Assessment of Capillary Rise from Shallow Groundwater by the Simulation Model SIMWASER Using Either Estimated Pedotransfer Functions or Measured Hydraulic Parameters

The performance of the water balance and crop growth model SIMWASER to estimate the water supply of a lawn by capillary rise from shallow ground water was investigated by using lysimeter measurements with a sandy and a clayey soil. Moreover the robustness of the model was evaluated by running it either with measured hydraulic soil parameters or with estimated pedotransfer functions (PTFs) derived from texture and bulk density. Simulations were performed for the years 1996–1998 with input data from the lysimeter station Berlin-Dahlem (Germany) for lysimeters containing undisturbed sandy or clayey soil monoliths, with groundwater at 135 cm depth. Simulated evapotranspiration and percolation/capillary rise were in good agreement with the measured data for all variants, while simulated soil water storage was acceptable only for the variants using hydraulic soil data based on laboratory measurements or using PTFs derived from known soil class and bulk density. PTFs based on mean total pore volume of the respective soil classes yielded soil water storages which were evidently too high; therefore they should be used with care and must be avoided at all in simulating the soil water balance of arid sites with shallow groundwater.     

毛细管微反应器中乙烯环氧化反应

在石英毛细管中涂覆α-Al2O3并负载银,制成微反应器,利用毛细管微反应器进行了乙烯环氧化反应的实验。考察了反应温度、乙烯含量、气态空速等因素对乙烯环氧化反应的影响。实验结果表明,在毛细管微反应器中可进行乙烯环氧化反应,在常压、不添加任何助催化剂和抑制剂的条件下,反应温度为230℃时,乙烯的转化率为69.54%,环氧乙烷的选择性和收率分别为82.00%和57.02%;毛细管微反应器的气态空速可达到5600h-1,超过工业装置的水平,缩短了反应时间,减小了深度氧化的几率。     

制冷剂充灌量和毛细管长度对空调系统性能的影响

在空调器的匹配中，制冷剂充灌量和毛细管长度是两个非常关键的因素。本文采用理论与数值计算的方法，对制冷剂充灌量和毛细管长度对空调系统性能的影响进行了分析，为空调器的优化设计匹配、提高空调器的性能奠定了基础。     

台式毛细管放电X光激光装置调试实验

对自行研制的台式毛细管放电X光激光装置进行了系统调试,在充氩气毛细管负载下,输出电流38kA,电流脉冲前沿40ns,并对有关问题进行了讨论.并在这个装置上开展充氩气毛细管放电荧光光谱实验研究.     

Mathematical analysis of viscometric (polymer) flow fields in capillaries: Taylor dispersion revisited

A general formulation for capillary flow of two miscible fluids – one a dilute plug of polymer fluid inserted into a fully developed Poiseuille flow of the other, a Newtonian stream – is examined for its long time behavior. Phenomenologically, the system evolves from an initial state, that of a plug within the boundaries of sharp, well defined fronts inside a Newtonian stream, to a more homogenized state in the very long time scale. This problem was addressed by G.I. Taylor but with regard to a system of two Newtonian fluids, leading to the well-known results commonly described as `Taylor axial dispersion'. In this paper, a general and systematic perturbation analysis is presented from which Taylor's result is recovered as a special case of a more general solution which applies to fluids incorporating elastic properties. In particular, the influence of viscoelasticity and (polymer) diffusivity on the observed pressure profile in the capillary conduit is examined. This effect is clearly separated out for small Peclet number flows using asymptotic and numerical analysis. The results identify the influence of fluid viscosity, elasticity, and diffusivity on the observed pressure profile and form the basis for the improved characterization of polymeric elasticity using capillaries – a finding that is of significant scientific and commercial interest. These results were obtained by the authors as a class of observations resulting from the perturbation analysis of forced-flow capillary devices in viscoelastic fluid property investigation.     

灭蚊窗涂剂的毛细管柱气相色谱分析

介绍了用AT-101毛细管柱，以邻苯二甲酸二正戊酯为内标，对灭蚊窗涂剂中3种有效成分残杀威、氯菊酯、氯氰菊酯同柱同条件下定量分析的方法。该方法的分析时间短，准确度、精密度高，重现性好。     

土体中毛细水压力的研究

该文从毛细水产生负孔隙水压力概念入手 ,对较难确定的孔隙水压力系数以及较抽象的地下连续墙时效稳定分析等问题进行了定量计算 ,以期对工程实践有一定的指导作用     

一个低电阻率油气藏的测井评价

根据J油田大量岩芯分析资料,应用油藏流体分布理论和毛管压力计算方法,研究该油田低电阻率油气层的形成原因认为:地层水矿化度高(多数>20万ppm);微细孔隙发育,束缚水含量高;粘土矿物含量高且分布在碎屑颗粒表面等是形成低电阻率油气层的主要原因.一般常规测井评价时,对这种低电阻率油气层容易误释而丢弃.依据油气藏流体分布原理,应用毛管压力方法计算原始含油饱和度,可准确地识别出这种低电阻油气层,并可预测其产能.     

Finite-size effects in surface tension: Thermodynamics and the Gaussian interface model

It has been suggested by Kayser that finite-size effects associated with capillary waves might play a significant role in some surface tension measurements; for capillary rise between plates a distance D apart, an effect varying as 1/D and apparently observable in measurements, was proposed. In reconsidering this problem, one must analyze the thermodynamics of finite-size corrections to surface tension. In particular, one sees that capillary rise between plates does not measure the interfacial free energy density but, rather, a derivative of the interfacial free energy with respect to a system dimension. The quantity needed to draw definite conclusions, the finite-size residual free energy, can be calculated within the harmonic or Gaussian capillary wave model in d spatial dimensions with the aid of Poisson summation techniques and should yield the correct leading asymptotic behavior. For d=3 and experimentally relevant parameter values, the results are independent of the short-wavelength cutoff needed in the model and can be checked against the theory of conformai covariance at two-dimensional critical points. It is found that the finite-size effects in capillary-rise measurements of surface tension vary as 1/D ² (with a universal coefficient) but are too small to be seen in current experiments.Invited paper presented at the Tenth Symposium on Thermophysical Properties, June 20–23, 1988, Gaithersburg, Maryland, U.S.A.     

Coalescence dynamics of two droplets of different viscosities in T-junction microchannel with a funnel-typed expansion chamber

The coalescence behavior of two droplets with different viscosities in the funnel-typed expansion cham-ber in T-junction microchannel was investigated experimentally and compared with droplet coalescence of the same viscosity.Four types of coalescence regimes were observed:contact non-coalescence,squeeze non-coalescence,two-droplet coalescence and pinch-off coalescence.For droplet coalescence of different viscosities,the operating range of non-coalescence becomes narrowed compared to the droplet coalescence of same viscosity,and it shrinks with increasing viscosity ratio η of two droplets,indicating that the difference in the viscosity of two droplets is conducive to coalescence,especially when 1 ＜ η＜ 6.Furthermore,the influences of viscosity ratio and droplet size on the film drainage time (Tdr) and critical capillary number (Cac) were studied systematically.It was found that the film drainage time declined with the increase of average droplet size,which abided by power-law relation with the size dif-ference and viscosity ratio of the two droplets:Tdr ～ (ld)0.25±0.04 and Tdr ～ (η)-0.1±002.For droplet coales-cence of same viscosity,the relation of critical capillary number with two-phase viscosity ratio and dimensionless droplet size is Cac =0.48λ0.26l-2.64,while for droplet coalescence of different viscosities,the scaling of critical capillary number with dimensionless average droplet size,dimensionless droplet size difference and viscosity ratio of two droplets is Cac =0.11 η-0.07ls-2.23ld0.16.