掺气减蚀保护作用的新概念

利用针式掺气流速仪测量原型和模型掺气浓度场、流速场，气泡尺寸及其概率分布的研究成果表明，原型水流韦伯数高，形成微小气泡的能力比模型强，气泡上浮慢，接近底部的小尺寸气泡概率及掺气浓度比模型大。初步研究认为：0.2mm或0.5mm以下的微小气泡在掺气减蚀中起着主要作用，可能只要很小掺气浓度即可达到掺气减蚀的效果。因此以小尺寸气泡的掺气浓度，作为判断掺气减蚀保护作用的指标将更为准确。     

矩形垂直筛板的流体力学性能研究

在600mm的有机玻璃冷模塔中,用水-空气体系测定矩形垂直筛板的塔板压降、漏液和雾沫夹带等流体力学性能,确定了合理的塔板结构,使其具有较高的气液通量和较宽的操作范围,空塔动能因子最大可达3.0kg1/2(m1/2.s)-1,液流强度可达21.6m3/(m.h)。并对不同气液流量下塔板的流体力学实验数据进行关联和分析,得出了矩形垂直筛板的干板压降计算关联式以及漏液率随液流强度和空塔动能因子的变化关系,为矩形垂直筛板的设计提供了依据。与新垂直筛板相比,矩形垂直筛板具有更低的塔板压降。     

The effect of pre-wetting on dynamic contact angles

A roll-coating experimental system is used to study the effect of pre-wetting on dynamic contact angles, the interfacial displacement depth, and the associated phenomenon of air entrainment. The system consists of a roll, which is horizontally rotating in a liquid pool. The dynamic contact angle is recorded by a macrophotography system. The test liquids are glycerol solutions with viscosities in the range 104 < μ < 748 mPa · s. The value of (μV/ρg)^0.5 is taken as the characteristic length to be used in the dimensionless relationships which correlate experimental measurements. The effect of base layer entry angle into the liquid pool on the dynamic contact angles and other flow parameters is studied. Comparison is made with measurements in dry tape-coating and other pre-wet roll–coating systems.     

You said it before and you'll say it again: Expectations of consistency in communication.

Repeated reference creates strong expectations in addressees that a speaker will continue to use the same expression for the same object. The authors investigate the root reason for these expectations by comparing a cooperativeness-based account (Grice, 1975) with a simpler consistency-based account. In two eye-tracking experiments, the authors investigated the expectations underlying the effect of precedents on comprehension. The authors show that listeners expect speakers to be consistent in their use of expressions even when these expectations cannot be motivated by the assumption of cooperativeness. The authors conclude that though this phenomenon seems to be motivated by cooperativeness, listeners' expectation that speakers be consistent in their use of expressions is governed by a general expectation of consistency. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Modeling Effects of Rhythmic Context on Perceived Duration: A Comparison of Interval and Entrainment Approaches to Short-Interval Timing.

Relative merits of interval and entrainment conceptions of the internal clock were assessed within a common theoretical framework by 4 time-judgment experiments. The timing of tone onsets marking the beginning and ending of standard and comparison time intervals relative to a context rhythm were manipulated: onsets were on time, early, or late relative to the implied rhythm, and 2 distinct accuracy patterns emerged. A quadratic ending profile indicated best performance when the standard ended on time and worst performance when it was early or late, whereas a flat beginning profile (Experiments 1-3) indicated uniform performance for the 3 expectancy conditions. Only in Experiment 4, in which deviations from expected onset times were large, did significant effects of beginning times appear in time-discrimination thresholds and points of subjective equality. Findings are discussed in the context of theoretical assumptions about clock resetting, the representation of time, and independence of successive time intervals. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

挑坎型掺气减蚀设施过流掺气特性研究

采用一维激光测速系统，对掺气减蚀工程中常用的直线型挑坎的流场特性进行试验研究．通过测量挑坎上及空腔区水流的流速分布及紊动特性，探讨通气量与紊动强度的关系．同时在深入研究流场特性和掺气机理的基础上，通过分析影响掺气的因素，从理论上探求临界掺气流速的计算，重点分析挑坎型掺气过流在空腔负压较大的情况下，临界掺气条件的理论预测，并通过试验资料验证了该计算方法．在此基础上，还进一步研究了掺气量的计算公式及其变化规律．     

Air entrainment in fresh concrete with PFA

The results of a study into the influence of PFA on air entrainment in fresh concrete are discussed It is shown that the required dosage of AEA to produce an air content of 5.5 ± 0.5% in a PFA modified concrete mix is two-six times that required in the corresponding neat OPC concrete mix. The dosage of a vinsol based air entraining agent (AEA) required appears to be directly related to the PFA content of the mix. Similar direct relationships were obtained with a range of different PFAs. The dosage of an AEA based on the salt of a fatty acid appears to be sensitive to both PFA and OPC contents. For the type of PFA used, the variability of measured air content or the amount of air retained after continued agitation both indicated that vinsol based AEAs show the highest variability whilst fatty acid based AEAs show low variability. The between batch variability of air content was significantly improved by the addition of PFA regardless of the AEA used.     

Assessment of Bitumen Re c overy from the Athabasca Oil Sands Using a Laboratory Denver Flotation Cell

A methodology was developed in this study to evaluate the effect of operating parameters on the processability of oil sands using small‐scale laboratory experimental devices. By subtracting bitumen recovered to the froth by entrainment with water, the concept of “true flotation recovery” is proposed to describe bitumen recovery resulting from bitumenbubble attachment. The experimental results indicated that “true flotation recovery” is a more sensitive and meaningful marker than overall bitumen recovery to evaluate the processability of oil sands using small‐scale laboratory test units.     

前置掺气坎式阶梯溢洪道体型特点及工程应用试验研究

为了避免阶梯溢洪道中前几级阶梯表面发生空蚀破坏,将掺气坎应用到阶梯溢洪道体型设计中,形成前置掺气坎式阶梯溢洪道。这既能充分利用阶梯增加沿程消能的优点,又能扩宽阶梯溢洪道的应用范围。工程模型试验成果表明,通过掺气坎和阶梯的体型优化,各级流量的消能率均达到70%左右。1:40物理模型试验上实测溢洪道阶梯竖直面后的掺气浓度沿程分布均大于5%。研究表明这种新型阶梯溢洪道掺气量与掺气浓度易于控制,底部掺气充分,抗空蚀性能优越,消能率高,可以在高水头、大单宽流量溢洪道中推广应用。