene hybrids show a maximum reflection loss of −22 dB at 10 GHz with a matching thickness of only 2.0 mm, and the effective absorption bandwidth with reflection loss exceeding −10 dB is 3.6–18 GHz with the absorber thickness of 1.35–5.0 mm. Compared with the single CoNi nanocrystals and graphene oxide, the CoNi/nitrogen-doped graphene hybrids show improved microwave absorption properties. These results indicate that the interface interactions and synergistic effect between the CoNi nanocrystals and nitrogen-doped graphene play a significant role on the enhancement of microwave absorption properties. This work suggests that the CoNi/nitrogen-doped graphene hybrids can be used as candidate materials for the design and manufacture of electronic nanodevices with high efficient microwave absorption properties.
Human trajectory prediction is challenging and critical in various applications (e.g., autonomous vehicles and social robots). Because of the continuity and foresight of the pedestrian movements, the ...moving pedestrians in crowded spaces will consider both spatial and temporal interactions to avoid future collisions. However, most of the existing methods ignore the temporal correlations of interactions with other pedestrians involved in a scene. In this work, we propose a Spatial-Temporal Graph Attention network (STGAT), based on a sequence-to-sequence architecture to predict future trajectories of pedestrians. Besides the spatial interactions captured by the graph attention mechanism at each time-step, we adopt an extra LSTM to encode the temporal correlations of interactions. Through comparisons with state-of-the-art methods, our model achieves superior performance on two publicly available crowd datasets (ETH and UCY) and produces more "socially" plausible trajectories for pedestrians.
Abstract
Water evaporation is a natural phase change phenomenon occurring any time and everywhere. Enormous efforts have been made to harvest energy from this ubiquitous process by leveraging on the ...interaction between water and materials with tailored structural, chemical and thermal properties. Here, we develop a multi-layered interfacial evaporation-driven nanogenerator (IENG) that further amplifies the interaction by introducing additional bionic light-trapping structure for efficient light to heat and electric generation on the top and middle of the device. Notable, we also rationally design the bottom layer for sufficient water transport and storage. We demonstrate the IENG performs a spectacular continuous power output as high as 11.8 μW cm
−2
under optimal conditions, more than 6.8 times higher than the currently reported average value. We hope this work can provide a new bionic strategy using multiple natural energy sources for effective power generation.
A new electrochemically driven process (E-peroxone) was developed to treat methylene blue (MB) wastewater. During the E-peroxone process, ozone generator effluent (O2 and O3 gas mixture) is ...continuously sparged into a reactor that has a carbon-polytetrafluorethylene (carbon-PTFE) cathode, which can electrochemically convert the sparged O2 to H2O2 effectively. The in situ generated H2O2 then reacts with the sparged O3 to produce hydroxyl radicals (OH), which are a much stronger oxidant than O3. Thus, by utilizing the sparged O2 that has little value in ozonation processes to produce H2O2 in situ, the E-peroxone process can achieve the synergy of O3 and H2O2 (peroxone) on pollutant degradation. The E-peroxone process therefore mineralized MB much more effectively than ozonation. The total organic carbon removal was 93 and 22% after 2h of the E-peroxone and ozonation treatment, respectively. The E-peroxone process may thus offer a simple and effective method to degrade ozone-refractory organic pollutants in wastewater.
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► A new electrochemically driven process (electro-peroxone) was developed. ► H2O2 is electro-generated in situ from O2 in sparged O2 and O3 gas mixture. ► The E-peroxone process can achieve synergy of H2O2 and O3 for organic degradation. ► The E-peroxone process is an effective method for degrading refractory organics.
Knowledge of the contribution that individual countries have made to global radiative forcing is important to the implementation of the agreement on "common but differentiated responsibilities" ...reached by the United Nations Framework Convention on Climate Change. Over the past three decades, China has experienced rapid economic development, accompanied by increased emission of greenhouse gases, ozone precursors and aerosols, but the magnitude of the associated radiative forcing has remained unclear. Here we use a global coupled biogeochemistry-climate model and a chemistry and transport model to quantify China's present-day contribution to global radiative forcing due to well-mixed greenhouse gases, short-lived atmospheric climate forcers and land-use-induced regional surface albedo changes. We find that China contributes 10% ± 4% of the current global radiative forcing. China's relative contribution to the positive (warming) component of global radiative forcing, mainly induced by well-mixed greenhouse gases and black carbon aerosols, is 12% ± 2%. Its relative contribution to the negative (cooling) component is 15% ± 6%, dominated by the effect of sulfate and nitrate aerosols. China's strongest contributions are 0.16 ± 0.02 watts per square metre for CO2 from fossil fuel burning, 0.13 ± 0.05 watts per square metre for CH4, -0.11 ± 0.05 watts per square metre for sulfate aerosols, and 0.09 ± 0.06 watts per square metre for black carbon aerosols. China's eventual goal of improving air quality will result in changes in radiative forcing in the coming years: a reduction of sulfur dioxide emissions would drive a faster future warming, unless offset by larger reductions of radiative forcing from well-mixed greenhouse gases and black carbon.
Degradation of a synthetic azo dye, Orange II, by electro-peroxone (E-peroxone) treatment was investigated. During the E-peroxone process, ozone generator effluent (O2 and O3 gas mixture) was ...continuously sparged into an electrolysis reactor, which was equipped with a carbon-polytetrafluorethylene (carbon-PTFE) cathode to electrochemically convert the sparged O2 to H2O2. The in-situ generated H2O2 then reacted with the sparged O3 to produce •OH, which can oxidize ozone-refractory organic pollutants effectively. Thus, by simply combining conventional ozonation and electrolysis processes, and using a cathode that can effectively convert O2 to H2O2, the E-peroxone process degraded Orange II much more effectively than the two processes individually. Complete decolorization and 95.7% total organic carbon (TOC) mineralization were obtained after 4 and 45 min of the E-peroxone treatment, respectively. In comparison, only 55.6 and 15.3% TOC were mineralized after 90 min of the individual ozonation and electrolysis treatments, respectively. In addition to its high efficiency, the E-peroxone process was effective over a wide range of pH (3–10) and did not produce any secondary pollutants. The E-peroxone process can thus provide an effective and environmentally-friendly alternative for wastewater treatment.
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•H2O2 is produced electrochemically from O2 in sparged gas mixture of O2 and O3.••OH is formed via the peroxone reaction of in-situ generated H2O2 with sparged O3.•E-peroxone is effective at decolorizing and mineralizing synthetic dye wastewater.•E-peroxone process does not generate secondary pollutants.•E-peroxone is an effective and environmentally-friendly water treatment technology.
Electro-peroxone (E-peroxone) treatment of the anti-inflammatory drug ibuprofen aqueous solution was investigated in this study. The E-peroxone process combined conventional ozonation with ...electrolysis processes, and used a carbon-polytetrafluorethylene cathode to electrochemically generate H2O2 from O2 in the sparged ozone generator effluent (O2 and O3 mixture). The in-situ generated H2O2 then reacted with the sparged O3 to produce aqueous •OH, which can in turn oxidize pollutants effectively in the bulk solution. The E-peroxone process overcomes several intrinsic limitations of conventional ozonation and electrolysis processes for pollutant degradation such as the selective oxidation with O3 and mass transfer limitations of pollutants to the electrodes, and thus significantly enhanced both ibuprofen degradation and total organic carbon (TOC) mineralization. Results show that ibuprofen could be completely degraded much more rapidly in the E-peroxone process (e.g., 5–15 min under all tested reaction conditions) than in ozonation (≥30 min) and electrolysis (several hours) processes. In addition, thanks to the powerful and non-selective oxidation capacity of •OH, toxic intermediates formed during ibuprofen degradation could be completely mineralized in the E-peroxone process. The E-peroxone effluent (2 h) thus exhibited much lower toxicity (5% inhibition of bioluminescence of Vibrio fisheri) than the ozonation and electrolysis effluents (22% and 88% inhibition, respectively). The results of this study indicate that the E-peroxone process may provide a promising technology for pharmaceutical wastewater treatment.
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•E-peroxone combines ozonation with electrolysis to enhance ibuprofen degradation.•H2O2 is electro-generated from O2 in sparged O2 and O3 gas mixture at the cathode.••OH is produced from the reaction of sparged O3 with electro-generated H2O2.•Ibuprofen is mineralized much faster in E-peroxone than in ozonation and electrolysis.•E-peroxone may provide a promising technology to treat pharmaceutical wastewater.
As a typical sequence to sequence task, sign language production (SLP) aims to automatically translate spoken language sentences into the corresponding sign language sequences. The existing SLP ...methods can be classified into two categories: autoregressive and non-autoregressive SLP. The autoregressive methods suffer from high latency and error accumulation caused by the long-term dependence between current output and the previous poses. And non-autoregressive methods suffer from repetition and omission during the parallel decoding process. To remedy these issues in SLP, we propose a novel method named Pyramid Semi-Autoregressive Transformer with Rich Semantics (PSAT-RS) in this paper. In PSAT-RS, we first introduce a pyramid Semi-Autoregressive mechanism with dividing target sequence into groups in a coarse-to-fine manner, which globally keeps the autoregressive property while locally generating target frames. Meanwhile, the relaxed masked attention mechanism is adopted to make the decoder not only capture the pose sequences in the previous groups, but also pay attention to the current group. Finally, considering the importance of spatial-temporal information, we also design a Rich Semantics embedding (RS) module to encode the sequential information both on time dimension and spatial displacement into the same high-dimensional space. This significantly improves the coordination of joints motion, making the generated sign language videos more natural. Results of our experiments conducted on RWTH-PHOENIX-Weather-2014T and CSL datasets show that the proposed PSAT-RS is competitive to the state-of-the-art autoregressive and non-autoregressive SLP models, achieving a better trade-off between speed and accuracy.
Timely and accurate information about floating macroalgae blooms (MAB), including their distribution, movement, and duration, is crucial in order for local government and residents to grasp the whole ...picture, and then plan effectively to restrain economic damage. Plenty of threshold-based index methods have been developed to detect surface algae pixels in various ocean color data with different manners; however, these methods cannot be used for every satellite sensor because of the spectral band configuration. Also, these traditional methods generally require other reliable indicators, and even visual inspection, in order to achieve an acceptable mapping of MAB that appears under diverse environmental conditions (cloud, aerosol, and sun glint). To overcome these drawbacks, a machine learning algorithm named Multi-Layer Perceptron (MLP) was used in this paper to establish a novel automatic method to monitor MAB continuously in the Yellow Sea, using Geostationary Ocean Color Imager (GOCI) imagery. The method consists of two MLP models, which consider both spectral and spatial features of Rayleigh-corrected reflectance (R
) maps. Accuracy assessment and performance comparison showed that the proposed method has the capability to provide prediction maps of MAB with high accuracy (F1-score approaching 90% or more), and with more robustness than the traditional methods. Most importantly, the model is practically adaptable for other ocean color instruments. This allows customized models to be built and used for monitoring MAB in any regional areas. With the development of machine learning models, long-term mapping of MAB in global ocean is conducive to promoting the associated studies.
Although increasing superwetting membranes have been developed for separating oil–water emulsions based on the “size-sieving” mechanism, their pores are easily blocked and fouled by the intercepted ...emulsified droplets, which would result in a severe membrane fouling issue and a sharp decline in flux. Instead of droplet interception, a fiber-based coalescer separates oil/water emulsions by inducing the emulsified droplets to coalesce and transform into layered oil/water mixtures, exhibiting an ability to work continuously for a long time with high throughput, which makes it a promising technology for emulsion treatment. However, the underlying mechanism of the separation process is not well understood, which makes it difficult to further improve the separation performance. Hence, in this work, the dynamic behaviors of water-in-oil emulsified droplets on the surface of the coalescing fiber were numerically investigated based on the phase-field model. The attachment, transport, and detachment behaviors of droplets on fibers were directly observed, and the effects of fiber wettability, orientation, arrangement, and fluid speed were studied in detail. First, it was observed that the droplets will move downstream along the fiber surface under the effect of fluid shear, and the large droplets tend to coalesce with their downstream small droplets on the same fiber surface because they move faster compared to the small droplets. Second, it was found that the emulsified droplet will spontaneously transport to the intersection of two angled fibers under the drive of asymmetric Laplace pressure, which demonstrated that the emulsified droplets tend to gather at the intersection of fibers when permeating through a coalescing medium. Third, it was found that the detachment behaviors of droplets from the fiber surface are strongly affected by their size, fiber wettability, and fluid velocity. In addition, the results of our simulation show that the backside of two closely attached fibers can further inhibit the detachment of droplets. We truly believe that our research results are of significance to optimize the parameters of a fiber-based coalescer for separating oil–water emulsions and to develop novel oil/water separators.
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