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The COVID-19 pandemic has had a profound impact on human society. The isolation of SARS-CoV-2 from patients' feces on human cell line raised concerns of possible transmission through human feces including exposure to aerosols generated by toilet flushing and through the indoor drainage system. Currently, routes of transmission, other than the close contact droplet transmission, are still not well understood. A quantitative microbial risk assessment was conducted to estimate the health risks associated with two aerosol exposure scenarios: 1) toilet flushing, and 2) faulty connection of a floor drain with the building's main sewer pipe. SARS-CoV-2 data were collected from the emerging literature. The infectivity of the virus in feces was estimated based on a range of assumption between viral genome equivalence and infectious unit. The human exposure dose was calculated using Monte Carlo simulation of viral concentrations in aerosols under each scenario and human breathing rates. The probability of COVID-19 illness was generated using the dose-response model for SARS-CoV-1, a close relative of SARS-CoV-2, that was responsible for the SARS outbreak in 2003. The results indicate the median risks of developing COVID-19 for a single day exposure is 1.11 × 10-10 and 3.52 × 10-11 for toilet flushing and faulty drain scenario, respectively. The worst case scenario predicted the high end of COVID-19 risk for the toilet flushing scenario was 5.78 × 10-4 (at 95th percentile). The infectious viral loads in human feces are the most sensitive input parameter and contribute significantly to model uncertainty.

Oil extraction is shifting towards high-temperature and high-pressure environments, which leads to the deterioration of the rubber material used in packer rubber cylinders, ultimately resulting in sealing failure. Hence, we propose enhancing the configuration of the rubber cylinder by incorporating a composite material consisting of metal and rubber. Additionally, we suggest integrating springs at the shoulders to fabricate a spring-embedded shoulder protection packer rubber cylinder. ABAQUS 2023 software was employed to simulate the packer setting process, investigating the variations in compression distance between a conventional packer rubber cylinder and a spring-embedded shoulder protection packer rubber cylinder. The results showed that at 25 °C and 177 °C, the compression distance of the fully seated spring-embedded shoulder protection packer rubber cylinder was reduced by 3% compared to the traditional packer rubber, Mises stress was reduced by 14%, and the sealing performance evaluation coefficient K of the rubber cylinder was increased by 2% to 10%.The stress in the spring-embedded shoulder protection packer rubber cylinder is primarily concentrated between the spring and the wire mesh, effectively ensuring the performance of the rubber cylinder and mitigating any potential decrease in sealing performance caused by internal stress concentration. The spring-embedded protective rubber cylinder will not experience shoulder protrusion during the sealing process. The incorporation of a spring-embedded shoulder protection mechanism in the packer rubber cylinder enhances the contact stress between the rubber cylinder and casing tube, mitigates stress concentration within the rubber cylinder, resolves shoulder protrusion issues, and ultimately improves both sealing performance and service life. [ABSTRACT FROM AUTHOR]