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101.
102.
A multiphase second-order moment turbulent model was developed including an improved closure Reynolds stress transport to describe effectively the anisotropic characteristics of bubble-liquid turbulent flow. The two-phase hydrodynamics in a bubble column were numerically simulated by an in-house code. The effect of the amount of jetting holes on bubble-liquid hydrodynamics in relationship with a cell culture was investigated. Firstly, the bubble energy production correlation was proposed to verify the higher cell damage rate near gas inlet regions. The larger amounts of jetting holes resulted in an increase of bubble stress, bubble kinetic energy, and energy dissipation, particularly bubble energy production at the near gas inlet, which boosted cell damage. 相似文献
103.
通过分析整圆形薄壁支撑零件结构和成形工艺难点,设计了合理的多工位级进模结构,得到了相关成形结构尺寸经验数据。模具加工精度高、产品质量稳定,对同类产品的模具设计有一定的指导意义。 相似文献
104.
Adam Kokotkiewicz Maria Luczkiewicz Pawel Sowinski Daniel Glod Krzysztof Gorynski Adam Bucinski 《Food chemistry》2012
In the presented work, an insight was made into the polyphenolic composition of intact plant material and in vitro cultures of indigenous South African plant Cyclopia subternata Vogel (honeybush). Ethyl acetate fractions of methanol extracts were separated by means of gravity column chromatography and/or semipreparative HPLC on two serially connected monolithic RP-18 columns. The structures of the isolated compounds were determined by means of 1D and 2D NMR techniques and additionally confirmed by LC-DAD-ESI-MS. Apart from the previously described honeybush components, that is mangiferin (1), scolymoside (2), hesperidin (3) and narirutin (4), three additional compounds: iriflophenone 3-C-β-glucoside (benzophenone) (5), phloretin 3′,5′-di-C-β-glucoside (dihydrochalcone) (6), and isorhoifolin (flavone) (7) were identified for the first time in the herb of C. subternata. Additionally, three isoflavone glucosides, namely calycosin 7-O-β-glucoside (8), rothindin (9) and ononin (10), which had not been previously reported in Cyclopia plants, were identified in the callus of the above species. As far as the authors are concerned, this is the first report on the presence of benzophenone and dihydrochalcone derivatives in Cyclopia genus. 相似文献
105.
The effect of addition of electrolytes on gas hold-up of air/water system was investigated experimentally in a laboratory scale bubble column. The experiments were carried out with four electrolytes, namely, NaCl, MgSO4·7H2O, Na2SO4 and CaCl2·2H2O and the concentrations of the solutions were varied from 0 to 0.3 mol/l. Enhancement of gas hold-up was observed for all four electrolytes at concentrations less than 0.1 mol/l. With the increase in concentration, the gas hold-up showed two different trends; in Na2SO4 and CaCl2·2H2O solutions, gas hold-up formed a sharp peak after the enhancement and leveled off at a value somewhat higher than that in water, whereas in NaCl and MgSO4·7H2O solutions, gas hold-up leveled off immediately after the enhancement without forming any peak. Experiments were also conducted to measure the surface tensions of the solutions with special focus in the low concentration region. A strong relation between the gas hold-up enhancement and the change of surface tension with the addition of electrolyte was found. It was also observed that the concentration at which maximum value of C(dσ/dC)2 i.e. (concentration × surface tension gradient with respect to concentration2) is obtained corresponds to the concentration at which maximum gas hold-up enhancement occurs. 相似文献
106.
Xuefeng Su 《Chemical engineering science》2006,61(10):3098-3104
Three bubble column diameters (D=10.2, 15.2, and 32.1 cm) are employed to study the scale-up effect on gas holdup in air-water and air-water-cellulose fiber (hardwood, softwood, and BCTMP) systems. The effect of column diameter depends on flow regime and fiber mass fraction. When , gas holdup decreases with increasing column diameter for the transitional and heterogeneous flow regime, and column diameter effects are negligible in the homogeneous flow regime. When , gas holdup is only affected by column diameter in the transitional flow regime for an air-water system and low fiber mass fraction suspensions (C?0.25%); column diameter effects disappear at medium fiber mass fractions (e.g., C=0.8%) but are significant at high fiber mass fractions (e.g., C=1.4%). 相似文献
107.
Finite-element (FE) simulations are increasingly providing a versatile environment for conducting lateral ground deformation studies. In this environment, mitigation strategies may be assessed in order to achieve economical and effective solutions. On the basis of a systematic parametric study, three-dimensional FE simulations are conducted to evaluate mitigation by the stone column (SC) and the pile-pinning approaches. Mildly sloping saturated cohesionless strata are investigated under the action of an applied earthquake excitation. For that purpose, the open-source computational platform OpenSees is employed, through a robust user interface that simplifies the effort-intensive pre- and postprocessing phases. The extent of deployed remediation and effect of the installed SC permeability are investigated. The influence of mesh resolution is also addressed. Generally, SC remediation was found to be effective in reducing the sand stratum lateral deformation. For a similar stratum with permeability in the silt range, SC remediation was highly ineffective. In contrast, pile pinning appeared to be equally effective for the sand and silt strata permeability scenarios. Overall, the conducted study highlights the potential of computations for providing insights toward the process of defining a reliable remediation solution. 相似文献
108.
苏宜根 《徐州建筑职业技术学院学报》2009,9(3):15-18
基于实际工程,阐述分析了H型薄型变异钢拱架施工工程的安装工艺、吊装方案优选和验算以及支撑胎架设计与主要连接节点的施工. 相似文献
109.
A set of column-footing subassemblies were prepared to investigate construction feasibility and seismic performance of structural joints for concrete-filled fiber reinforced polymer (FRP) tubes (CFFT) as bridge substructure. Based on the common practices of the precast industry and previous research on CFFT, the test matrix included a control reinforced concrete (RC) column and three CFFT columns, all with similar RC footings. The three CFFT columns included a cast-in-place CFFT column with starter bars, a precast CFFT column with grouted starter bars, and a precast CFFT column with unbonded posttensioned rods. The columns were subjected to a constant axial load and a pseudostatic lateral load. All proposed joints proved feasible in construction and robust under extreme load conditions. FRP tube, when secured properly in the footing, showed great influence on the seismic performance of the column by providing both longitudinal reinforcement and hoop confinement to the core concrete. The CFFT columns exhibited significant improvement over traditional RC columns in both ultimate strength and ductility. The study also showed that practices of the precast concrete industry can be easily and effectively implemented for the CFFT column construction. 相似文献
110.
Comparative study of analytical and numerical algorithms for designing reinforced concrete sections under biaxial bending 总被引:1,自引:0,他引:1
This paper presents a comparative study of different integration methods of stresses (both analytical and numerical) for concrete sections subjected to axial loads and biaxial bending. Such methods are applied to circular and rectangular sections. The constitutive equation used is a parabola-rectangle from the Eurocode-2. The comparison was performed with regard to the accuracy and the computational speed of each method. The objective of the paper is to determine which of the integration methods compared is more efficient in computing the interaction surfaces for rectangular and circular sections. The analytical method proposed by Barros et al. [Barros MHFM, Barros A, Ferreira C. Closed form solution of optimal design of rectangular reinforced concrete sections. Eng Comput 2004;21(7):761–76] for rectangular sections is compared with the numerical method termed “modified thick layer integration” proposed by Bonet et al. [Bonet JL, Romero ML, Miguel PF, Fernandez MA. A fast stress integration algorithm for reinforced concrete sections with axial loads and biaxial bending. Comput Struct 2004;82(2–3):213–25] and with the well-known fiber method. Furthermore, two new methods are proposed for circular sections: one analytical and one numerical based on the Gauss–Legendre quadrature. The results of both methods are compared with the classical layer decomposition method. 相似文献