Sex Pheromone of Nuttall's Sheep Moth, Hemileuca nuttalli, from the Eastern Sierra Nevada Mountains of California

The sex attractant pheromone blend of Hemileuca nuttalli (Lepidoptera: Saturniidae) from the eastern slope of the Sierra Nevada Mountains in California was determined to be a combination of E10,Z12-hexadeca-10,12-dien-1-yl acetate (E10,Z12–16:Ac) and E10,E12-hexadeca-10,12-dien-1-yl acetate (E10,E12–16:Ac). Ratios of the compounds in extracts of female pheromone glands varied around a mean of 100:48, although the ratio was not critical in field trials. Blends of synthetic E10,Z12–16:Ac and E10,E12–16:Ac in 100:50, 50:100, and 100:100 ratios attracted equal numbers of male moths. Field trials also indicated that E10,Z12–hexadeca-10,12-dien-1-ol (E10,Z12–16:OH) and E10,Z12-hexadeca-10,12-dienal (E10,Z12–16:Ald) were antagonistic at rates of 3.3% and 10%, respectively, of the E10,Z12–16:Ac, despite being found in female moth extracts. E10,E12–16:Ac, E10,Z12–16:OH, and E10,Z12–16:Ald all appear to have roles in maintenance of reproductive isolation between H. nuttalli and H. eglanterina.     

用于细颗粒分离的水力旋流器的压力特性研究

对用于细颗粒分离的水力旋流器的压力特性 (压力降及压降比 )与流量、分流比、旋数、溢流口和底流口直径及气液比等主要参数之间的关系进行了深入的研究与分析。研究发现 ,水力旋流器内部压力降分别随流量、分流比、旋数及气液比的提高而加大 ,压降比则分别随流量、分流比、旋数的提高而降低。随着溢流口直径的加大 ,水力旋流器的溢流压力降减小 ,而压降比也随之降低 ;随着底流口直径的加大 ,底流压力降减小 ,压降比随之升高。分析可知 ,减少旋流器能耗的有效方法是降低旋数 ,或者减少混合介质中的气液比     

Characteristics of a NaOH-Activated Blast Furnace Slag Blended with a Fine Particle Silica Waste

Mortars of blast furnace slag blended with a geothermal silica waste at various replacement levels of 0%, 5%, 10%, 15%, and 20% were cured for up to 90 days. The binder was activated by 6 wt% Na₂O equivalent of sodium hydroxide. Lime was added as an activating agent and also to promote pozzolanic reaction with the silica. It was found that the presence of the silica waste increased the reactivity of the cementitious materials, as measured by means of nonevaporable water. The compressive strength was increased in the presence of the silica, except at the highest replacement level of 20%, the optimum silica replacement was that of 5%–10%. The microstructures of blended slag showed less porosity than those of neat slag mortars. The lime was completely consumed after 90 days of hydration.     

Fine Particle Behavior in the Air Flow Past a Triangular Cylinder

This study investigates the fine particle behavior in the laminar airflow past a triangular cylinder. To track particles in motion for the investigation, a visualization system integrated with an effective postprocessing method is developed. Then it is perhaps for the first time that several individual fine particles moving in the flow near the base corners of the cylinder are tracked both simultaneously and continuously. These particles are found to follow closely the airflow pathlines, except very near the corners where the microscopic Stokes number is high. It is also revealed that all the particle tracks vacillate discernibly due to the Brownian motion. Taking this into account, an improved numerical simulation is conducted based on CFD software package FLUENT, with which dithering tracks of the moving particles are reproduced.

Copyright 2013 American Association for Aerosol Research     

Measurement of the Size of Fine Nonspherical Particles with a Light-Scattering Particle Counter

To characterize flow separation and classification processes, particle size distributions must be measured in the airborne state without affecting the state of dispersion or disturbing the flow. Light-scattering devices with an optically defined measuring volume are specially designed for this purpose. However, the light-scattering device must be calibrated using nonideal particles which are present within the multiphase flow, preferably on an equivalent diameter based on settling rate. The cyclone cut size calibration can solve this problem. By means of this aerodynamic calibration technique, it is possible to measure size distributions of nonspherical particles with a light-scattering particle counter in industrially relevant cases.     

广州市大气细颗粒物及微量元素的分析

在广州市区采集大气细颗粒物PM2．5样品,对PM2．5及其中12种微量元素进行分析。研究结果显示采样期间广州市大气PM25的平均浓度为113．3μg／m3,远远超过了美国EPA制定的PM25日均浓度限值（35μg／m3）。与国内外其它大城市相比,PM2．5中微量元素的浓度处于较高水平,其中重金属元素Cd、Pb、Zn、Cu、As、Ni、M0、Mn、Cr和Co的富集因子EF远远大于1,主要来源于人为污染·     

Influence of Polymeric Suspension Characteristics on the Particle Coating in a Spouted Bed

Abstract

The influence of the coating suspensions and particle properties on the coating process in a conventional spouted bed is presented. Glass beads were coated at fixed operating conditions with different formulations of aqueous polymeric coating suspensions in a spouted bed of laboratory scale. The wettability of the solids by the liquid was quantified by the contact angle and surface tension of the coating suspensions. The coating efficiency and particle growth were correlated with the adhesion of the coating suspension to the solid particle, which is a function of the solids and liquid characteristics. The physical properties of the coated particles—particle mean diameter, sphericity, bulk, absolute and apparent densities, porosity and flow velocity—were determined and compared to the properties of uncoated particles.     

Influence of Polymeric Suspension Characteristics on the Particle Coating in a Spouted Bed

The influence of the coating suspensions and particle properties on the coating process in a conventional spouted bed is presented. Glass beads were coated at fixed operating conditions with different formulations of aqueous polymeric coating suspensions in a spouted bed of laboratory scale. The wettability of the solids by the liquid was quantified by the contact angle and surface tension of the coating suspensions. The coating efficiency and particle growth were correlated with the adhesion of the coating suspension to the solid particle, which is a function of the solids and liquid characteristics. The physical properties of the coated particles—particle mean diameter, sphericity, bulk, absolute and apparent densities, porosity and flow velocity—were determined and compared to the properties of uncoated particles.     

火焰法合成纳米TiO2颗粒生长过程

在新型火焰反应器生产纳米TiO2的过程中使用TEM微栅在不同火焰高度位置处进行原位取样分析,得到生长过程中纳米TiO2颗粒的粒径和形态. TiO2颗粒经历了成核、生长、聚并、烧结的过程. 调节反应物浓度为7.9×10-5~5.7×10-3 mol/L,研究了不同反应物浓度对纳米颗粒生长过程的影响,高前驱体浓度形成较高的单体浓度,使颗粒间碰撞几率增加,从而得到粒径较大的颗粒,产物粒径17~85 nm. 调节CH4和O2流量,改变温度场,研究温度对颗粒生长过程的影响,在相同反应物浓度条件下,较高的温度下形成分散性好、一次粒径为63 nm的颗粒,而在较低的温度下形成的颗粒一次粒径为35 nm,但颈部烧结严重;增加喷嘴气流速度减小了反应停留时间,颗粒粒径从63 nm减小到36 nm.     

石化企业细颗粒污泥分离用旋流器的设计与优选

针对粒径中值低于50μm的油田细颗粒污泥较难处理的现状,设计并优选了一种适用于细颗粒分离用的固液旋流器。室内试验表明,设计并优选得到的主直径50mm、溢流口径12mm、锥角5度的固液旋流器在其工作流量3．2～3．6m^3／h内,可以针对粒径中值50μm以下的细颗粒污泥达到较好的分离效果。采用旋流器处理细颗粒油田污泥切实可行。     

固-液导流筒搅拌槽内流体流动和颗粒悬浮特性

在直径0.8 m的导流筒搅拌槽内,对单相液体的三维速度分布、固-液两相的固体颗粒浓度分布和离底悬浮特性进行了系统的实验研究. 结果表明,导流筒内外的轴向液相速度远大于径向和切向速度,导流筒外壁附近存在一个与主体轴向流动方向相反的二次流区域;搅拌槽底部结构对固体颗粒的临界离底悬浮转速(NJS)有显著的影响,浅锥底的NJS比平底的低14%以上;NJS随固相浓度的增加而增加,但当浓度超过50%时,NJS略有降低;槽内固相浓度分布的均匀性随固相浓度的增加而得到改善. 本研究结果对导流筒搅拌槽的优化设计具有一定的指导意义.     

固-液导流简搅拌槽内流体流动和颗粒悬浮特性

在直径0．8m的导流筒搅拌槽内，对单相液体的三维速度分布、固-液两相的固体颗粒浓度分布和离底悬浮特性进行了系统的实验研究．结果表明，导流筒内外的轴向液相速度远大于径向和切向速度，导流筒外壁附近存在一个与主体轴向流动方向相反的二次流区域；搅拌槽底部结构对固体颗粒的临界离底悬浮转速（NJS）有显著的影响，浅锥底的NJS比平底的低14％以上；NJS随固相浓度的增加而增加，但当浓度超过50％时，NJS略有降低；槽内固相浓度分布的均匀性随固相浓度的增加而得到改善．本研究结果对导流筒搅拌槽的优化设计具有一定的指导意义．     

Plasma Oxidation of a Titanium Electrode in dc-Plasma Above the Water Surface

Plasma oxidation of a titanium electrode above liquid water was investigated to reveal the interaction between metallic titanium and plasma above liquid water. Dc-plasma was generated between the titanium and water electrodes. When the titanium electrode was set as anodal, a thick rutile layer was formed on the surface. We had reported previously that the layer showed the preferred orientation along 〈110〉normal to the surface. The degree of the preferred orientation showed a maximum of 0.8 at the electrode temperature of 1073 K. When the titanium electrode was set as cathodal, a plume was generated with the temperature rise because of the bombarding effect of cationic species in the plasma. The collected particles were spherical and were identified as anatase with a small amount of rutile. Optical emission spectroscopy suggested that an oxide layer (TiO₂) firstly formed on the Ti cathode surface, and then vaporization took place with the temperature rise. The spherical anatase particles were formed from the TiO₂ vapor through the rapid cooling.     

Simulation of Drying Characteristics of Evaporation from a Wet Particle in a Turbulent Pulsed Opposing Jet Contactor

The motion and drying characteristics of a single particle in a novel two-dimensional pulsed opposing jet contactor (POJC) are modeled and discussed. Hot air is used as the drying medium. To simulate particle drying, the gas phase and dispersed phase conservation equations are considered in the Eulerian reference frame and the Lagrangian reference frame, respectively. The RNG turbulence model is used to determine the turbulent characteristics of the gas phase. The particle motion is described by the BBO (Basset-Boussinesq-Oseen) equation. The effects of the key parameters, such as the jet Reynolds number, amplitude of pulsation, frequency of pulsation, particle diameter, location of release of particle from one jet as well as velocity profile on residence time (RT) and particle penetration depth (PN) into the opposite jet, are examined. Results show that POJC has strong potential for particulate heat transfer as well as drying; it can improve evaporation rate relative to the corresponding steady OJC by up to 30% as a result of increased residence time in the impingement zone within the parameter ranges simulated.     

Hydrodynamic Characteristics of a Powder‐Particle Spouted Bed with Powder Entrained in Spouting Gas

Spouting of 3.7 mm polyvinyl chloride particles in a cone‐based cylindrical column is subjected to entrainment of FCC powder in the spouting air. It is found that the powder entrainment reduces the minimum spouting velocity, increases the bed pressure drop and reduces the maximum spoutable bed height. At any given bed height and value of U/U_ms, there is a critical value of powder loading ratio above which spouting gives way to slugging.     

Influence of the Metal Particle Size on the Crack Growth Resistance in Mullite–Molybdenum Composites

The R -curve for mullite–molybdenum (32 vol%) composites, which were obtained at 1650°C under reducing conditions with three different Mo average grain sizes (1.5, 3, and 9 μm), was estimated by the indentation-strength method and compared with that monolithic mullite obtained under similar conditions. The composites material exhibited rising R -curve behavior. The composite with larger grain size, however, displayed better damage tolerance and higher resistance to crack growth. Microscopic observation of the crack path revealed, in the composites, the systematic presence of dispersoids acting as bridging sites in the crack wake. Therefore, the increased fracture toughness of these ceramic-matrix composites with adherent ductile phase can be attributed to clamping forces applied by metal ligaments that bridge the crack faces behind the crack front. These clamping forces retard the crack from opening as an external stress is applied. It was inferred that this superior performance of the larger Mo particle size composite can be attributed mainly to more effective bridging of the metal grains. Because of this, a higher applied stress intensity will be required to propagate the crack tip. These results suggest that the rising R -curve should be proportional to the metal grain size, since the grain bridging area is proportional to the metal grain size.     

基于LED光源反射的液固搅拌槽中颗粒悬浮特性测定的光纤法

提出一种基于LED光源反射的液固搅拌槽中固体颗粒悬浮特性测定的光纤法. 在直径0.38 m、底部为椭圆形的搅拌槽中,用该法对水-二氧化硅两相体系固体颗粒悬浮特性进行了测定. 结果表明,测量临界离底悬浮转速Njs的测量点应选择在搅拌槽下部区域,径向位置对Njs影响不大;在整个固含率范围内,光纤测量法与取样法测量结果较接近,平均相对误差为4.0%,目测法测定结果比取样法与光纤测量法稍高,光纤法比取样法更快速、简便,具有适用于不透明容器的优势,能快速测定最小均匀悬浮转速Nus,Nus随固含率增大而增大.     

上浮颗粒特性对三相搅拌槽内固-液悬浮及气-液分散的影响

在直径为0.476m(T)的椭圆底有机玻璃搅拌槽中,采用作者此前研究优选的多层组合桨(HEDT WHD WHU),分别选用粒径在0.5至4mm、密度范围在900至955kg(m(3的聚丙烯(PP)颗粒及粉料、低密度聚乙烯(LDPE)颗粒、高密度聚乙烯(HDPE)颗粒作为上浮固体,操作液位为1.5～1.8T,研究了颗粒特性及操作液位对空气-水-上浮固体三相体系的固-液悬浮及气-液分散性能的影响.结果表明:对于同种颗粒,其表面状态对悬浮特性有较大的影响,颗粒表面因含有少量残余溶剂而呈现部分憎水特性时,达到液面处颗粒停留时间不大于1～2秒的临界悬浮状态所需搅拌转速及输入功率显著增加;此时减少上层桨与液面的距离对降低临界悬浮转速及功率有较大贡献.当颗粒种类不同,表面状态及粒径相近时,液固密度差越大,所需悬浮转速越高;但相同输入功率及表观气速时的气含率相差不大.液固密度差相近时,颗粒越小越易被悬浮,但颗粒越小浓度增加使三相体系的气含率降低的幅度越大.对于不同颗粒所得气含率关联式及悬浮特性研究结果可为工业气液固搅拌槽/反应器的优化设计提供参考.     

气固流化床内宽筛分硅粉颗粒流化特性的数值模拟

为了探索气固流化床内宽筛分硅粉颗粒的流化特性,作者利用计算流体力学CFD软件,采用Eulerian气固多相流模型及SIMPLE算法,模拟了二维气固流化床内不同粒级硅粉颗粒在不同操作件下的气固流化特性;分析了气泡生成、长大和破裂的过程,研究了床内气固两相的流动特性.结果表明:模拟计算值与实验值吻合较好,最大相对误差为10...