Axial dynamic load identification of hydraulic turbine based on Chebyshev orthogonal polynomial approximation

An analysis method is proposed to identify axial dynamic loads acting on the Francis turbine based on Chebyshev orthogonal polynomial expansion theory. Dynamic loads are expressed as functions of time and polynomial coefficients. The dynamic load identification model is constructed through discretized integral convolution of the loads, such as the Duhamel integral. However, the discretized numerical integral has a time-cumulative error problem that decreases the recognition accuracy of the dynamic load. Compared with the traditional method, the algorithm proposed in this paper constructs the relationship between the modal displacement and force using polynomial orthogonality and derivative relation between displacement and velocity or acceleration. The new method could avoid the Duhamel integral and time-cumulative error problem. This algorithm not only requires less measuring point information, but is also highly efficient. Compared with genetic algorithm identification, orthogonal polynomial algorithm is not easy falling into local convergence, and does not require multiple repetitions positive analysis trial to evaluate individual fitness value. Numerical simulations demonstrate that the identification and assessment of dynamic loads are effective and consistent when the proposed method is used

The Resistance of Ship Web Girders in Collision and Grounding

Ship web girders play an important role in ship structure performance during collision and grounding accidents. The behavior of web girders subjected to in-plane concentrated load is investigated by numerical simulation and theoretical analysis in this paper. A numerical simulation based on previous experiment is conducted to give insight to the deformation mechanism of crushing web girders. Some new important deformation characteristics are observed through the simulation results. A new theoretical deformation model is proposed featured with these deformation characteristics, and a simplified analytical method for predicting the instantaneous and mean resistances of crushing web girders is proposed. The proposed method is verified by two previous experiments and a series of numerical simulations. The agreement between the solutions by the proposed method and the experiment results is good. The comparison results between the proposed analytical method and numerical simulation results are satisfactory for most cases. The proposed analytical method will contribute to the establishment of an efficient method for fast and reliable assessment of the outcome of ship accidental collisions and grounding events

Effect of a combination of omeprazole and high-dose proton pump inhibitors on the treatment of patients with liver cirrhosis complicated with upper gastrointestinal hemorrhage

Purpose: To determine the effect of a combination of omeprazole and high-dose proton pump inhibitor (PPI) on the treatment of patients with liver cirrhosis complicated with upper gastrointestinal hemorrhage.Methods: A total of 100 patients with liver cirrhosis and upper gastrointestinal hemorrhage who were admitted to Qingdao Chengyang District People’s Hospital from January 2019 to September 2020 were matched and randomly assigned to a control group and a study group. Patients in both groups received a high-dose PPI treatment, while those in the study group were given omeprazole in addition to highdose PPI. Total treatment effectiveness, incidence of adverse reactions, bleeding volume, hemostasis time, liver function after treatment, Quality of Life Index (QLI) scores, Visual Analogue Scale (VAS) scores, and bleeding (%) at 1, 2 and 4 weeks after treatment were compared for the two groups of patients.Results: Omeprazole-PPI combination produced a much more favorable outcome than treatment with only high-dose PPI, in terms of effectiveness, QLI scores and liver function (p < 0.05). The study group had significantly lower incidence of adverse reactions, bleeding volume, VAS scores, and degree of bleeding at 1, 2 and 4 weeks after treatment, as well as shorter hemostasis time, than the control group (p < 0.05).Conclusion: A combination treatment of omeprazole and high-dose PPI produces better therapeutic effect than high-dose PPI alone, in patients with liver cirrhosis and upper gastrointestinal hemorrhage

Differentiation of multipotent vascular stem cells contributes to vascular diseases.

It is generally accepted that the de-differentiation of smooth muscle cells, from the contractile to the proliferative/synthetic phenotype, has an important role during vascular remodelling and diseases. Here we provide evidence that challenges this theory. We identify a new type of stem cell in the blood vessel wall, named multipotent vascular stem cells. Multipotent vascular stem cells express markers, including Sox17, Sox10 and S100β, are cloneable, have telomerase activity, and can differentiate into neural cells and mesenchymal stem cell-like cells that subsequently differentiate into smooth muscle cells. On the other hand, we perform lineage tracing with smooth muscle myosin heavy chain as a marker and find that multipotent vascular stem cells and proliferative or synthetic smooth muscle cells do not arise from the de-differentiation of mature smooth muscle cells. In response to vascular injuries, multipotent vascular stem cells, instead of smooth muscle cells, become proliferative, and differentiate into smooth muscle cells and chondrogenic cells, thus contributing to vascular remodelling and neointimal hyperplasia. These findings support a new hypothesis that the differentiation of multipotent vascular stem cells, rather than the de-differentiation of smooth muscle cells, contributes to vascular remodelling and diseases

Ascher syndrome

AbstractAscher syndrome is a rare, benign skin disorder characterized by a double upper lip, blepharochalasis, and nontoxic enlargement of the thyroid gland. The exact cause is unknown, but it is considered to be a hereditary disease with an autosomal dominant trait. We report here a case of forme fruste Ascher syndrome in a 29-year-old man