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71.
Da SHU Baode SUN Ke LI Jun WANG Yaohe ZHOUState Key Laboratory of Metal Matrix Composites Shanghai Jiao Tong University Shanghai China 《材料科学技术学报》2003,19(3):221-225
The continuous separation of inclusions from aluminum melt flowing in a circular pipe using a high frequency magneticfield was investigated both theoretically and experimentally The separation efficiency was calculated based on thetrajectory method and compared with experimental results. It is found that the separation efficiency is a functilnondimensional parameters t_i·d_p~2B_e~2/μ_fμ_eα~2 and α/δ.The effective way to improve the separation efficiency is to increasethe effective magnetic flux density and decrease the pipe radius. and the value of α/δ should be kept about 2 in orderto obtain the optimum separation efficiency. 相似文献
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75.
Suitability of sweet sorghum in Greece, where irrigation supply during crop development is limited as rainfall is scarce and
evapotranspiration loss is high, is examined in relation with radiation availability. A two-year field experiment was conducted,
in central Greece, imposing four soil water regimes via different irrigation treatments: (1) Highly irrigated, (2) Highly
irrigated till anthesis when irrigation stopped, (3) Medium irrigated, and (4) Low irrigated. It was found that above-ground
dry biomass production from non-water-stressed sweet sorghum plants suggests a high productivity potential among C4 crops. Under water shortage, radiation use efficiency may be significantly lower. Radiation use efficiency seems to be linearly
related to water consumption. Stressed plants (probably except severely stressed) seem to use available water more efficiently
than unstressed plants. The slope of the line relating dry matter produced and water evapotranspired increases the sooner
the stress is sensed. Yield reduction resulting from post-anthesis irrigation stopage is very little. High water use efficiency
values tend to be related with low radiation use efficiency values. 相似文献
76.
建立了热采注汽系统热效率的计算模型。根据XX油田数据计算了2个注汽系统的热效率。提出了提高注汽系统热效率的三项措施:(1)降低锅炉的过剩空气系数;(2)按最大允许热损失设计地面输汽管线的保温层厚度;(3)使用视导热系数小的隔热油管,按箍增加隔热结构,防止热封隔器的泄漏等。 相似文献
77.
The smooth fractionator 总被引:8,自引:0,他引:8
H. J. G. Gundersen 《Journal of microscopy》2002,207(3):191-210
A modification of the general fractionator sampling technique called the smooth fractionator is presented. It may be used in almost every situation in which sampling is performed from distinct items that are uniquely defined, often they are physically separated items or clusters like pieces, blocks, slabs, sections, etc. To each item is associated a ‘guesstimate’ or an associated variable with a more‐or‐less close – and possibly biased ? relationship to the content of the item. The smooth fractionator is systematic sampling among the items arranged according to the guesstimates in a unique, symmetric sequence with one peak and minimal jumps. The smooth fractionator is both very simple to implement and so efficient that it should probably always be used unless the natural sequence of the sampling items is equally smooth. So far, there is no theory for the prediction of the efficiency of smooth fractionator designs in general, and their properties are therefore illustrated with a range of real and simulated examples. At the cost of a slightly more elaborate sampling scheme, it is, however, always possible to obtain an unbiased estimate of the real precision and of some of the variance components. The only real practical problem for always obtaining a high precision with the smooth fractionator is specimen inhomogeneity, but that is detectable at almost no extra cost. With careful designs and for sample sizes of about 10, the sampling variation for the primary, smooth fractionator sampling step may in practice often be small enough to be ignored. 相似文献
78.
The equations for predicting the number-average molecular weight are derived on the basis of the three stage polymerization model (TSPM) in this paper. By applying the equations, a plotting approach is proposed to determine the apparent initiator efficiency defined as f[(αtd+1)/2] and the constant of chain transfer to monomer, where f is the initiator efficiency and αtd denotes the fraction of the termination rate constants by disproportionation. Using the approach to plot the experimental data in the literature, it is found that the chain transfer to monomer can be neglected for both methylmethacrylate (MMA) and styrene (St) polymerizations, but it can exert a significant effect on ethylmethacrylate (EMA) polymerization. In addition, the apparent initiator efficiency is found to be independent of reaction temperature and initiator concentration at each stage. The values of f[(αtd+1)/2] at gel effect stage are slightly reduced as compared with that at low conversion stage for MMA and EMA polymerizations. However, it decreases significantly at gel effect stage for St polymerization. Using the equations derived and the apparent initiator efficiencies obtained from TSPM plots, the number-average molecular weights at different conversions can be predicted. Comparisons show that the agreement between predictions and experimental data is satisfactory. 相似文献
79.
确定异常高压气藏地质储量和可采储量的新方法 总被引:7,自引:1,他引:6
基于文献[1]的定容,封闭,异常高压气藏的物质平衡方程式,提出了确定异常高压气藏原始地质储量,可采储量和采收率的新方法,通过实例的应用和对比表明,提供的新方法是适用的有效的。 相似文献
80.
攀矿选钛厂设计采用传统的螺旋选矿设备FLX一1型φ600mm螺旋选矿机和φ1200mm螺旋溜槽,从选矿(铁)厂磁选尾矿物料中回收原生粒状钛铁矿积累了多年生产实践经验。而广东有色金属研究院研制的GL一2型φ600mm螺旋选矿机具有处理能力大、分选效率高、选别粒级宽、不需冲洗水及占地面积小等特点,有取代选钛厂目前使用的螺旋选矿设备之趋势。 相似文献