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This study proposed a method to predict the future aircraft noise level of the international airport by taking Baiyun International Airport (BIA) as an example. BIA was selected to be studied because it is an important international aviation hub in China. The third phase expansion project of BIA is currently in progress, which is the largest airport expansion project in China. The method included the analysis of current operation of the airport, prediction of future operation scenario and operation of the airport, and predicted future population around the airport. Based on the predicted information, this study used CadnaA software to construct and analyze the noise maps of BIA during summer and winter in 2030. The major advancement of this study compared to that of previous research is that this study predicted the noise levels of the airport during summer and winter separately based on the wind direction of airport location, while other research did not take wind direction into consideration. It is found that operation Scenario 1 produces lower noise pollution level in the future compared to Scenario 2 based on the noise exposure results. It is worth mentioning that in 2030 during winter, when the noise level is greater than 70 dB, the noise-exposed area and population of BIA increase by 71.88 and 146.87% (Scenario 1), respectively, compared to current data, which is more serious compared to the growth rate during summer.

This study explores the influence on urban sustainable development performance of residents' resettlement as a result of urban renewal activities, aiming to develop a system dynamics model to simulate the performance of urban sustainable development performance at the perspective of urban renewal. The system dynamics model consists of four subsystems, which are urban economic sector, social service sector, demolition and resettlement sector, and industrial development sector. It was used to simulate the sustainable development performance of Guangzhou city. In the seven scenarios simulated, it is found that increasing the ratio of in-site rehousing and off-site rehousing at the same time can help to promote the sustainable development of the city. The results show that the system dynamics model can effectively simulate the impacts of urban renewal on sustainable development performance, and provides a reference for decision makers to formulate urban sustainable development strategies. [ABSTRACT FROM AUTHOR]

Microwave-absorbing materials with good microwave absorption performance are of great interest for military applications and human health, which is threatened by electromagnetic radiation pollution. Herein, the design and synthesis of multi-componential metal-hybridized graphene composites via freeze drying and pyrolysis of ferrocene hydrazone complex precursor are reported. Various magnetic nanoparticles are loaded on reduced graphene oxide (rGO) via controlling their pyrolysis temperature. The complex electromagnetic parameters of these hybrids are therefore regulated by the hybrid components. Among them, rGO hybridized by the sea-island-like Fe2O3/Fe3O4/FeNi3 multi-componential metals shows a good balance of dielectric and magnetic constants. Thus, the improved impedance matching with free space brings about a superior electromagnetic wave absorption performance, especially on the effective absorption bandwidth. The minimum reflection loss (RL) of the hybrids is as low as −40.3 dB at 11 GHz with the RL bandwidth of −10 dB being 4.55 GHz (from 9.25 to 13.8 GHz).

In this study, the thermal and hydraulic performances of three curved-rectangular vortex generators (VG_1, VG_2, and VG_3) in a compact fin-and-tube heat exchanger were numerically investigated. The secondary flow theory and field synergy principle were employed to characterize the effects of VGs on the flow characteristics and hence the heat transfer enhancement. The thermal and volume goodness enhancement factors were utilized to evaluate the overall performance of VG configurations on the engineering aspects. Results reveal that the secondary flow and synergy between the flow and temperature fields are significantly promoted by applying VGs, by which the heat transfer performance is enhanced. By increasing the tube row number from 3 to 5, the global Nusselt number increases for all the VG cases due to the improved thermal mixing of air flow and fin efficiency. However, in terms of the per-tube heat rejection enhancement, the configuration with tube row number of 3 is most effective for all the VG designs. Results indicate that VG_2 has achieved the best balance between the thermo-hydraulic and volume goodness criterions. The obtained thermal and volume goodness enhancement factors by VG_2 reach as high as 1.42 and 1.24, respectively, manifesting its potential for the development of high-performance and compact fin-and-tube heat exchangers. [ABSTRACT FROM AUTHOR]