ON THE COMPOSITION-DEPENDENT INTERACTION PARAMETERS IN EQUATIONS OF STATE

Composition-dependent interaction parameters have been applied to the calculation of vapor-liquid equilibria (VLE) in mixtures containing components of different chemical nature. Binary VLE have been correlated and ternary VLE have been predicted from binary data using five different mixing rules. Binary data can be accurately correlated for systems with moderate deviations from ideality using mixing rules with two binary parameters. For very strongly nonideal mixtures three binary parameters are needed. For the prediction of ternary VLE from binary information only the mixing rules of Panagiotopoulos and Reid (1986) and Schwartzentruber et al. (1987) are reliable. For most systems the quality of predicting ternary data is comparable to the quality of correlating binary data. Significant deviations are noted only for strongly nonideal systems close to phase separation. In these cases it is recommended to use models incorporating association in an explicit form. KEYWORDS Equations of state Mixing rules Multicomponent Vapor-liquid equilibria.     

Coagulation of Particles Through Rapid Mixing

As is often assumed, rapid mix effectively distributes the dosed coagulant in suspension to promote subsequent flocculation of suspended particles and coagulant molecules. This study determined that the role of rapid mix is considerably more complex than conventionally assumed. Particles in the raw water samples from the Banxing Water Works of Taipei City were coagulated at high shear environment, during which flocs of size 40-70 μm were produced. The produced floc interior was compacted, and residual turbidity and the amount of dissolved natural organic matter (NOM) in suspension were substantially reduced. The subsequent stage of rapid mix slightly reduces floc size, further compacts the floc interior, and expels fine particles and some adsorbed NOM from the flocs. A sudden reduction in shearing rate produced large sized flocs with not so compact structures. Moreover, this action released fine particles from flocs into the suspension and enhanced adsorption of NOM onto solid surfaces.     

Temperature Dependence of Thermal Emission Rate in Cr:GaAs

The new method of measuring the ratio of thermal emission rate to the photoexcitation constant os presented.The temperature dependence of the ratio for Cr:GaAs is calculated by using the previously published data of two- wave mixing,Results show that the calculating data and previous phenmenological theoretic ones coincide with each other very well.     

Motility,mixing, and multicellularity

A fundamental issue in evolutionary biology is the transition from unicellular to multicellular organisms, and the cellular differentiation that accompanies the increase in group size. Here we consider recent results on two types of “multicellular” systems, one produced by many unicellular organisms acting collectively, and another that is permanently multicellular. The former system is represented by groups of the bacterium Bacillus subtilis and the latter is represented by members of the colonial volvocalean green algae. In these flagellated organisms, the biology of chemotaxis, metabolism and cell–cell signaling is intimately connected to the physics of buoyancy, motility, diffusion, and mixing. Our results include the discovery in bacterial suspensions of intermittent episodes of disorder and collective coherence characterized by transient, recurring vortex streets and high-speed jets of cooperative swimming. These flow structures markedly enhance transport of passive tracers, and therefore likely have significant implications for intercellular communication. Experiments on the Volvocales reveal that the sterile flagellated somatic cells arrayed on the surface of Volvox colonies are not only important for allowing motion toward light (phototaxis), but also play a crucial role in driving fluid flows that transport dissolved molecular species. These flows, generated by the collective beating of flagella, confer a synergistic advantage with regard to transport of nutrients and chemical messengers. They allow these species to circumvent a nutrient acquisition bottleneck which would exist if transport were purely diffusive, and thereby evolve to larger multicellular individuals. In both cases, a higher level of organization, specialization and complexity counteract the higher costs inherent to larger groups.     

神湾盛世游艇制造基地水利工程水泥搅拌桩施工及质量控制

结合广东省中山市神湾盛世游艇制造基地水利工程工程地质条件,阐述了水泥搅拌桩干法施工技术在软土地基基础处理中的应用及质量控制要点。该工程搅拌桩施工了约93万m,成桩后经检验各项指标均满足设计要求,工程质量稳定。     

粉喷搅拌桩机的计算机控制系统研制

介绍了粉喷搅拌桩机的机理和工艺过程。简述粉喷搅拌桩机的计算机控制结构。     

离子束混合诱导稀土金属Ce与Si的界面反应及硅化物的形成

本文详细讨论了离子束混合下,Ce/Si〈100〉双层膜体系界面反应的动力学过程以及硅化物的形成规律.样品经150KeV Ar离子注入,辐照温度从LNT到300℃,剂量从5×X10~(14)到8.1×10~(16)Ar/cm~2.界面反应形成的硅化物为CeSi_2,其结构为体心正交结构.硅化物是分层生长的,厚度与注入剂量的平方根成线性关系,这说明界面反应是扩散控制的.与近贵金属/硅体系和难熔金属/硅体系相比较可以看出,稀土金属Ce/Si体系的相变过程与难熔金属/硅体系的相似;而混合的动力学行为与近贵金属/硅体系的相似.本文还讨论了化学驱动力和辐射增强扩散对混合的贡献.     

SORPTION DRYING OF SOYBEAN SEEDS WITH SILICA GEL. I. HYDRODYNAMICS OF A FLUIDIZED BED DRYER

ABSTRACT

Fluidization technology has been employed to mix soybean seeds and silica gel particles in aim of sorption drying of particulate agricultural products. The characteristic fluidization velocities, mixing mechanisms and fluidization quality have been studied in a 180 mm I.D. fluidized bed. Two sizes of silica gel particles (SG2 and SG3) were selected, with the mass fractions in the range of 0.33–0.75 to form a static bed with height from 100 to 280 mm (H/D = 0.56–1.56). The results show that the dispersion rate of soybean seeds is increased with addition of either SG2 or SG3, and that the frequency and the span of pressure fluctuations within the bed are increased. It is inferred that the gas–solids contacting is improved with addition of small particles in the bed of large particles. In addition, for practical design and operation of such a fluidized bed of binary mixtures, empirical correlations for characteristic fluidization velocities were developed with a wide application.     

A method for computing the degree of mixing in steady continuous flow systems

The degree of mixing was first proposed by Danckwerts and further discussed by Zwietering more than 50 years ago to measure mixing performance of a continuous flow system. Although the measure has been widely discussed in mixing literature, there has never been a method to compute its value for a general continuous flow. In this paper, a method is developed to compute this measure for a general steady continuous flow system for the first time. The method is based on the recently developed mean age theory. The governing equations for the mean age and higher moments of age are also derived for different types of tracer introduction other than pulse input in the current mean age theory.