Assembly process based on supply chain management of prefabricated houses using BIM

The assembly of modular containers using building information modelling (BIM) technologies was studied. The purpose of this study was to analyse the literature on prefabricated (prefab) houses and explore the concept of creating a digital prototype of a building based on Huoshenshan hospital using Autodesk Revit software. This hospital was constructed to treat Covid-19 patients in early 2020. The article describes the methodology of installing modular containers and assembly structures using BIM technologies for rapid construction. The results of this study showed that building object implementation depends directly on a proper model with a step-by-step mechanism for installation. Due to the supply of prefab structures at the construction site, both initial project cost and project time can be reduced. Prefab house technology demonstrated the high efficiency of using BIM technology in the assembly of Huoshenshan hospital, which was constructed in 10 days. The need for information modelling data exchange with modern technology and systems, which allows the team to become acquainted with the project before installation work starts at the construction site, is investigated.

Chemical composition characteristics of PM2.5 in Henan Province during the Spring Festival and COVID-19 outbreak

In January 2020, a new coronavirus epidemic broke out in China, when the emission characteristics of air pollution have changed significantly. To study the characteristics of PM2.5 components under this scenario, a series of online observation instruments were used in Zhengzhou, Anyang, and Xinxiang cities from January 1 to February 13, 2020. The study period is divided into pre-holiday (January 1 to 23), mid-holiday outbreak (January 24 to 31), and post-holiday outbreak (February 1 to 13) based on the Spring Festival holiday and the outbreak of the epidemic. Affected by the outbreak and favorable meteorological conditions, the concentrations of other pollutants except O3 in the three cities during the post-holiday outbreak were significantly lower than those during pre-holiday, especially NO2 decreased by 65%, 52%, and 72% and PM2.5 decreased by 51%, 55%, and 54%, respectively. Note that the pollutants remained high concentration, indicating that a large improvement in winter air quality in Henan Province will face great challenges in the future. Secondary inorganic aerosols and organic matter were the main components of PM2.5 during the observation periods. During the mid-holiday outbreak, the three cities were less affected by fireworks, and the contribution of nitrate and dust decreased slightly compared to before the pre-holiday. After the holiday, the proportions of nitrate decreased by 10.6%, 4.1%, and 4% in Zhengzhou, Anyang, and Xinxiang, respectively. In contrast, the proportions of sulfate and secondary organic carbon increased. Taking Zhengzhou City as an example to analyze the formation of nitrate, compared to pre-holiday, the proportions of nitrate under different pollution levels in the post-holiday outbreak have decreased, but nitrate was still the highest proportion of PM2.5 during the polluted period. The characteristics of diurnal variation indicate that the increase in O3 concentration and humidity in the atmosphere during the post-holiday outbreak may promote the conversion of NO2. Therefore, the next step should be to adopt the coordinated management and control of PM2.5 and O3 and pay attention to the coordinated reduction of NO2 and VOCs. © 2020, Editorial Board of China Environmental Science. All right reserved.