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Summary: We propose a computationally efficient stochastic framework and an associated mathematical formulation to assess the improvement in the vibration response of wind turbines with active structural controllers. Uncertainties in the turbulent wind speed as well as in the structural parameters are considered in the formulation for analyzing the 2 important (rated and cut‐out) wind speed conditions. A multimodal wind turbine model based on a NREL 5‐MW wind turbine model is adopted for analysis, and an active tendon controller is used to develop the stochastic framework. Dynamic interaction between the rotor blades and the supporting tower, as well as the coupling induced by the pretwist of the blades, and a collective pitch controller are considered. A time‐evolving phase spectrum method together with a phase delay spectrum model is used to simulate the stochastic wind field, which is computationally less expensive. The probability density contours and the extreme value distributions of the blade tip displacements with and without the active controller are obtained by the wavelet‐based probability density evolution method, followed by the computation of the corresponding failure probabilities. It is observed that the improvement in reliability and performance of the rotor blades with the controller becomes statistically more effective as the wind speed increases (e.g., significant beneficial effects are noticed from the probability distributions in terms of the spread at the cut‐out wind speed). [ABSTRACT FROM AUTHOR]

The probability density evolution method (PDEM) provides a feasible approach for the dynamic response analysis of nonlinear stochastic structures. The key step in this regard is to solve a generalized density evolution equation (GDEE) in order to establish the probability density function (PDF). Previously, a finite difference method (FDM) has often been resorted to solve the GDEE. However, one may encounter the problem of mesh sensitivity in the application of FDM to the PDEM. To this end, a novel difference-wavelet method that can improve the finite difference result by means of a nonlinear wavelet density estimation method is proposed in the present paper. By exploiting the multi-resolution property of wavelet functions and by choosing the optimal scale at each instant, it is expected that the bothering mesh sensitivity issue in finite difference method can be overcome to some extent and a better probability density result can be obtained. In order to verify the proposed method, a single-degree-of-freedom (SDOF) oscillator and an 8-story frame structure are investigated in detail. The results show the notable superiority of the proposed method to finite difference method. [ABSTRACT FROM AUTHOR]

Background: In recent years, gallstones have become a major condition affecting people's health. Cholecystectomy remains an effective treatment method, but it has large risk factors. It is well known that the hepatoenteric axis plays a key role in gallstone formation, and it is gradually becoming a research focus. Cholesterol homeostasis can be regulated by the liver and intestinal tract in our bodies, and intestinal flora can regulate the digestion and absorption of cholesterol. These two factors are closely related to the formation of gallstones. Aim: To investigate the effects of tauroursodeoxycholic acid (TUDCA) and/or intestinal probiotics on serum biochemical indexes and bile composition in patients with cholecystolithiasis. Methods: For this study, 96 patients with cholecystolithiasis were recruited at our hospital. The patients were randomly divided into four groups according to a random number table: group Ⅰ (TUDCA, 24 cases), group Ⅱ (intestinal probiotics, 24 cases), group Ⅲ (TUDCA and intestinal probiotics, 24 cases) and group Ⅳ (control group, 24 cases). All patients underwent laparoscopic gallbladder-preserving lithotomy or laparoscopic cholecystectomy. Bile samples were identified and extracted during the operation. Results: The results revealed that the levels of serum total bile acid (TBA), serum total cholesterol (TCHOL) and serum triglyceride in groups I, II and III before and after the intervention were statistically significant ( p < 0.05). There were significant differences in serum low-density lipoprotein cholesterol (LDL-C) between groups I and II before and after the intervention ( p < 0.05), but the serum LDL-C level in group Ⅲ before and after the intervention was similar ( p > 0.05). Regarding bile, TBA levels demonstrated no significant difference between groups I and III ( p > 0.05), and the differences between the other two groups were statistically significant ( p < 0.05). No significant difference was identified in phospholipid and TCHOL levels between groups I and Ⅲ ( p > 0.05), and the differences between the other two groups were statistically significant ( p < 0.05). There were significant differences in the levels of free Ca 2+ , pH value and glycoprotein in bile among the four groups ( p < 0.05). The levels of cholic acid, chenodeoxycholic acid and deoxycholic acid in bile were significantly different among the four groups ( p < 0.05). The level of lithocholic acid (LCA) in groups Ⅱ and Ⅲ was similar, as was the level of LCA in groups I and ⅠV, but the difference in level between the other two groups was statistically significant ( p < 0.05). Conclusion: The combination of TUDCA and intestinal probiotics did not enhance the effect of either treatment. The use of intestinal probiotics alone can maximise the reverse development of bile composition in patients with cholecystolithiasis compared with TUDCA alone and a combination of TUDCA and intestinal probiotics, thereby reducing gallstone formation., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Gao, Guan, Wang, Zhang, He, Lv, Zhang, Tao, Dai, Xu, Chen and Lu.)