5%乙烯-醋酸乙烯共聚物复合低热水泥浆体的碳化促进养护

采用碳化养护方法促进5%乙烯-醋酸乙烯共聚物复合低热水泥浆体的水化.通过X射线衍射定性及定量分析测定了养护后样品的组成及水泥中硅酸三钙(3CaO·SiO2,C3S)、硅酸二钙(2CaO·SiO2,C2S)的水化率;利用带固体样品测试装置的全有机碳素分析仪测定了样品所吸收的CO2量;采用水银压入法检测了样品的孔径分布.结果显示:碳化养护大大促进了低热水泥的水化,并有球霰石生成.样品中的总孔隙体积也明显减少,但有大量较大孔径的毛细孔隙存在.碳化养护前,对样品进行水中预养护可以减少这些毛细孔隙,但不利于水泥的水化并导致CO2吸收量及抗折强度显著降低.     

The Effects of Geometric Uncertainties on Micro-Channel Heat Transfer—A CFD Study on the Tilted-Cover Problem

The present paper attempts to shed light on issues that so far have been unaddressed in research on micro-channel heat transfer. The first part of the paper summarizes the uncertainty sources likely to be present in micro-channel cooling devices incorporated in the electronic package. The effects of uncertainties on the heat transfer performance of the cooling device are difficult to assess due to the coupling of diverse factors in a narrow physical space. The CFD simulation offers a means to sort out the effects from multiple factors by assuming uncertainties from one of the sources or a set of selected sources into an analytical model.

A model channel is defined to illustrate the application of the CFD-based methodology to situations involving geometric uncertainties. The model has a 20 mm × 20 mm heater plate set in a channel having an adiabatic cover and side-walls and cooled by a dielectric coolant. The tilt of the cover plate is chosen as an uncertainty factor from among all possible factors. CFD simulations were performed for the cases where the nominal channel height was changed from 1 mm to 0.1 mm with a proportionate reduction of the cover tilt from 1° to 0.1°. The results indicate a measure of required stringency in assembling the micro-channel cooling device. Also, a hypothetical experiment is considered where the performance of a channel having an optimum height is compared with that of a non-optimum channel under a given pumping power. Examination of the simulation results revealed that the cover tilts in both channels could blur or amplify the optimality of the channel height to an appreciable extent.     

Clarification of Spray-Dried Egg Yolk Suspensions and Solubilization of Proteins from Lipoproteins

The separation of proteins and lipids from spray-dried egg yolk was attempted using commerical enzymes and mold enzymes. Good solubilization of protein from a spray-dried egg yolk suspension (clarification of the suspension), could not be obtained with purified commercial enzymes (protease, lipase and phospholipase), but three crude enzymes extracted from molds and one commercial enzyme produced good results. Among them, Newlase F (crude preparation, derived from the genus Rhizopus) successfully clarified the spray-dried egg yolk suspension (pH 4.7, 40°C, 5–8 hr), thereby solubilizing about 85% of the total protein in the whole spray-dried egg yolk.     

The impact of lot sizing and sequencing on manufacturing performance in a two-stage hybrid flow shop

This paper deals with the problem of production scheduling in a two-stage hybrid flow shop, which consists of one machine in the first stage, and multiple process lines in the second stage. In the first stage, materials are batch-processed, which are then fed into one of several process lines in the second stage, depending on the final product specifications. First, we formulated the total flow time or makespan, the capacity utilization and the maximum work-in-process level as measures of manufacturing performance. We analysed, through a series of numerical experiments, how these performance measures are affected by lot sizing, sequencing rules and the scheduling scenario. The following points were clarified. (1) The ratio rule yields the best performance with regard to the makespan, but the LPT rule yields the best performance with regard to the maximum work-in-process level, (2) The optimum lot size is also affected by such operation conditions as the unit processing time, the setup time, and the ratio of unit processing times in the two stages. (3) The starting point for making a schedule should be set in the bottleneck stage with regard to the makespan.