生物洁净室的污染控制

生物洁净室的目的是控制细菌污染。通过对细菌特性、来源及污染途径的分析,确定了全方位、全过程控制的基本思想,即污染源控制,污染传播过程控制和交叉污染控制,通过分析微粒的运动特性,提出了空气途径污染的主要手段是气流流动控制和表面污染控制,最后分析了交叉污染的形成原因及其防治措施。     

物质波理论与经典力学

讨论了微观粒子波粒二象性概念的形成及其影响。证明了经典力学中，力的概念的局限性及其在量子力学和相对论中都没有存在价值。     

Sampling frequency and accuracy of SPM flux estimates in two contrasted drainage basins

The present paper is based on discharges and suspended particulate matter concentrations from a 9-years high-resolution database for the Garonne River (large plain river) covering contrasted hydrologic years, and a 12-months high frequency sampling for the Nivelle River (small mountainous river). Annual SPM fluxes in the Garonne River range from 0.6 x 10(6) t year(-1) (1997) to 3.9 x 10(6) t year(-1) (1996). In contrast, the Nivelle River transported 11 x 10(3) t year(-1) from December 1995 to December 1996. From the long-term observation of the Garonne River an empirical relation between SPM* (discharge-weighted mean annual SPM concentrations) and annual discharge was established. This relation allows estimating annual SPM fluxes for the Garonne River with less than 30% deviation from reference values for the whole range of mean annual discharge observed during the past decade. Specific (=area-normalized) annual SPM fluxes (YSPM) range from 11 to 74 t km(-2) year(-1) for the Garonne River. Comparison of these results with YSPM of the Nivelle River (69 t km(-2) year(-1) in 1996) suggests that interannual hydrological variations may have a greater impact on fluvial SPM transport than basin-specific parameters. By extracting individual SPM concentrations and corresponding discharge values from the database, different sampling frequencies were simulated and resulting SPM fluxes were then compared to reference fluxes derived from the complete database. If a deviation of simulated flux estimates from reference fluxes lower than +/-20% is accepted, the Garonne River (large plain river) must be sampled at least every 3 days (10 samples per month) and the Nivelle River every 7 h (approx. 100 samples per month). For the Garonne River this minimum sampling frequency is valid for all contrasted hydrologic years of the observation period. Below these minimum sampling frequencies, annual SPM flux estimates may greatly differ from reference fluxes (up to 200%) and there is high probability of systematic underestimation. Consequently, annual SPM flux estimates for the Garonne River derived from the empirical relation (SPM*-annual discharge) are likely to be more satisfactory (errors <30%) than estimates based on sampling frequencies lower than the minimum frequency. These findings underline the need of adapted sampling strategies for erosion assessment, reliable chemical (e.g. nutrients and pollutants) mass balances and characterisation of fluvial transport mechanisms in the world's contrasted watersheds.     

核分析相关技术用于上海市大气污染特征研究

本文研究了近年来上海市区和郊区大气气溶胶颗粒物的污染状况,采用的多种核分析方法及相关技术有质子激发X荧光分析(PIXE)、激光粒径谱仪(LPS)、同步辐射X射线吸收精细结构(XAFS)和扩展X射线吸收谱精细结构(EXAFS)分析等先进技术.充分发挥核分析技术高灵敏度、快速无损、多元素微量微区同时分析的优势,从大气颗粒物的形貌特征、粒径分布、质量浓度、元素浓度、化学价态等入手,对上海大气可吸入颗粒物PM23和PM1o展开多方位的综合研究.     

直流氩等离子体硅粉纯化工艺的研究

针对立式反应室、直流氩等离子体情况,建立硅粉的运动学模型,绘出粉粒沉降时间与粉粒粒度和进气速率的关系曲线,并通过该模型选择进气速率为4～10L/s,粉粒的粒度范围为70～100μm.为了提高粉粒沉降过程中纯化效果,建立并分析鞘层模型中与鞘层厚度、鞘层区离子浓度以及鞘层离子平均动能有关的工艺参数的变化关系并提出一套优化选择放电参数的方法.通过该方法优化工艺参数为反应室总压力为4～6Pa,阴极电压为2000V或是更高,鞘层厚度为1.2～2cm.提纯实验结果表明,硅粉的纯度可由99.6%提高到99.95%.     

气固搅拌流化床内的压力脉动特性

为考察搅拌桨的转动作用对流化特性的影响，研究了不同转速和气速下搅拌流化床的压力脉动行为.采用188 mm的内径和400 mm的静床高，以Geldart B类和D类颗粒为实验物料，进行了压力脉动信号的统计分析和功率谱分析.实验结果表明，搅拌桨的转动对最小流化速度没有影响，但使B类和D类颗粒呈现了A类颗粒特有的散式流态化现象.随搅拌转速的增大，压力脉动的标准偏差减小，最小鼓泡速度增加. 最小鼓泡速度与最小流化速度之比与搅拌转速成正比.当搅拌转速增加到一定程度后，压力脉动的功率谱主频等于搅拌桨转动频率，流化床从鼓泡流态化状态转化为散式流态化状态.     

柴油机NOX和PM排放控制技术的发展

NOX和PM是柴油机排放的主要污染物,文章分别介绍了目前国内外应用的减少柴油机NOX和PM排放的方法,并分析了其各自的优缺点.     

重庆三峡库区非点源污染来源分析及负荷计算

通过2000年统计资料,分析了重庆三峡库区农村生活污水、固体废弃物、化肥流失、农药流失、畜禽养殖、水土流失、城市径流等污染源对非点源污染物COD、NH3-N、TN、TP的贡献。运用RUSLE模拟计算颗粒态污染负荷并结合溶解态污染负荷,估算入库非点源污染总负荷。得出库区颗粒态N负荷(占TN的50.1%)与溶解态N负荷(占TN的49.9%)相当;颗粒态P负荷(占TP的58.0%)略大于溶解态P负荷(占TP的42.0%)。该方法给湖泊、水库等水体底质再悬浮与释放溶解态N、P的迁移研究提供了计算颗粒态污染负荷和溶解态污染负荷的简洁方法。     

基于电除尘器与煤质数据库的电厂煤质分析与除尘技术路线选择

随着环保要求和排放标准的日益严苛，对燃煤电厂超低排放的研究受到更多关注。建立了电除尘器与煤质数据库，包含了数百家燃煤电厂的煤质参数、电除尘器设计及运行参数。基于该数据库，对燃煤电厂动力煤的灰含量、硫含量分布情况进行分析。研究发现，从灰含量看，西南地区多燃用高灰煤，东北、华中、华北地区多燃用中灰、中高灰煤，沿海地区燃煤电厂多燃用特低灰、低灰煤；从硫含量看，西南地区燃煤电厂多燃用高硫煤，山东、山西、河南、河北等地区的燃煤电厂多燃用中硫煤，其他大部分地区多燃用特低硫、低硫煤。通过分析3座分别燃用低灰低硫、中灰中硫和高灰高硫煤电厂的颗粒物超低排放技术案例，针对不同煤质提出了颗粒物超低排放技术路线建议。     

Heating/Drying Using Particulate Medium : A Review Part I. General and Heat transfer parameters

ABSTRACT

This paper presents an Overview of particulate medium drying and heat treating of cereal grains. While the conventional air drying of grains is well documented, studies on the drying of grains using heated granular medium do not appear to exist. The scientific study of the different aspects of drying with a heated granular medium began in the early 1970's. Progress on the utilization of particle-to-particle heat transfer was slow as evidenced by the fact that there is no commercial dryer using the method as of today.

The first section of this paper deals with conduction heating and how it led to the use of granular medium in heating the grain. Starting with the earliest work on conduction heating reported by Kelly ( 1939), the developments in the heating of grain using granular media is discussed. For decades since Kelly's report, work in the subject area dealt mostly with the theoretical aspects of solid-to-solid heat transfer. Thus, in the succeeding section of the paper, heat transfer parameters and mechanisms involved in the process are thoroughly investigated.