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71.
材质对蜂窝纸板缓冲性能的影响 总被引:2,自引:1,他引:1
对两种不同材质的蜂窝纸板静态应力应变性能和动态缓冲结果进行了比较分析。讨论了蜂窝纸板力学性能对应变速度的敏感性及两种纸板的缓冲性能差异。缓冲试验结果表明。在不同的冲击应变率下蜂窝纸板的材质影响蜂窝纸板缓冲性能。 相似文献
72.
《Drying Technology》2007,25(5):831-839
Residence time distributions for an aqueous solution of 10% sodium chloride in a spouted bed dryer of inert particles were determined using the stimulus-response technique. Glass and polyethylene beads with diameters 2.6 and 3.4 mm were used as inert bodies in a cylindrical column of 14.0 cm diameter and 60° conical base. The effects of inert bodies load, air, and paste flow rates on the mean residence times and RTD were determined following 23 factorial designs. The RTD could be correlated to the perfect mixing cell model with R2 varying from 0.8684 to 0.9815. The mean residence times in CSBD varied from 10.8 to 13.9 and 10.7 to 13.3 min for glass and polyethylene beads, respectively. For both inert particles, mean residence times increased with bed height and decreased with paste feed rates. Also, terms of interaction among the factors were significant in some cases, showing a complex behavior of paste residence times. Equations obtained by response surface regression could predict mean residence times on glass and polyethylene beads with deviations lower than ±10%. 相似文献
73.
从f(n,t)曲线的研究出发,得到了求解油田单井平均日产油量经济极限值的数学方程式,介绍了用曲线交汇法求解的过程,分析了油田月递减余率和原油销售价是影响油田单井平均日产油量经济极限的主要因素。该方法在油田开发调整方案的编制和油田开发规划部署工作中将起到一定的作用。 相似文献
74.
电子辐照加速器大功率工频高压电源 总被引:1,自引:0,他引:1
文章介绍目前两种用于烟气脱硫加速器的不同形式直流高压电源,分析了它们各自的特点。针对它们存在的不足之处,提出了一种全新的倍压型桥式整流线路,并对此线路进行了理论推导和计算机模拟仿真。 相似文献
75.
《Drying Technology》2007,25(10):1621-1632
A study was performed to determine the drying characteristics and quality of barley grain dried in a laboratory scale spouted-bed dryer at 30, 35, 40, and 45°C and an inlet air velocity of 23 m/s-1, and in an IR-convection dryer under an infrared radiation intensity of 0.048, 0.061, 0.073, and 0.107 W cm-2 at an air velocity of 0.5 m/s-1. The results show that the first, relatively short, phase of a sharp decrease in the drying rate was followed by the phase of a slow decrease. The time of barley drying depended on temperature of inlet air in a spouted-bed dryer and on radiation intensities in an IR-convection dryer. Barley drying at 45°C in a spouted-bed dryer was accompanied by the lowest total energy consumption. The average specific energy consumption was lower and the average efficiency of drying was higher for drying in a spouted-bed dryer. The effective diffusivities were in the range 2.20-4.52 × 10-11 m2 s-1 and 3.04-4.79 × 10-11 m2/s-1 for barley dried in a spouted-bed and in an IR-convection dryer, respectively. There were no significant differences in kernel germination energy and capacity between the two drying methods tested. 相似文献
76.
Polyurethanes were prepared from pure 4,4′-diphenylmethane diisocyanate (MDI), 1,4-butane diol (BDO) or 1,2-ethane diol (EDO) and α,ω-hydroxyl poly(propylene oxide) (PPO) by reaction injection moulding (RIM). Hard segment (MDI + BDO or EDO) level was 45–50 wt%. The PPO had about 20% ethylene oxide copolymerized in at the chain ends to provide 80% primary OH end groups. Mn was varied from 2000 to 4000. Dibutyl tin dilaurate catalyst and mould temperature were varied. Dynamic mechanical, wide-angle X-ray, differential scanning calorimeter, molecular weight and tensile elongation measurements were made on the RIM polyurethanes. At low reaction rates (low catalyst or temperature) highly crystalline, well phase separated but low molecular weight polymers were produced. At high catalyst or temperature levels more poorly phase separated but high molecular weight, tough polymers resulted. Higher Mn PPO gave better phase separation and EDO gave higher melting temperatures. Preventing hard segment crystallinity by substituting asymmetric MDI or glycols resulted in phase compatibility. 相似文献
77.
Wang Xing-kui Li Dan-xun Qu Zhao-song Wang Dian-chang Department of Hydraulic Engineering Tsinghua University Beijing China 《水动力学研究与进展(B辑)》2001,(1)
1 . INTRODUCTIONThebedloadtransporthasbeenextensivelystudiedinthepastfewdecadesandmanyformulasforpredictingbedloadtransportratehavebeenpresented(Einstein 1950 ;Meyer Peter 194 8;Bagnold 1973;Engelund 1976;Yalin 1972 ;Samaga 1986;andKarim 1998) .Whenappliedtostreamswithpartial… 相似文献
78.
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80.
酒泉盆地青西油田快速钻井技术 总被引:3,自引:1,他引:2
酒泉盆地青西地区油层储藏深 ,地层可钻性差 ,钻井过程中存在机械钻速低、井斜不易控制、刺断钻具频繁等问题。为此 ,在近年的钻井实践中 ,采取了优化钻具组合、优选钻头、应用 PDC钻头、强化钻具管理等措施 ,使该区块的钻井速度不断提高 ,钻井周期缩短 ,钻头用量减少 ,从而形成了一套适合该区块的快速钻井技术。 相似文献