When designing, constructing and operating sewage pipelines in high-rise buildings, issues of failure-free operation of a network arise. Investigation of the processes of wastewater moving allows identifying problem areas during operation, assessing the possibility of obstructions and breakdowns of plumbing traps on the gravity drainage sections of the pipeline. The article performs the schemes of the water outflow from the floor sewer into the riser, including the places where the riser is bent, of air delivery to the working riser under the change of the direction of drain movement with the dropout line set-up, with the installation of an automatic anti-vacuum valve, with the installation of the ventilation pipeline. Investigations of the process of sewage waste flow in a sewage riser were carried out, in order to select the appropriate structure. The authors consider structure features of some sections of sewerage in high-rise buildings. The exhaustion value in the riser is determined from the rarefactions that occur below the compressed cross-section of the riser and the loss of the air flow pressure coming from the atmosphere into the riser during the deflooding of the liquid. Preventing the formation of obstructions and breakdowns of plumbing traps is an integral part of sewage networks.

The paper presents the results of the study in the field of ensuring the business stability of industrial and energy enterprises by determining the influence of external and internal factors. Identification of stability criteria was carried out by an expert survey using a simple but reliable mathematical apparatus. The final integral indicator of the economic stability of an industrial enterprise was obtained by a calculation and expert method using economic and mathematical modeling. The proposed method is quite universal and can be used to assess the stability of an enterprise over time, as well as to compare the stability of several enterprises with each other.

Smart city technologies make the functioning of urban infrastructure more efficient, and the lives of citizens more comfortable and safe. During the COVID-19 pandemic, they were very popular, and this could not but affect the energy efficiency of high-tech megacities around the world. This article examines the impact of the COVID-19 pandemic on smart cities, and also offers a solution to the problem of energy efficiency of smart cities.