RESUMO
Ultra-high-performance concrete (UHPC) is a cement-based material with excellent impact resistance. Compared with traditional concrete, it possesses ultra-high strength, ultra-high toughness, and ultra-high durability, making it an ideal material for designing structures with impact resistance. The research on the impact resistance performance of UHPC and its composite structures is of great significance for the structural design of protective engineering projects. However, currently, there is still insufficient research on the impact resistance performance of UHPC composite structures. To study the impact resistance performance, experiments were conducted on UHPC targets using high-speed projectiles. The results were compared with impact tests on granite targets. The results indicated that when subjected to projectile impact, the UHPC targets exhibited smaller surface craters compared with the granite targets, while the penetration depth was lower in the granite targets. Afterwards, the process of a projectile impacting the UHPC composite structure was numerically simulated using ANSYS 16.0/LS-DYNA finite element software. The numerical simulation results of penetration depth and crater diameter were in good agreement with the experimental results, which indicates the rationality of the numerical model. Based on this, further analysis was carried out on the influence of impact velocity, impact angle, and reinforcement ratio on the penetration depth of the composite structure. The results show that the larger the incident angle or the smaller the velocity of the projectile is, the easier it is to deflect the projectile. There is a linear relationship between penetration depth and reinforcement ratio; as the reinforcement ratio increases, the penetration depth decreases significantly. This research is of great significance in improving the safety and reliability of key projects and also contributes to the application and development of ultra-high-performance materials in the engineering field.
RESUMO
Building upon the foundational principles of the grid search algorithm and Monte Carlo numerical simulation, this article introduces an innovative epidemic monitoring and prevention plan. The plan offers the capability to accurately identify the sources of infectious diseases and predict the final scale and duration of the epidemic. The proposed plan is implemented in schools and society, utilizing computer simulation analysis. Through this analysis, the plan enables precise localization of infection sources for various demographic groups, with an error rate of less than 3%. Additionally, the plan allows for the estimation of the epidemic cycle duration, which typically spans around 14 days. Notably, higher population density enhances fault tolerance and prediction accuracy, resulting in smaller errors and more reliable simulation outcomes. Overall, this study provides highly valuable theoretical guidance for effective epidemic prevention and control efforts.
RESUMO
BACKGROUND: Osteoporotic vertebral compression fracture (OVCF) is usually treated by percutaneous kyphoplasty (PKP) which has limitations. We aimed to evaluate the effects of PKP combined with zoledronic acid (ZOL) injection on OVCF and bone metabolism indices. METHODS: A total of 600 OVCF patients admitted from June 2015 to June 2020 were randomly divided into group A (PKP alone), group B (PKP combined with ZOL 1 month later) and group C (PKP concurrently combined with ZOL) (n=200). Before as well as 1 month (before ZOL treatment in group B) and 1 year after PKP, the pain degree, physical function and self-care ability in daily life were assessed, the height and kyphosis Cobb angle of vertebral body with compression fracture and bone mineral densities (BMDs) at different parts were measured, the clinical efficacy, adverse reactions and recurrence of vertebral fractures during 3 years of follow-up were observed, and the serum levels of BAP, BGP, ß-CTx and TP1NP were detected. RESULTS: Compared with groups A and B, group C had significantly reduced visual analogue scale (VAS) and Oswestry disability index (ODI) scores and raised activity of daily living (ADL) score 1 month after PKP (P<0.05). Groups A-C had successively lowered VAS and ODI scores and elevated ADL score 1 year after PKP (P<0.05). Compared with before PKP, the height of vertebral body with compression fracture significantly increased, and the kyphosis Cobb angle decreased in the three groups 1 month and 1 year after PKP (P<0.05). In group A, the height was lower whereas the angle was larger 1 year after PKP than those 1 month after PKP (P<0.05). One month after PKP, the height was significantly higher and the angle was smaller in group C than those of groups A and B (P<0.05). One year after PKP, the height significantly increased and the angle decreased successively in groups A-C (P<0.05). BMDs at different parts were significantly higher in group C than those of groups A and B 1 month after PKP (P<0.05). One year after PKP, BMDs were highest in group C and lowest in group A (P<0.05). The overall response rate was significantly higher in group C than that in group A (P<0.05). The recurrence rate of fractures was significantly higher in group A than those of groups B and C (P<0.05). The BAP, BGP, ß-CTx and TP1NP levels were significantly lower in group C than those of groups A and B 1 month after PKP (P<0.05), and declined successively in groups A-C 1 year after PKP (P<0.05). CONCLUSIONS: PKP concurrently combined with ZOL exert the most significant therapeutic effects on OVCF, with the lowest recurrence rate of fractures. It relieves pain and improves the physical function and self-care ability in daily life probably by reducing bone metabolism indices, increasing BMD, and maintaining the height and kyphosis Cobb angle of recovered vertebral body.