http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Simulation of Nonlinear Behavior of Beam Structures Based on Discrete Element Method
Ruo-qiang Feng,Baochen Zhu,Chunchang Hu,Xi Wang 한국강구조학회 2019 International Journal of Steel Structures Vol.19 No.5
In this paper, the discrete element method (DEM) is improved to simulate the strong nonlinear mechanics behavior of beam structures. First, the spring stiff ness of parallel bond model applied to beam structure is deduced using the principle of energy conservation, and the relationship between spring stiff ness and elastic constants is established. Second, the layered beam theory is introduced into the traditional DEM. The yield criteria and the spring stiff ness of contact in yield state are deduced, so that the improved DEM can be used to solve the plastic problem of beam structures. Third, the fracture criterion based on the limit strain of material is defi ned, so that the fracture problem of steel beams can be solved by DEM. Fourth, the force–displacement equations of Hertz model is deduced. Finally, the numerical examples show that the improved DEM can eff ectively solve the problems of large deformation, plasticity, fracture, contact and collision of beam structures.
Numerical simulation of slit wall effect on the Taylor vortex flow with radial temperature gradient
Liu, Dong,Chao, Chang-qing,Zhu, Fang-neng,Han, Xi-qiang,Tang, Cheng Korean Society for Fluid machinery 2015 International journal of fluid machinery and syste Vol.8 No.4
Numerical simulation was applied to investigate the Taylor vortex flow inside the concentric cylinders with a constant radial temperature gradient. The reliability of numerical simulation method was verified by the experimental results of PIV. The radial velocity and temperature distribution in plain and 12-slit model at different axial locations were compared, and the heat flux distributions along the inner cylinder wall at different work conditions were obtained. In the plain model, the average surface heat flux of inner cylinder increased with the inner cylinder rotation speed. In slit model, the slit wall significantly changed the distribution of flow field and temperature in the annulus gap, and the radial flow was strengthen obviously, which promoted the heat transfer process at the same working condition.
Numerical simulation of slit wall effect on the Taylor vortex flow with radial temperature gradient
Dong Liu,Chang-qing Chao,Fang-neng Zhu,Xi-qiang Han,Chengtang Liu 한국유체기계학회 2015 International journal of fluid machinery and syste Vol.8 No.4
Numerical simulation was applied to investigate the Taylor vortex flow inside the concentric cylinders with a constant radial temperature gradient. The reliability of numerical simulation method was verified by the experimental results of PIV. The radial velocity and temperature distribution in plain and 12-slit model at different axial locations were compared, and the heat flux distributions along the inner cylinder wall at different work conditions were obtained. In the plain model, the average surface heat flux of inner cylinder increased with the inner cylinder rotation speed. In slit model, the slit wall significantly changed the distribution of flow field and temperature in the annulus gap, and the radial flow was strengthen obviously , which promoted the heat transfer process at the same working condition.
( Miao Wang ),( Shao Hua Wang ),( Gong Li Zong ),( Zhong Wen Hou ),( Fei Liu ),( D Joshua Liao ),( Xi Qiang Zhu ) 한국미생물 · 생명공학회 2016 Journal of microbiology and biotechnology Vol.26 No.2
Natamycin is a widely used antifungal antibiotic. For natamycin biosynthesis, the gene pimE encodes cholesterol oxidase, which acts as a signalling protein. To confirm the positive effect of the gene pimE on natamycin biosynthesis, an additional copy of the gene pimE was inserted into the genome of Streptomyces gilvosporeus 712 under the control of the ermE* promoter (permE*) using intergeneric conjugation. Overexpression of the target protein engendered 72% and 81% increases in the natamycin production and cell productivity, respectively, compared with the control strain. Further improvement in the antibiotic production was achieved in a 1 L fermenter to 7.0 g/l, which was a 153% improvement after 120 h cultivation. Exconjugants highly expressing pimE and pimM were constructed to investigate the effects of both genes on the increase of natamycin production. However, the co-effect of pimE and pimM did not enhance the antibiotic production obviously, compared with the exconjugants highly expressing pimE only. These results suggest not only a new application of cholesterol oxidase but also a useful strategy to genetically engineer natamycin production.