Discussion on the Improvement of Technical Safety Scheme Compilation for Hazardous and Ultrahazardous Projects

This paper reviews the summary and analysis of special technical safety schemes for hazardous and ultrahazardous activities, supported by housing scaffolding, installation, and dismantling of outer wall attached tower crane, deep foundation pit with supporting structure, municipal bridge box girder formwork support, as well as grooved Larsen steel sheet pile, which are commonly seen in recent years, so as to enhance the pertinence, rationality, and economy of the special program to strengthen safety.

Mapping Blue and Red Color-Coated Steel Sheet Roof Buildings over China Using Sentinel-2A/B MSIL2A Images

Accurate and efficiently updated information on color-coated steel sheet (CCSS) roof materials in urban areas is of great significance for understanding the potential impact, challenges, and issues of these materials on urban sustainable development, human health, and the environment. Thanks to the development of Earth observation technologies, remote sensing (RS) provides abundant data to identify and map CCSS materials with different colors in urban areas. However, existing studies are still quite challenging with regards to the data collection and processing costs, particularly in wide geographical areas. Combining free access high-resolution RS data and a cloud computing platform, i.e., Sentinel-2A/B data sets and Google Earth Engine (GEE), this study aims at CCSS material identification and mapping. Specifically, six novel spectral indexes that use Sentinel-2A/B MSIL2A data are proposed for blue and red CCSS material identification, namely the normalized difference blue building index (NDBBI), the normalized difference red building index NDRBI, the enhanced blue building index (EBBI), the enhanced red building index (ERBI), the logical blue building index (LBBI) and the logical red building index (LRBI). These indexes are qualitatively and quantitatively evaluated on a very large number of urban sites all over the P.R. China and compared with the state-of-the-art redness and blueness indexes (RI and BI, respectively). The results demonstrate that the proposed indexes, specifically the LRBI and LBBI, are highly effective in visual evaluation, clearly detecting and discriminating blue and red CCSS covers from other urban materials. Results show that urban areas from the northern parts of P.R. China have larger proportions of blue and red CCSS materials, and areas of blue and red CCSS material buildings are positively correlated with population and urban size at the provincial level across China.

Improvement of the coiling stress calculation model for a mandrel-sleeve-coil

The steel rolling process employs a coiling-uncoiling process in which a steel sheet is wound and unwound in a coil shape using a coiler to efficiently produce a long steel sheet with a constant thickness. As front and rear tension is required when the steel sheet enters and exits the rolling mill, the coiler introduces tension in the steel sheet through the control of the rotational speed. As the coil is produced, coiling tension accumulates, and pressure is applied to the inside of the coil. Finite element analysis and stress calculation analysis were derived from previous studies to prevent such pressure increases in the sleeves and coils. However, the radial and circumferential stresses at arbitrary positions inside the coil cannot be accurately determined by considering without the stresses’ difference in the thickness direction based on the assumption that the coil’s thickness is thin. In this study, an analytical model that can accurately calculate the sleeve and coil stress during elastic deformation was established by improving the internal circumferential stress generated when the steel sheet is bent into a coil and the radial stress equation associated with the beam bending theory. In addition, by comparing the finite element analysis model results reflecting the same coiling condition, this model’s validity was verified by confirming the consistency of the results.

Study of the anisotropy of carbon steel sheet by the tensile test

In test laboratories, the characteristics of the sheets shall be determined by the tensile test on specimens taken in the direction perpendicular to the rolling direction, and these characteristics shall be used as the date of entry into the process of calculating the parts made of the sheet. In the case of parts with special characteristics such as safety parts in the automotive industry, or for mechanically stressed parts in a certain direction, it is important to know precisely the values of the mechanical characteristics of the sheet in relation to the rolling direction, so as to ensure the required resistance. Also, in the case of stamped parts, their quality is all the better the lower the anisotropy. The paper presents the results of experimental research on the mechanical characteristics of the sheet DC04 with a thickness of 0,65 mm, determined by tensile testing on sets of 7 test specimens, taken every 15 degrees from the rolling direction.