关于沥青针入度指数

介绍了沥青针入度指数(PI)的由来和计算、使用意义、局限性和分析。     

High performance air pollution modeling for a power plant environment

The aim of this work is to provide a high performance air quality simulation using the STEM-II (Sulphur Transport Eulerian Model 2) program, a large-scale pollution modeling application. First, we optimize the sequential program with the aim of increasing data locality. Then, we parallelized the program using OpenMP directives for shared memory systems, and the MPI library for distributed memory machines. Performance results are presented for a SGI O2000 multiprocessor, a Fujitsu AP3000 multicomputer and a Cluster of PCs. Experimental results show that the parallel versions of the code achieve important reductions in the CPU time needed by each simulation. This will allow us to obtain results with adequate speed and reliability for the industrial environment where it is intended to be applied.     

用Tow-Thomas电路设计含有限非零传输零点有源滤波器的方法

Tow-Thomas电路是一种实现全极点滤波器的典型电路。本文给出了用Tow-Thoms电路设计含有限非零传输零点有源滤波器的方法，从而使Tow-Thomas电路可用于单片集成滤波器电路。而文中给出的公式可用于计算外接元件。设计实例表明了文中给出的计算公式的正确性。     

一种动态开关电容运算放大器共模负反馈电路

本文主要介绍了一种应用于Cascode结构运放中的开关电容共模负反馈电路，它具有稳定性好、对运放频率特性影响小、不消耗额外功率等优点。对电路运用Hspice进行了模拟，并给出了模拟结果。     

Two‐phase production of cyclohexene and cyclooctene oxides in water as an approach to pollution prevention

Liquid–liquid two‐phase epoxidation from cyclohexene and cyclooctene in aqueous potassium peroxymonosulfate (commercially available as Oxone^®) solution was studied as an application in pollution prevention. To avoid potential emissions of volatile organic compounds an aqueous solution was employed to replace the usual chlorinated solvents used in epoxide production. A droplet column reactor and stirred tank reactor were used to investigate two‐phase synthesis of epoxide. An aqueous Oxone^® solution was used to oxidize a dispersion of alkene droplets and form epoxide. The study of aqueous epoxidation in both reactors showed that the epoxidation of alkenes can be represented as a first order reaction with respect to alkene. The salting out effect of Oxone^® concentration was studied in both reactors and found to be very similar at optimal conditions. In comparing the two reactors, it was found that the droplet column reactor produces larger quantities of product per unit reactor volume for the same reaction time. The objective of this study is to provide an alternative reactor design and synthesis route that can meet pollution prevention goals. Copyright © 2004 Society of Chemical Industry     

美国钢铁企业的并购浪潮及特点分析

介绍了最近美国大型钢铁企业发生的主要并购活动。并对这些并购活动的特点进行了分析。     

Particle Penetration through Inclined and L-Shaped Cracks

This paper presents a particle penetration model predicting particle penetration coefficient (Pp) through a narrow crack of arbitrary incline angles (θ). The objective was to simulate Pp for outdoor-to-indoor particle penetration for residential infiltration conditions. This model assumes laminar infiltration flow and considers particle deposition from both gravitational sedimentation and Brownian diffusion. For micron-sized particles, modeling results indicate that gravitational sedimentation is the major deposition mechanism. Pp increases monotonically with ∣θ∣ because effective particle sedimentation velocity (vs?cos?θ) decreases monotonically with ∣θ∣. For submicron-sized particles (0.1?μm), Brownian diffusion is the major particle deposition mechanism. Because Brownian diffusion is a nondirectional deposition mechanism, crack inclination did not affect Pp. This study applied this model to estimate Pp for L-shaped cracks, and validated modeling results with experiments. Experimental results indicated that inertial impaction and crack entrance cutoff effects were not significant particle deposition mechanisms for the test micron-sized particles. Gravitational sedimentation was the major deposition mechanism. An L-shaped crack can be simulated as the combination of horizontal and vertical sections. This model agreed reasonably with experimental results.     

土壤中石油污染物微生物降解及其降解去向

通过多因素对比预实验，将筛选出的7个石油烃降解的主要影响因素以正交表方法组合起来，对其进行了实验研究。探讨了石油迁移转化对于各种土壤物理化学条件及其他环境因素改变的敏感程度，并找出了各主要影响因素的重要性和最佳水平；测定了土壤中所存在的石油污染物在生物降解作用下的后期产物，研究了不同条件下的样品残留污染物组分之间的差异。影响土壤中石油烃类降解的主要因素有土壤石油污染强度、营养物(NH4NO3、K2HPO4)、氧化剂(3%H2O2溶液)、表面活性剂(TW80)、温度、土壤含水率和土壤透气性；在降解的不同阶段，各个因素的重要性以及最佳水平会发生相应的变化；在生物降解后期，土壤中残留的石油污染物主要是正构和异构烷烃；正构烷烃的色谱图由原来的对称钟形变为左陡右缓的偏钟形；异构烷烃所占比重增大，正十五烷和正二十一烷之间的谱图基线被明显抬高。     

智能工程与控制技术：历史,发展与未来

本文综述了智能工程和控制技术的发展历程和基本问题。文中着重论述了人工智能在过程控制系统中的必要性及开发实时智能控制系统的步骤；对符号推理系统、耦合推理系统、人工神经网络和集成分布式智能系统的特点和局限进行了比较。最后讨论了计算机集成过程系统（ＣＩＰＳ）的基本问题、基础技术和发展前景。