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Xuejing Zhang,Junhu Yang,Wenkai Bei,Wei Han,Canyang Chen,Le Yang 한국유체기계학회 2021 International journal of fluid machinery and syste Vol.14 No.2
The efficiency of multiphase twin-screw pump decreases sharply under wet gas conditions (GVF>95%) with severe vibration and thermal problems. Based on the design characteristics of twin-screw pump and screw compressor, a design method of multigradient variable pitch decompression screw pump is to address these problems in this paper. This method keeps the cross section profiles of screw pump unchanged,only changes the pitch of screw. According to the design concept of decompression of screw compressor, the screw rotor is divided into three regions from the inlet to the outlet. The pitch of screw and thread width in these regions are designed separately to increase the volumetric efficiency of the screw pump and reduce the vibration. The effective clearance leakage model of twin-screw pump is simplified and modified. Considering two-phase back flow and combining mechanical model with thermodynamic model, the flow capacity, volumetric efficiency, pressure, and temperature distribution of new and conventional screw pumps are predicted by non-isothermal compression model. The calculations show that the design scheme of multi-gradient variable-pitch decompression screw pump can solve the volumetric efficiency and vibration problems under wet gas conditions fundamentally and can significantly reduce the power consumption of screw pump. However, the problem of temperature rise of screw pump still exists. Cooling system for the screw pump should be designed to continuously cool the screw pump.
Lv Tiantong,Chen Zipeng,Wang Dengfeng,Du Xuejing 한국CDE학회 2024 Journal of computational design and engineering Vol.11 No.1
Combined application of steel, aluminum, and carbon fiber reinforcement plastic (CFRP) is the main direction of future lightweight body development. However, the anisotropy and additional lamination design variables of CFRP parts pose significant challenges for the development of multi-material bodies. This study establishes a parametric design method for the variable-thickness lamination scheme based on non-uniform rational B-splines, it can be coupled with existing parametric design methods for structural shapes to formulate a complete parametric design and modeling of CFRP components. On this basis, a homogenized intermediate material property is derived from classic laminate theory by introducing lamination assumptions, it enables a stepwise multi-material body optimization method to solve the challenge that components’ material design variables switching between CFRP and alloy will introduce/eliminate lamination design variables iteratively, posing a great optimization convergence difficulty. The proposed parametric modeling method for CFRP components was validated by experimental tests of a fabricated roof beam, and the proposed optimization method was applied to a vehicle body, achieving 15.9%, 23.9%, 18.6%, and 12.2% increase in bending and torsional stiffness and modal frequencies; 20.2%, 9.3%, and 12.7% reduction of weight and peak acceleration in frontal and side collisions. This study enables the forward design of multi-material bodies compatible with CFRP parts.
Zhou Jing,Qiu Xuemei,Chen Xuejing,Ma Sihan,Chen Zhaoyang,Wang Ruzhe,Tian Ying,Jiang Yufan,Fan Li,Wang Jingjie 한국미생물학회 2023 The journal of microbiology Vol.61 No.9
Polycystic ovary syndrome (PCOS) is a common disease of endocrine–metabolic disorder, and its etiology remains largely unknown. The gut microbiota is possibly involved in PCOS, while the association remains unclear. The comprehensive analysis combining gut microbiota with PCOS typical symptoms was performed to analyze the role of gut microbiota in PCOS in this study. The clinical patients and letrozole-induced animal models were determined on PCOS indexes and gut microbiota, and fecal microbiota transplantation (FMT) was conducted. Results indicated that the animal models displayed typical PCOS symptoms, including disordered estrous cycles, elevated testosterone levels, and ovarian morphological change; meanwhile, the symptoms were improved after FMT. Furthermore, the microbial diversity exhibited disordered, and the abundance of the genus Ruminococcus and Lactobacillus showed a consistent trend in PCOS rats and patients. The microbiota diversity and several key genera were restored subjected to FMT, and correlation analysis also supported relevant conclusions. Moreover, LEfSe analysis showed that Gemmiger, Flexispira, and Eubacterium were overrepresented in PCOS groups. Overall, the results indicate the involvement of gut microbiota in PCOS and its possible alleviation of endocrinal and reproductive dysfunctions through several special bacteria taxa, which can function as the biomarker or potential target for diagnosis and treatment. These results can provide the new insights for treatment and prevention strategies of PCOS.