Search

The phase structure of Sm2Fe17NX(SmFeN)/LaMA(LaMgAlO) composite wave-absorbing coating samples with different mass ratios (2:1, 1:1, 1:2) plasma sprayed at 35 kW as well as the values of electromagnetic parameters (ε', ε", μ', μ") and electromagnetic reflectance RL of the samples within the electromagnetic wave frequency band of 0-18 GHz were observed and analyzed, and the its electromagnetic loss mechanism was investigated. The results show that the SmFeN content has a large influence on the phase composition and wave-absorbing properties of the sprayed samples. The sprayed samples include Fe, Fe8N, Fe16N2, Al2O3, AlN, Fe12Sm, La3MgAlO7 and LaMgAl11O19 phases. The SmFeN increases the relative content of the Fe, Fe8N and Fe16N2 phases, decreases the relative content of the Fe12Sm, La3MgAlO7 and LaMgAl11O19 phases, and has no effect on the AlN phase. The amorphous phase appears at high temperatures, and the relative intensity of the amorphous phase increases as the temperature rises, resulting in poor wave-absorbing properties of the samples at high temperatures. The relative content of LaMgAl11O19 decreases the ε', ε" of the samples, optimizing the impedance matching of the sprayed samples. The relative content of AlN increases the valley of ε' and the peak of ε" to the high frequency. The mass ratio of the sprayed sample with the best performance is SmFeN:LaMA=1:2, the reflectivity reaches -40.31 dB at 4.24 GHz, 4.83 mm, and the bandwidth and thickness range of the effective absorption (RL<-10 dB) are 3.61-6.94 GHz, 2.93-5 mm and 8.4-12.2 GHz, 1.98-3.45 mm, respectively. The lowest reflectance of the 1:1 ratio sprayed samples at 40 °C, 400 °C, and 700 °C are -5.46 dB, -3.62 dB, and -0.37 dB in the 8-18 GHz bands respectively. The room temperature test values of the bowtie beams show that the RL values resulted from electromagnetic parameters are agreeable with the test values. [ABSTRACT FROM AUTHOR]

Precise prediction of the power generation of photovoltaic (PV) stations on the island contributes to efficiently utilizing and developing abundant solar energy resources along the coast. In this work, a hybrid short-term prediction model (ICMIC-POA-CNN-BIGRU) was proposed to study the output of a fishing–solar complementary PV station with high humidity on the island. ICMIC chaotic mapping was used to optimize the initial position of the pelican optimization algorithm (POA) population, enhancing the global search ability. Then, ICMIC-POA performed hyperparameter debugging and L2-regularization coefficient optimization on CNN-BIGRU (convolutional neural network and bidirectional gated recurrent unit). The L2-regularization technique optimized the loss curve and over-fitting problem in the CNN-BIGRU training process. To compare the prediction effect with the other five models, three typical days (sunny, cloudy, and rainy) were selected to establish the model, and six evaluation indexes were used to evaluate the prediction performance. The results show that the model proposed in this work shows stronger robustness and generalization ability. K-fold cross-validation verified the prediction effects of three models established by different datasets for three consecutive days and five consecutive days. Compared with the CNN-BIGRU model, the RMSE values of the newly proposed model were reduced by 64.08%, 46.14%, 57.59%, 60.61%, and 34.04%, respectively, in sunny, cloudy, rainy, continuous prediction 3 days, and 5 days. The average value of the determination coefficient R 2   of the 20 experiments was 0.98372 on sunny days, 0.97589 on cloudy days, and 0.98735 on rainy days. [ABSTRACT FROM AUTHOR]

The United Nations International Children's Emergency Fund (UNICEF) initiatives of Child-Friendly Cities have operated in more than 3000 cities around the world. However, the concept of making the city child-friendly has not been extensively recognized in China. This article aims to report a regeneration project in a migrant workers' community, the Mingdong, and is used to illustrate the reactions of residents to youth participation (youth civic engagement) and the project through an international workshop. The article concludes with a discussion of how social workers help in the social development of migrant communities by promoting youth participation, community social awareness and social cohesiveness. [ABSTRACT FROM AUTHOR]

Most of the exhaust temperature of ships is above 300℃, usually this part of waste heat would be directly discharged into the environment, not fully utilized. In order to improve the energy efficiency ratio of ship storage and transportation more effectively, domestic and foreign counterparts have done a lot of technical research on the recovery and utilization of ship waste heat, but most of them are based on a single application perspective. Emphasizing the application of multi-angle combined waste heat, driven by waste heat for CO2 supercritical power generation coupling trans-critical refrigeration system was proposed and designed. While the combined system recovered waste heat for power generation, the functions of refrigerating cooling and seawater desalination were realized by using the properties of CO2 working medium. Taking Fuyuan Yu 7861 ocean-going fishing boat as a design case, the relevant thermal calculation and equipment matching of CO2 supercritical power-transcritical refrigeration system driven by waste heat recovery were targeted. The results showed that the total power consumption of the system is 34.171KW, the waste heat power generation efficiency is 12.9%, the refrigeration performance coefficient is 2.368, the energy saving effect is remarkable, and the energy saving and emission reduction are realized.