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161.
以船用轴流式喷水推进泵为对象,探索了轴流泵参数化设计、水动力性能、静强度和结构声学特征分析的数值途径。轴流泵叶轮采用升力法设计,导叶采用流线法设计,叶片三维造型在NUMECA参数化设计平台中完成。轴流泵水动力性能校核由粘性CFD计算完成,CFD计算同时提取得到叶片分布式水动力载荷。叶片静强度校核由ANSYS有限元计算叶片应力和应变特征完成,应力分析时同时考虑水动力载荷、重力载荷和离心力载荷。叶片结构声学特征分析由NASTRAN有限元计算叶片模态振型和振型频率完成。计算结果表明,轴流泵扬程和功率满足设计指标,效率达87.13%;叶轮叶片形变相对于叶顶间隙来说为极小量,可忽略不计,叶片存在局部应力集中现象,最大应力小于许用应力,满足静强度要求;叶片前四阶振型特征与分析经验一致,且振型频率远离轴频、叶频及其谐频特征频率,能够避免共振产生。 相似文献
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163.
E. Shumilin St. Kalmykov D. Sapozhnikov E. Nava-Sánchez D. Gorsline L. Godinez-Orta Yu. Sapozhnikov O. Holguin Quiñones A. Rodriguez Castaneda 《Journal of Radioanalytical and Nuclear Chemistry》2000,246(3):533-541
The vertical distribution of K, Rb, Cs, Ca, Sr, Ba, Fe, Cr, Co, Ni, Zn, Sc, Zr, Sb, Se and As was studied by means of instrumental neutron activation analysis in four sediment cores collected from the eastern shelf of tectonically active Baja California peninsula accompanied by 210Pb age-dating. 210Pb analysis was performed by extraction chromatography with measuring the ingrowing daughter 210Bi radioactivity by liquid-scintillation spectrometry. It was found that concentration variations of Se, As, Sb, Zr and Zn are probably controlled by the intensity and composition of the material supplied from the drainage basin constituted by volcanic and sedimentary rocks. 相似文献
164.
In this study, a new process was developed for manganese peroxidase (MnP) production by Phanerochaete chrysosporium under an agitated and aerated cultivation condition. It was found that change of the inoculum from spore suspension to pellets
resulted in enhanced MnP production of 200 U/L in rotated shake flasks. Several additives, including Pluronic F68, Tween 80,
and PEG8000, significantly increased the enzyme production. With an optimal concentration in 125 mL flasks, Pluronic F68 increased
MnP productivity by 180%. Moreover, successful enzyme production was achieved in a 5-L fermentor at an agitation speed of
300 rpm with the addition of 0.1% Pluronic F68. 相似文献
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167.
The convergence of a Neumann-series solution of the Marchenko equation in L
2[x, ∞) is proved and an explicit expression of the series solution is given. 相似文献
168.
陈志敏 《应用数学和力学(英文版)》2012,33(11):1467-1480
A doublet integral equation is formulated for the two-dimensional dissipative potential flow around a hydrofoil submerged below a free-water surface. The free-water surface is assumed to involve energy dissipation, and thus it is the source of damping. A doublet panel method is developed from incorporation of the dissipative Green function approach and the doublet distributions on the hydrofoil surface. Numerical computations are implemented, and the derived numerical results are in good agreement with analytic solutions and experimental measurements. 相似文献
169.
We investigate existence and uniqueness of solutions of a McKean–Vlasov evolution PDE representing the macroscopic behaviour of interacting Fitzhugh–Nagumo neurons. This equation is hypoelliptic, nonlocal and has unbounded coefficients. We prove existence of a solution to the evolution equation and non trivial stationary solutions. Moreover, we demonstrate uniqueness of the stationary solution in the weakly nonlinear regime. Eventually, using a semigroup factorisation method, we show exponential nonlinear stability in the small connectivity regime. 相似文献
170.
Freire F Seco JM Quiñoá E Riguera R 《Chemical communications (Cambridge, England)》2007,(14):1456-1458
The absolute configuration of beta-chiral primary alcohols devoid of observable hydrogens on one of the beta-substituents at the asymmetric carbon (L(1)/L(2)) can be determined by comparison of the (1)H NMR of their (R)- and (S)-9-AMA ester derivatives and analysis of the Deltadelta(RS) for the L substituent and the Cbeta-H. 相似文献