Population balances for particulate processes—a volume approach

Population balance models have been used in chemical engineering since the 1960s and have evolved to become the most important tools for design and control of particulate processes. In this paper we show that the intrinsic particle parameter that determines changes in the process and should thus be included in the population balance is the particle volume. The basic population that is modeled should be the mass distribution, or the volume distribution if the density is constant. The population balance thus describes the change of the volume distribution of volume with time. Furthermore, we suggest that the “birth” and “death” terms that are often used to describe discrete events in particulate processes can almost always be replaced by a rate of change term.To design and control existing and future processes, a multi-dimensional population balance model is required. We propose a volume-based model in which the particle properties that are modeled are the volumes of solid, liquid, and air, respectively. In the most general case the model will consist of a properties vector and a distribution tensor. Depending on the complexity of the process, one or more of the properties may be omitted from the model. This is shown in three examples of increasing complexity: comminution, sintering, and granulation.     

氢化可的松母液错流萃取行为研究

将氢化可的松母液解析为氢化可的松、表氢化可的松和６α－羟基ＲＳ三种组分，模拟了母液的表观分配系数。拟合结果与实验值符合较好，平均相对误差＜５．５％。     

电动汽车机电复合制动力分配策略研究

为了实现再生制动力与机械制动力在驱动轮和从动轮之间的优化分配,在保证车辆制动安全的同时提高能量回收效率,将汽车理想制动力分配I曲线与模糊算法相结合,提出一种基于模糊控制的电动汽车机电复合制动力分配策略。设计了电动汽车再生制动力分配模糊控制器,根据车辆工况与理想制动力分配I曲线,计算前后轮上分别应加载的机电复合制动力大小。建立了电动汽车制动系统动力学仿真模型,在此基础上进行仿真分析。最后利用Advisor仿真软件对该分配策略进行回收能量效率测试。结果表明,该分配策略既能保证汽车前后轮的制动力分配按照理想制动力I曲线分布,确保汽车的制动安全;又能有效地实现再生制动能量回收,提高电动汽车的续驶里程。     

聚氨酯轮胎研发的最新进展

介绍国内外聚氨酯轮胎的研究和应用进展,对我公司聚氨酯轮胎发展历程及性能进行了详细的回顾及分析,并展望了未来聚氨酯轮胎的发展趋势以及应用前景。     

热处理对照相明胶溶液粘度和分子量分布的影响

本文以四种照相明胶为研究对象，探讨热处理对照相胶胶溶液粘度和分子量分布的影响，实验结果表明，随着加热温度上升，照相明胶溶液粘度下降，数均分子量下降，照相明胶溶液粘度和数均分子量密切相关，照相明胶溶液粘度下降发生的内在原因是数均分子量下降，在本实验条件下，惰胶、活性胶的加热温度不超过７５℃，ＰＡ胶的加热温度不超过６０℃。     

Improved methods for evaluating the molar mass distributions of cellulose in kraft pulp

Multi‐angle laser light scattering (MALLS) was used to characterize birch kraft pulps with respect to their absolute molecular mass distributions (MMDs). The pulps were dissolved in lithium chloride/N,N‐dimethylacetamide and separated by size exclusion chromatography (SEC). The weight‐average and number‐average molecular masses of the cellulose fractions of the pulps obtained from the absolute MALLS measurements were compared with the molar masses obtained by direct‐standard‐calibration relative pullulan standards. Discrepancies between the two detection methods were found, and two ways of correlating the relative pullulan molar masses to the absolute molar masses were examined. In the first method, the correlation was made over a large range of molecular masses. The second method correlated the molecular masses of the standards to the molecular masses of samples by the calculation of fictitious, cellulose‐equivalent molar masses of the standards. With the preferred second method, a more correct MMD of kraft pulp samples could, therefore, be obtained from an SEC system calibrated with narrow standards. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1170–1179, 2003     

双峰PE80级管材专用树脂的开发

介绍了高密度聚乙烯管材专用树脂6366M的结构特性、物理性能及其加工应用试验的情况。结果表明，6366M具有相对高的相对分子质量，其相对分子质量分布结构特性呈双峰分布。该材料具有优异的力学性能和耐环境应力开裂性能，而且加工性能较好，实现了刚性和韧性的平衡。成品管材的性能指标可以满足用户的需求。     

Modelling of membrane nanofiltration—pore size distribution effects

The effects of log-normal pore size distributions on the rejection of uncharged solutes and NaCl at hypothetical nanofiltration membranes have been assessed theoretically. The importance of pore radius-dependent properties such as solvent viscosity and dielectric constant is increased by the introduction of a pore size distribution in calculations. However, the effect of porewise variation in viscosity is less apparent when considered at a defined applied pressure rather than at a defined flux, showing a further advantage of basing theoretical analysis of nanofiltration in terms of applied pressure.Truncated pore size distributions gave better agreement than full distributions with experimental rejection data for a Desal-DK nanofiltration membrane. Such truncation is in agreement with the findings of atomic force microscopy (AFM). Analysis of uncharged solute rejection data alone could not give useful information about membrane pore size distribution. Neither could such a distribution be obtained quantitatively directly from AFM images. However, use of the shape of the distribution obtained by AFM in conjunction with experimental rejection data for an uncharged solute allows calculation of corrected distributions. Importantly, incorporation of such a corrected pore size distribution in calculations of NaCl rejection gave better agreement with experimental data, compared to calculations assuming uniform pores, at high pressure, the region of industrial interest.     

基于非线性关联维特征提取的机械自动化监测系统

提取天然气压缩机故障状态下振动信号的故障特征是设计机械自动化检测系统的核心技术。提出一种基于非线性关联维特征提取的机械自动化监测系统设计方法,在故障诊断原理基础上,进行故障振动信号时间序列分析,设计故障振动信号相空间重构方法,改进了相空间重构最佳时延和嵌入维数参数计算的关键技术,通过提取关联维故障特征,在Simulink平台上设计了自动化监测系统。系统实验结果表明,该算法和系统能使各类故障状态下提取的关联维特征的标准差显著性降低,特征分布聚类能力明显提高,系统能有效检测各类故障,实现了机械设备的自动化监测,在自动化故障诊断仪表设计等领域具有较好的工程实践价值。     

重金属在宽叶香蒲人工湿地系统中的分布与积累

本文通过对广东韶关凡口宽叶香蒲（Typha latifolia)人工湿地系统的进出水口，土壤剖面及四种优势植物体各部分器官中Pb,Zn,Cu和Cd含量进行分析。结果表明；重金属主要库存于土壤中。从水平上看，全量的重金属含量从进水口到出水口呈上升趋势，而有效态则相反；从土壤剖面的垂直分布上看，全量和有效态重金属含量都随土壤深度的增加而递减，四种植物都具有较强的吸收和富集重金属的能力，且主要富集在植物的地下部分。