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Scale Effect of the Model Extent on Seepage Analysis of Circular Tunnels under Drained Conditions
Jian Wu,Zhifang Zhou 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.12
Numerical simulations have been widely used to predict groundwater inflow into tunnels during excavations. An appropriate geometric size of a numerical model is crucial for reducing the simulation time and ensuring the accuracy of numerical results. However, to the best of our knowledge, no information concerning the scale effect of the model extent on the seepage characteristics of tunnels under drained conditions has been published. This study evaluates how the model extent affects the tunnel inflow, drawdown, and water pressure via the Signorini type variational inequality formulation. A series of two-dimensional finite element models are conducted with various combinations of tunnel parameters, including tunnel radius, initial groundwater level, lining thickness, and relative permeability. Subsequently, a comprehensive function to yield the optimum model extent within an allowable error is proposed. Interestingly, the optimum model extent for both tunnel inflow and water pressure decreases with an increase in the relative permeability, whereas that of the drawdown exhibits the opposite pattern. A model extent of no less than 200 times the tunnel radius is recommended to acquire accurate model results and is verified with existing analytical methods. This study therefore not only highlights the drainage effect of the tunnel but also provides universal suggestions for engineering practice.
Yunfeng Dai,Zhifang Zhou 한국지질과학협의회 2015 Geosciences Journal Vol.19 No.2
To analyze the seepage characteristics of water-sealed underground oil storage caverns, a calculation software was programmed based on the Signorini type variational inequality formulation. The storage region and boundary condition of oil-groundwater contact surface were generalized, and a two-dimensional numerical simulation model of finite-element method was built. The seepage characteristics and the water inflow of oil storage caverns were analyzed, while the conditions of different oil levels in caverns with water curtain system were taken into account. The effect of a water curtain system was assessed, and the design parameters of water curtain system such as width, water pressure, borehole space, and elevation were evaluated. The seepage simulation model was applied to estimate the seepage field and water inflow of the Huangdao underground oil storage caverns during the future operation period.
Wei Qu,Yabin Zhou,Yundong Sun,Ming Fang,Han Yu,Wenjuan Li,Zhifang Liu,Jiping Zeng,Chunyan Chen,Chengjiang Gao,Jihui Jia 한국미생물학회 2011 The journal of microbiology Vol.49 No.2
Innate and adaptive immune responses are activated in humans when Helicobacter pylori invades the gastric mucosa. Nitric oxide (NO) and reactive nitrogen species are important immune effectors, which can exert their functions through oxidation and S-nitrosylation of proteins. S-nitrosoglutathione and sodium nitroprusside were used as NO donors and H. pylori cells were incubated with these compounds to analyze the inhibitory effect of NO. The suppressing effect of NO on H. pylori has been shown in vitro. Furthermore,the proteins modified by S-nitrosylation in H. pylori were identified through the biotin switch method in association with matrix-assisted laser desorption ionization/time-of-flight tandem mass spectrometry (MALDITOF-MS/MS). Five S-nitrosylated proteins identified were a chaperone and heat-shock protein (GroEL),alkyl hydroperoxide reductase (TsaA), urease alpha subunit (UreA), HP0721, and HP0129. Importantly,S-nitrosylation of TsaA and UreA were confirmed using purified recombinant proteins. Considering the importance of these enzymes in antioxidant defenses, adherence, and colonization, NO may exert its antibacterial actions by targeting enzymes through S-nitrosylation. Identification of protein S-nitrosylation may contribute to an understanding of the antibacterial actions of NO. Our findings provide an insight into potential targets for the development of novel therapeutic agents against H. pylori infection.
Simotang Alleviates the Gastrointestinal Side Effects of Chemotherapy by Altering Gut Microbiota
( Lijing Deng ),( Xingyi Zhou ),( Zhifang Lan ),( Kairui Tang ),( Xiaoxu Zhu ),( Xiaowei Mo ),( Zongyao Zhao ),( Zhiqiang Zhao ),( Mansi Wu ) 한국미생물생명공학회 2022 Journal of microbiology and biotechnology Vol.32 No.4
Simotang oral liquid (SMT) is a traditional Chinese medicine (TCM) consisting of four natural plants and is used to alleviate gastrointestinal side effects after chemotherapy and functional dyspepsia (FD). However, the mechanism by which SMT helps cure these gastrointestinal diseases is still unknown. Here, we discovered that SMT could alleviate gastrointestinal side effects after chemotherapy by altering gut microbiota. C57BL/6J mice were treated with cisplatin (DDP) and SMT, and biological samples were collected. Pathological changes in the small intestine were observed, and the intestinal injury score was assessed. The expression levels of the inflammatory factors IL-1β and IL-6 and the adhesive factors Occludin and ZO-1 in mouse blood or small intestine tissue were also detected. Moreover, the gut microbiota was analyzed by high-throughput sequencing of 16S rRNA amplicons. SMT was found to effectively reduce gastrointestinal mucositis after DDP injection, which lowered inflammation and tightened the intestinal epithelial cells. Gut microbiota analysis showed that the abundance of the anti-inflammatory microbiota was downregulated and that the inflammatory microbiota was upregulated in DDP-treated mice. SMT upregulated antiinflammatory and anticancer microbiota abundance, while the inflammatory microbiota was downregulated. An antibiotic cocktail (ABX) was also used to delete mice gut microbiota to test the importance of gut microbiota, and we found that SMT could not alleviate gastrointestinal mucositis after DDP injection, showing that gut microbiota might be an important mediator of SMT treatment. Our study provides evidence that SMT might moderate gastrointestinal mucositis after chemotherapy by altering gut microbiota.
Zero-Voltage and Zero-Current Switching Interleaved Two-Switch Forward Converter
Chu, Enhui,Bao, Jianqun,Song, Qi,Zhang, Yang,Xie, Haolin,Chen, Zhifang,Zhou, Yue The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.6
In this paper, a novel zero-voltage and zero-current switching (ZVZCS) interleaved two switch forward converter is proposed. By using a coupled-inductor-type smoothing filter, a snubber capacitor, the parallel capacitance of the leading switches and the transformer parasitic inductance, the proposed converter can realize soft-switching for the main power switches. This converter can effectively reduce the primary circulating current loss by using the coupled inductor and the snubber capacitor. Furthermore, this converter can reduce the reverse recovery loss, parasitic ringing and transient voltage stress in the secondary rectifier diodes caused by the leakage inductors of the transformer and the coupled inductance. The operation principle and steady state characteristics of the converter are analyzed according to the equivalent circuits in different operation modes. The practical effectiveness of the proposed converter was is illustrated by simulation and experimental results via a 500W, 100 kHz prototype using the power MOSFET.
Zero-Voltage and Zero-Current Switching Interleaved Two-Switch Forward Converter
Enhui Chu,Jianqun Bao,Qi Song,Yang Zhang,Haolin Xie,Zhifang Chen,Yue Zhou 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.6
In this paper, a novel zero-voltage and zero-current switching (ZVZCS) interleaved two switch forward converter is proposed. By using a coupled-inductor-type smoothing filter, a snubber capacitor, the parallel capacitance of the leading switches and the transformer parasitic inductance, the proposed converter can realize soft-switching for the main power switches. This converter can effectively reduce the primary circulating current loss by using the coupled inductor and the snubber capacitor. Furthermore, this converter can reduce the reverse recovery loss, parasitic ringing and transient voltage stress in the secondary rectifier diodes caused by the leakage inductors of the transformer and the coupled inductance. The operation principle and steady state characteristics of the converter are analyzed according to the equivalent circuits in different operation modes. The practical effectiveness of the proposed converter was is illustrated by simulation and experimental results via a 500W, 100 kHz prototype using the power MOSFET.