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991.
TIEFENG WANG JINFU WANG BIN ZHAO FEI REN YONG JIN 《Chemical Engineering Communications》2013,200(8):1024-1042
The hydrodynamic behavior of an external loop airlift slurry reactor (ALSR) with and without a resistance-regulating element was studied with a fiber optic probe and ultrasound Doppler velocimetry. The influences of the superficial gas velocity and solid holdup on the global gas holdup and radial profiles of the suspension circulation velocity in the downer and of gas holdup, bubble size, and bubble rise velocity in the riser were studied. Local measurements allow a better understanding of the flow behavior in the reactor and can be used for CFD modeling and validation. Experimental results show that the resistance-regulating element increases the gas holdup and decreases the suspension circulation velocity, indicating that an optimum design of the flow resistance is needed to obtain the maximum gas-liquid volumetric mass transfer coefficient for a specific superficial gas velocity. A high superficial gas velocity and low solid holdup are favorable for increased uniformity of the radial profile of the gas holdup and bubble rise velocity. Hydrodynamic models that predict the gas holdup and suspension circulation velocity were developed for an ALSR with and without a resistance-regulating element. Good agreement was obtained between measured and predicted values. 相似文献
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993.
An orthogonal test was conducted to investigate the influence of technical parameters of squeeze casting on the strength and ductility of AlSi9Cu3 alloys. The experimental results showed that when the forming pressure was higher than 65 MPa, the strength (σb) of AlSi9Cu3 alloys decreased with the forming pressure and pouring temperature increasing, whereas σb increased with the increase of filling velocity and mould preheating temperature. The ductility (δ) by alloy was improved by increasing the forming pressure and filling velocity, but decreased with pouring temperature increasing. When the mould preheating temperature increased, the ductility increased first, and then decreased. Under the optimized parameters of pouring temperature 730 °C, forming pressure 75 MPa, filling velocity 0.50 m/s, and mould preheating temperature 220 °C, the tensile strength, elongation, and hardness of AlSi9Cu3 alloys obtained in squeeze casting were improved by 16.7%, 9.1%, and 10.1%, respectively, as compared with those of sand castings. 相似文献
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997.
Predictive Microbiology for Monitoring Spoilage of Dairy Products with Time-Temperature Integrators 总被引:6,自引:0,他引:6
Time/temperature integrators (TTI) have a potential for monitoring time-temperature history of perishable foods, including dairy products. To correlate the end of shelf life of dairy products with different TTI's, kinetic data for growth of a dairy spoilage microorganism was obtained. Both Arrhenius and square root equations were used to model the growth of Pseudomonas fragi. A significant negative history effect was observed for P. fragi growth rate whereas history effect was positive on the lag phase, under certain nonisothermal conditions. A correlation scheme of P. fragi growth was developed with the TTI response. The application of TTI's for dairy products is feasible despite the history effects. 相似文献
998.
该回路有多个环形管系、布置紧凑、运行温度高。原设计未考虑支撑,因此“安全问题”比较突出。根据SDGJ6-78规定。利用PSDP程序,对此回路进行了一次、二次或一次加二次应力验算,改进了原设计,并对支撑作了合理布置。计算表明在给定条件下运行是安全的。 相似文献
999.
本文从像面光场移动的观点对一步无狭缝彩虹全息术中平移物体和透镜形成的综合狭缝进行了理论分析,并提出了一种新的综合狭缝二步彩虹全息方法. 相似文献
1000.
曹宏 《武汉理工大学学报(材料科学英文版)》2007,22(2):214-217
The graphite encapsulatedα-Fe particles were prepared by reduction of stage-2 and stage-3 FeCl 3 graphite intercalation compounds(GICs)with metallic potassium.X-ray diffraction analysis(XRD),energy dispersive X-ray spectroscopy(EDS)investigation and transmission electron microscopy(TEM) observation show that the reduction products of stage-2 FeCl 3 -GICs contains more abundantα-Fe nanoparticles than those of stage-3.High-resolution TEM(HRTEM)observation reveals that the nanoparticle ofα-Fe was polycrystals or twins,which was real or quasi two-dimension in shape,and whose space orientation was strictly controlled by the graphene.Based on the experiment results,a possible growth model of the graphite encapsulatedα-Fe was proposed. 相似文献