细炻砖铜锈缺陷研究

细炻砖作为仿古砖的一个重要组成部分一直在家庭装修中被广泛应用。在细炻砖的生产过程中,铜锈在浅色版面中容易显露出来,占总缺陷的比例比较大,也降低了产品的品质。本文用XRF对原材料和坯体配方进行了定性分析,用SEM对铜锈进行了表面形貌分析,用EDS对铜锈进行了元素分析。结果表明,铜锈主要是原料中的有色金属杂质引起。通过加强浆料的过筛,降低浆料的细度可以有效减少铜锈的产生。     

Detection of RDX traces at the surface with sonic aerosol flow desorption

The use of a high-speed aerosol flow is proposed for sampling RDX from the surface followed by chromatographic analysis. The aerosol is generated from different solvents by means of a coaxial nebulizer. The effect of the aerosol flow parameters (solvent flowrate, an angle of the nebulizer inclination with respect to the surface) and various solvents (water, acetone, and hexane) on the efficiency of the RDX desorption was investigated. The optimal angle of the nebulizer was found to be 30°, under these conditions, the desorption of RDX from the surfaces of different structure (metal, glass, leather, cotton fabric, and paper) has also been studied. It is shown that under the action of an aerosol created using water and acetone, desorption from a smooth surface occurs most efficiently (1.5 times higher than with hexane). In this case, the sample removes almost completely (about 80%) by the aerosol flow in a few seconds. A relationship between the desorption efficiency and the amount of the solvent sprayed (that is the amount of aerosol particles in desorbing flow) has a characteristic maximum which location depends on the properties of the solvent spray. This effect is associated with a rate of solvent evaporation. Under optimal conditions for desorption of RDX from a smooth surface using an aqueous aerosol, an LOD of ～10?ng can be achieved. For porous and rough surfaces, the efficiency of the analyte desorption decreases (three times for leather and cotton fabric). The results of the experiments conducted allow one to conclude that the RDX solubility in the solvent used does not affect considerably the efficiency of the RDX desorption. It is assumed that small aerosol drops are very active and can capture the particles of the target analyte. This promotes the desorption of RDX molecules from the surface.

© 2018 American Association for Aerosol Research     

Particle capture by a rotating disk in a kitchen exhaust hood

Abstract

Chinese cooking produces large numbers of particles that can cause both indoor and outdoor air quality problems. To reduce the extraction of particles to the outdoor air, this investigation studied capture efficiency of a rotating disk in an exhaust hood. The studies were performed experimentally in a wind tunnel and numerically by computational fluid dynamics (CFD) models with the Lagrangian method for tracking particle trajectories. The experimental data were used to identify the best turbulence model among the three tested in the CFD simulations. The results show that the capture efficiency increased with disk rotation speed and particle size but decreased with exhaust airflow rate. The CFD simulations provided detailed information about the mechanisms by which particles of different sizes were captured by the rotating disk. CFD was then used to explore two methods for improving the capture efficiency: adding more wires to the middle and outer zones of the disk, and using two layers of disks. Both methods can increase the capture efficiency of the rotating disk at an acceptable pressure loss.

Copyright © 2020 American Association for Aerosol Research     

辽宁王营子钼矿地质特征及找矿标志

辽宁省朝阳市王营子钨钼矿位于努鲁儿虎山脉大青山东部,属辽西凌源—北票金成矿带高杖子—大庙—东五家子金成矿区中部,蝴蝶沟—王营子金钼多金属矿化带。研究区内地层、岩浆岩发育较好,构造未见明显特征。主要岩体以斑状花岗岩、似斑状花岗岩为主,矿体严格受似斑状花岗岩控制,富集于钾化似斑花岗岩中,矿脉与围岩无明显界线。基于野外实际勘查、成矿地质条件等的研究,认为王营子钼矿为细脉浸染型斑岩型钼矿,并总结了找矿标志。     

多光谱成像仪几何特征标定技术研究

多光谱成像仪具有同目标多谱段信息获取的特点,因此在空间遥感领域占据很重要的位置。由于成像仪光学系统不可避免的存在几何畸变问题,会对获取地面目标信息的精度造成很大的影响,因此对于多光谱成像仪进行几何特征标定对于提升成像仪成像质量的有很大的作用。本文中应用标准网格板、自准直仪和高精度二维转台组合的几何特征标定方法,此方法具有测量原理简单、实验直观、标定结果可靠性高等特点。多次标定结果表明：主点标定精度优于5.2 μm,主距标定精度优于0.02 mm。满足实验要求。     

《瘗旅文》中王阳明人格境界的解读

王阳明的《瘗旅文》表达了他对逝者的真切同情，显示出一个儒者独特的诗性审美境界；文中言辞及埋葬死者躯体、祭奠亡灵的义举则是一种达人达己的仁者精神；他在文末所秉承“止于悲伤”之达观态度，表现出通变制宜的智者心境。     

Characterization of particle emissions from consumer fused deposition modeling 3D printers

Particle emissions from multiple fused deposition modeling consumer 3D printers were systematically quantified utilizing an established emission testing protocol (Blue Angel) to allow quantitative exposure assessments for printers operating in different environments. The data are consistent with particle generation from volatilization of the polymer filament as it is heated by the extruder. Typically, as printing begins, a burst of new particle formation leads to the smallest sizes and maximum number concentrations produced throughout the print job. For acrylonitrile butadiene styrene (ABS) filaments, instantaneous concentrations were up to 10⁶ #/cm³ with mean particle sizes of 20 to 40 nm when measured in a well mixed 1 m³ chamber with 1 air change per hour. Particles are continuously formed during printing and the size distribution evolves consistent with vapor condensation and particle coagulation. Particles emitted per mass of filament consumed (particle yield) varied widely due to factors including printer brand, and type and brand of filament. Higher extruder temperatures result in larger emissions. For filament materials tested, average particle number yields ranged from 7.3 × 10⁸ to 5.2 × 10¹⁰ g^?1 (approximately 0.65 to 24 ppm), with trace additives apparently driving the large variations. Nanoparticles (diameters less than 100 nm) dominate number distributions, whereas diameters in the range of 200 to 500 nm contribute most to estimated mass. Because 3D printers are often used in public spaces and personal residences, the general public and particularly susceptible populations, such as children, can be exposed to high concentrations of non-engineered nanoparticles of potential toxicity.

Copyright © 2017 American Association for Aerosol Research     

GKP外墙外保温薄抹灰贴面砖的探讨

我国南方应用较广的GKP外墙外保温薄抹灰贴面砖出现大面积开裂、脱落问题较多.作者针对这一现象从施工的角度提出解决方法,以供同行参考.     

秦岭岩白菜多糖的提取纯化工艺研究

以秦岭岩白菜多糖的含量和得率为指标,采用正交实验对秦岭岩白菜多糖的提取纯化工艺进行了优化。确定秦岭岩白菜多糖的最佳提取工艺为：用20 BV水在90℃提取3次,每次0.5 h;最佳纯化工艺为：用4 BV 70％(体积分数)乙醇醇沉24 h。该优化提取纯化工艺简便、合理、可行。     

The 4-way deterministic tiling problem is undecidable

It is shown that the (infinite) tiling problem by Wang tiles is undecidable even if the given tile set is deterministic by all four corners, i.e. a tile is uniquely determined by the colors of any two adjacent edges. The reduction is done from the Turing machine halting problem and uses the aperiodic tile set of Kari and Papasoglu.