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CeO2-ZrO2-La2O3 supported Pt-Pd bimetallic three-way catalysts (0.6Pt-0.4Pd/CZL) were synthesized through the conventional impregnation method and then subjected to severe thermal aging. Reactivating treatments under different temperatures were then applied to the aged catalysts above. Three-way catalytic performance evaluations and dynamic operation window tests along with detailed physio-chemical characterizations were carried out to explore possible structure–activity evolutions during the reactivating process. Results show that the reactivating process conducted at proper temperatures (500~550 °C) could effectively restore the TWC catalytic performance and widen the operation window width. The suitable reactivating temperature ranges are mainly determined by the decomposing temperature of PMOx species, the thermal stability of PM-O-Ce species, and the encapsulation temperature of precious metals by CZL support. Reactivating under appropriate temperature helps to restore the interaction between Pt and CZL support to a certain extent and to re-expose part of the encapsulated precious metals. Therefore, the dynamic oxygen storage/release capacity, redox ability, as well as thermal stability of PtOx species, can be improved, thus benefiting the TWC catalytic performances. However, the excessively high reactivating temperature would cause further embedment of Pd by CZL support, thus leading to a further decrease in both dynamic oxygen storage/release capacity and the TWC catalytic performance after reactivating treatment. [ABSTRACT FROM AUTHOR]

Monitoring of rice planting areas plays an important role in maintaining food security. With powerful automatic feature extraction capability, crop mapping based on deep learning methods has become one of the most important research directions of crop remote sensing recognition. However, the training of deep learning models often requires a large number of samples, which restricts the application of these models in areas with a lack of samples. To address this problem, based on time-series Sentinel-1 SAR data, this study pre-trained the temporal feature-based segmentation (TFBS) model with an attention mechanism (attTFBS) using abundant samples from the United States and then performed an inter-continental transfer of the pre-trained model based on a very small number of samples to obtain rice maps in areas with a lack of samples. The results showed that an inter-continental transferred rice mapping model was feasible to achieve accurate rice maps in Northeast China (F-score, kappa coefficient, recall, and precision were 0.8502, 0.8439, 0.8345, and 0.8669, respectively). The study found that the transferred model exhibited a strong spatiotemporal generalization capability, achieving high accuracy in rice mapping in the three main rice-producing regions of Northeast China. The phenological differences of rice significantly affected the generalization capability of the transferred model, particularly the significant differences in transplanting periods, which could have resulted in a decrease in the generalization capability of the model. Furthermore, the study found that the model transferred based on an extremely limited number of samples could attain a rice recognition accuracy equivalent to that of the model trained from scratch with a substantial number of samples, indicating that the proposed method possessed strong practicality, which could dramatically reduce the sample requirements for crop mapping based on deep learning models, thereby decreasing costs, increasing efficiency, and facilitating large-scale crop mapping in areas with limited samples. [ABSTRACT FROM AUTHOR]

Summary: The photovoltaic‐thermoelectric hybrid system (PVTE) is less sensitive to the photon wavelength than the pure PV system. This phenomenon can make the PVTE to be a good method of obtaining electrical energy from solar energy. A challenge of this system is how to distribute the energy in the working process. To solve this problem, this paper establishes a thermodynamic model to study the energy matching mechanism of the hybrid system. The influence of dynamic solar radiation has been considered in the model. The result indicates that the relationship between the PVTE efficiency and the PV bandgap looks like a "reverse U" (rises first and falls later). The impacts of the optical concentration ratio and the TE parameters on the optimal PV bandgap are studied. No matter how these two parameters change, the optimal PV bandgap of the PVTE is around 1.15 eV. It illustrates that the energy match does not depend on the solar radiation and the TE parameters. The effect of the phase change material has also been considered. The melting temperature, mass and heat capacity of the phase change material have been considered in the numerical model. The melting temperature is proved to be important for determining whether it needs to use the phase change material and how much heat should be stored. [ABSTRACT FROM AUTHOR]

The distribution of water wall temperature in the ultra-supercritical (USC) boilers was obtained by establishing a coupled heat transfer model. The reliability of this model has been validated through the comparisons of simulated and measured water wall temperatures along different dimensions in the furnace of reference USC boiler. Then, the effect of flame offset on water wall tube temperature in 600°C and 700°C USC boilers was investigated by importing the flame offset variables into the coupled model. The water wall temperature distribution is significantly influenced by flame offset, and both the fluctuation and growth rate of temperature are increased with the ascent of flame offset distance, especially on the furnace walls that flame deviates toward. The radiative and convective heat flux to water walls is strengthened simultaneously during the flame offset process, resulting in the local overheating of water wall. In the 600°C USC boilers, when the distance of flame offset exceeds 5 m, multiple peak distribution of wall temperatures appears, which can increase the burst risk of water wall tubes because of shear stress inside the tube material. The maximal distance of flame offset should be limited to 3 m to avoid the tube burst accidents. In the 700°C USC unit, the variation tendency of water wall temperature is resemble with that in 600°C USC unit, but the fluctuation of wall temperature is larger. As the flame offset distance approaches 3 m, the maximal water wall temperature reaches 595°C, which greatly exceeds the material allowable temperature in the 600°C USC unit. The material of water wall tubes with allowable temperature of 605°C is recommended for the 700°C USC unit. Based on the thermal security of metal material, the maximal distance of flame offset should be yielded to 2 m. [ABSTRACT FROM AUTHOR]

The discrete element method (DEM) is used to simulate two types of mixing processes (radial mixing and axial mixing) of particles with and without cohesive interparticle forces in a two-dimensional (2D) fluidized bed. By using the Ashton index, the mixing degree is quantified and the differences between the mixing characteristics of particles with and without cohesive interparticle forces are compared. The cohesive interparticle forces, which impair bubble behaviors, can apparently weaken the mixing process and prolong the mixing time. This effect increases with increasing cohesive interparticle force. Radial mixing, which is mainly dependent on the convective mixing caused by bubbles, is relatively sensitive to cohesive interparticle force and shows a long mixing time, while axial mixing, which is mainly induced by the bubble wake, is less sensitive to cohesive interparticle force and presents a fast mixing process. Finally, to weaken the effect of cohesive interparticle force, an uneven air distribution is introduced, which greatly improves the mixing process by changing the bubble movement. This method may be helpful for the reduction of particle agglomeration in high-temperature fluidized beds. [ABSTRACT FROM AUTHOR]