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991.
用CCD摄像法测量下喷环流反应器内的气泡行为 总被引:4,自引:0,他引:4
本文开发了一种集高速视频分析系统和计算机数字图像处理技术于一体的具有普适性的动态高速CCD摄像系统,并利用该系统测定了两相三维下喷环流反应气内的环境气泡行为,考察了不同喷咀和操作条件对气泡行为及平均传质比表面积的影响。 相似文献
992.
Preparation of HDPE/SEBS‐g‐MAH and its effect on mechanical properties of HDPE/wood flour composites
In this article, high density polyethylene/styrene‐ethylene‐butylene‐styrene block copolymer blends (HDPE/SEBS) grafted by maleic anhydride (HDPE/SEBS‐g‐MAH), which is an effective compatibilizer for HDPE/wood flour composites was prepared by means of torque rheometer with different contents of maleic anhydride (MAH). The experimental results indicated that MAH indeed grafted on HDPE/SEBS by FTIR analysis and the torque increased with increasing the content of maleic anhydride and dicumyl peroxide (DCP). Styrene may increase the graft reaction rate of MAH and HDPE/SEBS. When HDPE/SEBS MAH was added to HDPE/wood flour composites, tensile strength and flexural strength of composites can reach 25.9 and 34.8 MPa in comparison of 16.5 and 23.8 MPa (without HDPE/SEBS‐g‐MAH), increasing by 157 and 146%, respectively. Due to incorporation of thermoplastic elastomer in HDPE/SEBS‐g‐MAH, the Notched Izod impact strength reached 5.08 kJ m?2, increasing by 145% in comparison of system without compatibilizer. That HDPE/SEBS‐g‐MAH improved the compatibility was also conformed by dynamic mechanical measurement. Scanning electron micrographs provided evidence for strong adhesion between wood flour and HDPE matrix with addition of HDPE/SEBS‐g‐MAH. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 相似文献
993.
Simon Piché 《Chemical engineering science》2005,60(22):6452-6461
The oxidative absorption of hydrogen sulfide (H2S) into a solution of ferric chelate of trans-1,2- diaminocyclohexanetetraacetate (CDTA) was studied in a counter-current laboratory column randomly packed with 15 mm plastic Ralu rings. The present investigation takes concern about the Kraft pulping situation where dilute H2S concentrations are omnipresent in large-volume gas effluents. A fractional two-level factorial approach was instigated to determine the significance of six operating variables, namely the solution's alkalinity (pH; 8.5-10.5), the liquid mass flow rate (L;1.73-), the solution's ionic strength (IC;0.01-), the gas mass flow rate (G;0.19-), the inlet H2S concentration (CH2S,0;70-430 ppm) and the initial ferric CDTA concentration (CFe,0;100 -). Initially, a Plackett-Burman design matrix of seven duplicated experiments revealed that pH is the leading factor controlling the H2S conversion rate while the ionic strength and ferric CDTA concentration effects remained negligible within the factorial domain. Surface response analysis based on 11 duplicated factorial experiments plus 10 central composite trials revealed that the H2S conversion significantly increases with liquid flow rate but decreases with growing H2S load up. Further examination about the influence of ferric CDTA on H2S absorption rate was set up over a broader concentration range (CFe,0;0- at pH of 9.5 and 10.5. It showed good potential at as H2S conversion increased by a significant 25% for both pH values in comparison to pure alkaline solutions containing no ferric CDTA. 相似文献
994.
Guadalupe Del C. Pizarro Oscar G. Marambio Manuel Jeria O Margarita Huerta Bernab L. Rivas 《应用聚合物科学杂志》2006,100(1):178-185
The free‐radical copolymerization of water‐soluble poly(1‐vinyl‐2‐pyrrolidone‐co‐hydroxyethylmethacrylate) was carried out with a feed monomer ratio of 75:25 mol %, and the total monomer concentration was 2.67M. The synthesis of the copolymer was carried out in dioxane at 70°C with benzoyl peroxide as the initiator. The copolymer composition was obtained with elemental analysis and 1H‐NMR spectroscopy. The water‐soluble polymer was characterized with elemental analysis, Fourier transform infrared, 1H‐ and 13C‐NMR spectroscopy, and thermal analysis. Additionally, viscosimetric measurements of the copolymer were performed. The thermal behavior of the copolymer and its complexes were investigated with differential scanning calorimetry (DSC) and thermogravimetry techniques under a nitrogen atmosphere. The copolymer showed high thermal stability and a glass transition in the DSC curves. The separation of various metal ions by the water‐soluble poly(1‐vinyl‐2‐pyrrolidone‐co‐hydroxyethylmethacrylate) reagent in the aqueous phase with liquid‐phase polymer‐based retention was investigated. The method was based on the retention of inorganic ions by this polymer in a membrane filtration cell and subsequent separation of low‐molar‐mass species from the polymer/metal‐ion complex formed. Poly(1‐vinyl‐2‐pyrrolidone‐co‐hydroxyethylmethacrylate) could bind metal ions such as Cr(III), Co(II), Zn(II), Ni(II), Cu(II), Cd(II), and Fe(III) in aqueous solutions at pHs 3, 5, and 7. The retention percentage for all the metal ions in the polymer was increased at pH 7, at which the maximum retention capacity could be observed. The interaction of inorganic ions with the hydrophilic polymer was determined as a function of the pH and filtration factor. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 178–185, 2006 相似文献
995.
Yuji Tatemoto Masaya Tsunekawa Shuji Yano Takenari Takeshita Katsuji Noda 《Chemical engineering science》2007,62(8):2187-2197
A relatively large wet material was immersed in a fluidized bed of hygroscopic porous particle (silica gel beads) under reduced pressure. And then the drying characteristics were compared with those in the case of inert particle (glass beads). The comparison of drying characteristics is performed experimentally and theoretically. In calculation, the water transfer from the sample to the fluidized bed was considered. The calculation results are in good agreement with the experimental data. The effects of the operational conditions (the pressure in the drying chamber and the temperature of the drying gas) on the drying characteristics were also examined in both fluidizing particles.The drying finishes earlier in the case of hygroscopic porous particle than in the case of inert particle regardless of pressure in the drying chamber, since the water transfer from the sample facilitates the drying in the case of hygroscopic porous particles. The temperature decrement in drying appears in the case of inert particle. This phenomenon is also observed in the case of hygroscopic porous particle, but the decrement degree of the temperature is much smaller than that in the case of inert particle. The difference of the minimum temperature in the sample in drying between the cases of hygroscopic porous particle and inert particle is very slight for different pressures in the drying chamber. 相似文献
996.
Rosario?Zamora Gemma?Gómez Francisco?J.?HidalgoEmail author 《Journal of the American Oil Chemists' Society》2002,79(3):267-272
13C NMR spectra of oil fractions obtained chromatographically from 109 vegetable oils were obtained and analyzed to evaluate
the potential use of those fractions in the classification of vegetable oils and to compare the results with the NMR analysis
of complete oils. The oils included the following: virgin olive oils from different cultivars and regions of Europe and north
Africa; “lampante” olive, refined olive, refined olive pomace, hazelnut, rapeseed, high-oleic sunflower, corn, grapeseed,
soybean, and sunflower oils; and mixtures of virgin olive oils from different geographical origins. Oils were divided into
two sets of samples. The training set (98 samples) was employed to select the variables that resulted in significant discrimination
among the different oil classes. By using stepwise discriminant analysis, more than 98% of correct validated assignments were
obtained; these results were confirmed when applied to the test set (11 blind samples). Results suggest that the use of oil
fractions considerably increases the discriminating power of NMR in the analysis of vegetable oils. 相似文献
997.
Response to walnut olfactory and visual cues by the parasitic wasp Diachasmimorpha juglandis 总被引:2,自引:0,他引:2
Diachasmimorpha juglandis is a specialist parasitoid attacking fly larvae in the genus Rhagoletis that feed exclusively on walnut fruit husks. In a free-foraging assay comparing response to uninfested, infested, and mechanically damaged fruits, we first determined that D. juglandis use host feeding damage on the fruit as a cue for host presence. In another free-foraging assay that used artificial walnut models and wind tunnel experiments, D. juglandis distinguished infested from uninfested fruits by using either olfactory or visual cues separately. However, the response rate of wasps in the wind tunnel was raised considerably when visual cues were also available. We analyzed the volatile compounds emitted by cohorts of uninfested, mechanically damaged, and infested fruits 1, 3, 5, 8, and 10 days after oviposition by flies into the infested fruits. Total volatile emissions did not differ significantly among treatments, but quantitative changes in volatiles distinguished infested fruits from uninfested and damaged fruits. The fact that parasitoids did not distinguish between infested and damaged fruits in assays where damage was visible indicates that they rely on visual cues when those are available. 相似文献
998.
用主元分析方法完善DCS过程监控性能 总被引:6,自引:2,他引:6
在分析目前DCS过程监控性能尚存不足的基础上,结合主元分析(PCA)算法,提出了一种用PCA完善DCS过程监控性能的系统结构。该系统包括组态环境与运行环境,其中组态环境完成主元模型的建立与检验、统计量控制限的确定以及统计量监视图的组态等功能;运行环境通过数据库调用组态环境设计的参数来完成实时过程监控。仿真结果表明,该方法能够结合DCS进一步完善系统的过程监控性能。 相似文献
999.
The National Aeronautics and Space Administration's (NASA's) PS304 coating is a plasma spray deposited tribological coating with feedstock composed of NiCr, Cr2O3, Ag and BaF2-CaF2 powders. The effects of rounded BaF2-CaF2 particles on the gravity-fed flow characteristics of PS304 feedstock have been investigated. The BaF2-CaF2 powder was fabricated by water atomization using four sets of process parameters. Each of these powders was then characterized by microscopy and classified by screening to obtain 45-106 μm particles and added incrementally from 0-10 wt.% to the other constituents of the PS304 feedstock, namely nichrome, chromia and silver powders. The relationship between feedstock flow rate, measured with the Hall flowmeter, and concentration of fluorides was found to be linear in each case. The slopes of the lines were between those of the linear relationships previously reported using angular and spherical fluorides and were closer to the relationship predicted using the rule of mixtures. The results offer a fluoride fabrication technique potentially more cost-effective than gas atomization processes or traditional comminution processes. 相似文献
1000.
基于流动平衡的塑料挤出模优化设计 总被引:1,自引:0,他引:1
在构建流道三维参数化模型的基础上,将有限元数值分析和优化技术相结合,以口模出口处型材截面上各子区域平均流速相等为优化目标,以压缩段入口壁厚和平直段长度为设计变量,对挤出模优化设计进行了研究。并以实例说明了优化设计的具体过程,验证了所用方法的正确性和有效性。 相似文献