室内颗粒物分布运动的研究进展

室内颗粒物是影响室内空气品质的主要因素之一,长期暴露于颗粒物质中,对人们的呼吸健康将产生不利影响,因而对室内颗粒物的分布和穿透、沉降及二次悬浮等动力学行为进行研究非常必要。本文阐述了近几年室内颗粒物分布运动的理论分析和实验研究进展,分析了目前研究中存在的问题,并提出今后研究工作的方向。     

水中悬浮隧道研究进展浅析

随着海上交通运输的发展,海峡隧道的研究引起了越来越多专家学者的关注。国外早在1880年便提出了SFT(水中悬浮隧道)的概念,国内对SFT的研究起步较晚。文中通过查阅国内外的相关文献,旨在对SFT工法及受力特点的研究进行介绍,特别是水中悬浮隧道的锚固类型、与水中悬浮隧道相关的荷载及相关计算方法和影响水中悬浮隧道动力特性的相关因素做出讨论,最后对SFT现存问题做出总结并对未来发展做出展望。     

聚丙烯纤维对高温作用下C60HPC板热应变的影响

为了改善混凝土板在高温作用下热应变的变化程度,本文将聚丙烯纤维(简称PP)掺入到C60HPC小板中,研究其对混凝土热应变及温度传递的影响,试验设计了素混凝土、PP体积掺量分别为0.1%、0.2%、0.3%的4块C60HPC小板,模拟高温试验,测试混凝土小板不同深度处(距离小板受火底部25、50、75 mm)的温度及对应的热应变值,分析热应变值随时间和受火温度的变化规律,研究PP纤维对C60HPC小板热应变的影响。结果表明:不同PP纤维掺量的C60HPC小板在不同深度处的热应变值随着时间的变化基本呈直线上升的变化规律;掺PP纤维对高温作用下C60HPC小板的热应变有一定的抑制作用,最优PP纤维掺量为0.2%;在一定温度范围内,PP纤维掺量为0.2%的C60HPC小板热应变和温度基本呈二次函数关系,相关性较好。     

颗粒物尺度对滤料过滤性能的影响

介绍了不同学者对滤料过滤机理的研究结果,实验研究了颗粒物尺度对粗、中、高效滤料过滤效率和过滤阻力的影响,对合理选择空调系统过滤材料提出了建议。     

政府投资项目HPC模式的探讨

目前大多数政府投资项目已经不再拘泥于传统的管理组织模式,而是逐渐融合多种项目管理经验,发展适应于具体项目的组合模式。现实中组合模式的开发存在多重困难,而正确地运用组合模式也是项目管理面临的一大难题。为此探讨了政府投资项目HPC模式,并进行了治理分析。     

基于模糊综合评价的水中悬浮隧道风险分析

水中悬浮隧道的研究历史虽然很短,但得到了很多人的关注.究其原因在于这种结构形式的新颖性和潜在的应用前景.因此,目前在悬浮隧道研究的起步阶段,通过风险分析研究悬浮隧道结构的可行性就显得尤为必要,论文通过模糊综合评价方法对悬浮隧道的整体风险进行了分析,把悬浮隧道结构整体风险因素可分为八类,得到了其安全风险的量化数值,认为该结构的风险等级为中度风险,其风险应在人们可接受的范围内.悬浮隧道的可行性研究方面做了初步探索.     

复合超塑化剂（CSP）对FLC和HPC坍落度损失的控制

1　前　言现代混凝土工艺要求流态混凝土 (ＦＬＣ)和高性能混凝土 (ＨＰＣ)具有好的工作性 ,以满足集中搅拌、远距离运输、泵送、不振捣、自流平、自密实等过程的要求。新拌混凝土的工作性 ,包括大流动性、坍落度损失小、抗离析性和可泵性。其中最重要的是坍落度损失问题。研究表明 ,水泥的矿物组成 (主要是Ｃ3Ａ、Ｃ3Ｓ)和含碱量、混合材种类和掺量、水泥细度和颗粒组成、混凝土配合比和强度等级、掺合料品种和掺量以及复合超塑化剂 (ＣＳＰ)的组成和掺量等因素都影响坍落度损失速度。传统观点认为掺高效减水剂的同时 ,掺缓凝剂能减小坍落…     

单颗粒物料在水平管中被悬浮输送时所受升力的探讨

在气力输送设计中,使物料悬浮输送时的最佳气流速度的估计,是众多理设工作者和工程技术人员关心的课题。依据流体力学理论,本文获得了球形物料在水平管道中被悬浮输送时的马格努斯效应,并在理论分析与实验观察的基础上,用拟合的方法获得了单颗粒物料在水平管道中被悬浮输送时的气流速度,在工程设计中有一定的参考价值。     

交通源颗粒物对小区内环境的影响

利用湍流k-ε模型及离散相模型(DPM)研究了小区外交通源(线源)排放颗粒物对小区内环境的影响。对比分析了有、无围墙情况下,小区内环境受交通源污染物的影响状况。结果表明:围墙对颗粒物有很好的阻挡作用。因围墙的存在,颗粒物大部分积聚在小区外、围墙附近。虽然部分颗粒物能够进入小区,由于其浓度很低,小区环境基本不受影响。但是,无围墙存在时,颗粒物无阻挡地进入小区,小区受交通源颗粒物的影响很大,特别是前排建筑物的迎风面和绕流区域。     

Adsorption of lead on the suspended particles of river water

The effects of the chemical composition and particle size, of suspended particles in river water, on the adsorption of lead onto these particles have been studied. Lead has been determined using the conventional method of anodic stripping voltammetry. Particle sizes have been determined using the Coulter Counter. The organic matter content of the suspended particles has been found responsible for most of the lead adsorbed onto these particles. An attempt has been made to quantify the relationship between the particle size of suspended particles and the amount of lead adsorbed onto these particles. The shape of the calibration graphs of lead from solutions in river water has been explained with reference to the adsorption of lead on suspended particles.     

Impact of particles on sediment accumulation in a drinking water distribution system

Discolouration of drinking water is one of the main reasons customers complain to their water company. Though corrosion of cast iron is often seen as the main source for this problem, the particles originating from the treatment plant play an important and potentially dominant role in the generation of a discolouration risk in drinking water distribution systems. To investigate this thesis a study was performed in a drinking water distribution system. In two similar isolated network areas the effect of particles on discolouration risk was studied with particle counting, the Resuspension Potential Method (RPM) and assessment of the total accumulated sediment. In the ‘Control Area’, supplied with normal drinking water, the discolouration risk was regenerated within 1.5 year. In the ‘Research Area’, supplied with particle-free water, this will take 10-15 years. An obvious remedy for controlling the discolouration risk is to improve the treatment with respect to the short peaks that are caused by particle breakthrough.     

室内悬浮颗粒的数值模拟

应用多流体模型和小滑移模型模拟了一个1000级洁净厂房的流场、温度场和颗粒分布,并与实测数据进行了比较,认为在一定条件下多流体模型比小滑移模型更适合模拟洁净室中稀疏悬浮颗粒。     

Probing young drinking water biofilms with hard and soft particles

The aim of our study was to investigate, through the use of soft (Escherichia coli) and hard (polystyrene microspheres) particles, the distribution and persistence of allochthonous particles inoculated in drinking water flow chambers. Biofilms were allowed to grow for 7-10 months in tap water from Nancy's drinking water network and were composed of bacterial aggregates and filamentous fungi. Both model particles adhered almost exclusively on the biofilms (i.e. on the bacterial aggregates and on the filamentous structures) and not directly on the uncolonized walls (glass or Plexiglas). Biofilm age (i.e. bacterial density and biofilm properties) and convective-diffusion were found to govern particle accumulation: older biofilms and higher wall shear rates both increased the velocity and the amount of particle deposition on the biofilm. Persistence of the polystyrene particles was measured over a two-month period after inoculation. Accumulation amounts were found to be very different between hard and soft particles as only 0.03‰ of the soft particles inoculated accumulated in the biofilm against 0.3-0.8% for hard particles.     

Speedy technique of chromatographic determination of toxic metals in drinking water

We have developed a simple fast technique of chromatographic determination of toxic metals Cu. Cd, Co, Ni, Zn, Hg, and Pb in drinking water using thin layer chromatography. The metals were separated in the form of their complexes with dithizone and then photometric detection of obtained spots was carried out.     

Characterisation of the behaviour of particles in biofilters for pre-treatment of drinking water

Biofiltration of surface water was examined using granular activated carbon (GAC) and expanded clay (EC). Particle removal was 60-90%, measured by flow cytometry, which enabled discrimination between total- and autofluorescent particles (microalgae) in size ranges of 0.4-1 and 1-15 microm, and measured by on-line particle counting. Total particles were removed at a higher degree than autofluorescent particles. The biofilters were also challenged with 1 microm fluorescent microspheres with hydrophobic and hydrophilic surface characteristics and bacteriophages (Salmonella typhimurium 28B). Added microspheres were removed at 97-99% (hydrophobic) and 85-89% (hydrophilic) after 5 hydraulic residence times (HRT) and microspheres retained in the biofilter media were slowly detaching into the filtrate for a long time after the addition. Removal of bacteriophages (5 HRT) was considerably lower at 40-59%, and no long-lasting detachment was observed. A comparison of experimental data with theoretical predictions for removal of particles in clean granular media filters revealed a similar or higher removal of particles around 1 microm in size than predicted, while bacteriophages were removed at a similar or lesser extent than predicted. The results highlight the selectivity and dynamic behaviour of the particle removal processes and have implications for operation and microbial risk assessment of a treatment train with biofilters as pre-treatment.     

Effects of ultrasound on suspended particles in municipal wastewater

The objective of this research is to explore the fundamental characteristics of how particles in wastewater respond to ultrasound, with an aim to improve wastewater disinfection. Particles of a predetermined size fraction and concentration were treated with varying doses of ultrasound at 20.3 kHz. Ultrasonic power transfer to the fluid was measured using calorimetry or acoustical measurements. Image analysis particle counting was used to measure the size distribution of particles before and after ultrasound treatment. The influence of three parameters: particle origin (raw wastewater or from the aeration basin of the activated sludge process), particle concentration, and particle size on the percentage of particle breakage after ultrasound treatment was compared. It was found that raw wastewater and aeration basin particles of the same size fraction (90-106 μm) responded to ultrasound in a similar way. Particle breakage was not affected by changes in particle concentration from 100 to 400 particles per mL. Larger wastewater particles (90-250 μm) were more susceptible to breakage than smaller ones (38-63 μm diameter). The percentage of particle breakage increased linearly with a logarithmic increase in the ultrasound energy density, that is the ultrasound energy delivered per unit volume of the sample (R² = 0.48-0.91). An expression that predicts the percent of particles broken as a function of ultrasound energy density is provided.     

Rapid enumeration of virus-like particles in drinking water samples using SYBR green I-staining

We studied the suitability of SYBR green I-staining for determining total counts of virus-like particles and bacteria in drinking water. Low background fluorescence and lack of unspecific staining made drinking water samples an excellent matrix for SYBR green I-staining. Direct microscopic count method is a rapid and economical tool for assessing the total number of virus-like particles in aquatic samples, compared to culture-dependent or molecular biology methods. We applied this method to show the efficiency of a large-scale drinking water purification process in the removal of virus-like particles and bacteria from lake water.     

聚羧酸系减水剂在高性能混凝土中的应用研究

由于天然砂资源逐步短缺,建筑工程大量使用天然细砂与人工砂等混合砂,应用常见的聚羧酸系减水剂难以配制出高性能混凝土.试验研究采用常规混凝土生产工艺,原材料均为有代表性的材料,通过对比不同分子结构的聚羧酸系减水剂的应用性能,说明选用缓释型的新一代聚羧酸系减水剂,可以较好适应建筑工程中黏土质人工砂的使用问题.     

生活饮用水中灭草松2、4,-滴和五氯酚的同时测定

采用高效液相色谱法同时测定生活饮用水中灭草松、2,4-滴和五氯酚。水样经Oasis HLB柱分离富集,用甲醇洗脱,然后经吹氮浓缩后用高效液相色谱法测定。所测得的峰面积与质量浓度在0.2～15 mg/L内线性良好,相关系数均在0.999以上。该方法操作简便快速,灵敏度高,对灭草松、24,-滴和五氯酚的检出限分别为0.000 8,0.001和0.001 mg/L,满足生活饮用水检测要求。