Surface Silanization of Polyethylene for Enhanced Adhesion

Low density polyethylene has been treated using a novel surface treatment process “SICOR” (“SIIane-on-CORona” treated polymer) in order to enhance adhesion with a range of adhesives including polyure-thane, methacrylate and cyanoacrylate. The process comprises two steps, i.e corona discharge followed by application of an organo-functional silane. The incorporation of surface hydroxyl groups onto the polymer surface enables organo-silane to create the hydrogen or covalent bonds with the oxidized polymer surface. The possibility of the creation of these bonds has been investigated using FTIR, XPS and wettability studies. The adhesion enhancement due to the new process is significant. Frequently, the strength increase exceeds 200% compared with the corona discharge treatment and more than 300% compared with LDPE priming using the “Loctite 770” polyolefin primer. The process is shown to be as good as, or better than, plasma treatment in terms of the strength increase following substrate treatment prior to adhesive bonding.     

Development and evaluation of an ultrasonic personal aerosol sampler

Assessing personal exposure to air pollution has long proven challenging due to technological limitations posed by the samplers themselves. Historically, wearable aerosol monitors have proven to be expensive, noisy, and burdensome. The objective of this work was to develop a new type of wearable monitor, an ultrasonic personal aerosol sampler (UPAS), to overcome many of the technological limitations in personal exposure assessment. The UPAS is a time‐integrated monitor that features a novel micropump that is virtually silent during operation. A suite of onboard environmental sensors integrated with this pump measure and record mass airflow (0.5–3.0 L/min, accurate within 5%), temperature, pressure, relative humidity, light intensity, and acceleration. Rapid development of the UPAS was made possible through recent advances in low‐cost electronics, open‐source programming platforms, and additive manufacturing for rapid prototyping. Interchangeable cyclone inlets provided a close match to the EPA PM_2.5 mass criterion (within 5%) for device flows at either 1.0 or 2.0 L/min. Battery life varied from 23 to 45 hours depending on sample flow rate and selected filter media. Laboratory tests of the UPAS prototype demonstrate excellent agreement with equivalent federal reference method samplers for gravimetric analysis of PM_2.5 across a broad range of concentrations.     

Particulate matter chemical component concentrations and sources in settings of household solid fuel use

Particulate matter (PM) air pollution derives from combustion and non‐combustion sources and consists of various chemical species that may differentially impact human health and climate. Previous reviews of PM chemical component concentrations and sources focus on high‐income urban settings, which likely differ from the low‐ and middle‐income settings where solid fuel (ie, coal, biomass) is commonly burned for cooking and heating. We aimed to summarize the concentrations of PM chemical components and their contributing sources in settings where solid fuel is burned. We searched the literature for studies that reported PM component concentrations from homes, personal exposures, and direct stove emissions under uncontrolled, real‐world conditions. We calculated weighted mean daily concentrations for select PM components and compared sources of PM determined by source apportionment. Our search criteria yielded 48 studies conducted in 12 countries. Weighted mean daily cooking area concentrations of elemental carbon, organic carbon, and benzo(a)pyrene were 18.8 μg m^?3, 74.0 μg m^?3, and 155 ng m^?3, respectively. Solid fuel combustion explained 29%‐48% of principal component/factor analysis variance and 41%‐87% of PM mass determined by positive matrix factorization. Multiple indoor and outdoor sources impacted PM concentrations and composition in these settings, including solid fuel burning, mobile emissions, dust, and solid waste burning.     

山西岩溶泉流量衰减成因分析——以辛安泉为例

近年来，我省各岩溶大泉流量在不同程度上均有所下降，文中以辛安泉为例，分析研究其流量衰减原因，采用数学相关模型对辛安泉的流量与大气降雨和人工开采进行了分析，找到了它们与泉流量衰减之间的内在关系，为日后合理开发利用泉水资源提供了指导。     

基于免疫学习的对等网络邻居节点选择方案

文件污染是对等网络共享系统普遍存在的问题,一个好的邻居节点选择方案可以有效抑制污染文件的传播。设计了基于免疫学习的投票相似度计算方法和邻居节点选择方案,并采用自适应的阈值判断文件的可信性。仿真实验表明,本方案抑制了恶意节点传播污染文件的可能性,并具有较小的开销,具有一定的应用价值。     

交直流同塔三回输电线路地面电场的预测分析

基于有限元和有限体积法的混合方法,合理地考虑了直流电晕放电和交流电晕放电之间的相互影响,解决了交直流同塔输电线路地面电场的分布计算问题.通过小尺寸模型的实验了验证计算方法的有效性.针对一回±800 kV直流输电线路和两回500 kV交流输电线路同塔架设的实际情况,计算了不同运行方式下的地面电场的直流分量、交流分量和离子流密度的分布情况.计算结果表明,由于交流输电线路的电晕放电,地面电场直流分量和离子流密度会有所降低.同时,地面交、直流电场均随线路高度的升高而降低,但是工频电场的变化程度比直流电场要大.     

局部放电超高频检测抗干扰与多源放电信号分离方法

变电站的电磁环境复杂,存在大量处于超高频（ultrahigh-frequency,UHV）段内的通讯干扰信号及设备外部的脉冲型干扰信号,导致难以对局部放电故障现场检测结果进行准确的诊断。针对局部放电UHF检测中的抗干扰问题,提出了一种基于波形互相关分析、噪声传感器及幅比聚类分析的局部放电UHF综合抗干扰技术,试验证明这种抗干扰技术可有效排除通讯干扰、设备外部脉冲型干扰,并实现设备内部多放电源辐射的超高频信号的分离与识别,提高局部放电检测与诊断的有效性与准确性。     

老化中压电缆复合界面的放电特性研究

针对中压电缆热缩型中间接头界面受潮老化的放电特性做了相关研究,分别在不同的湿度环境下做了两类中间接头样本。通过对干燥电缆接头和受潮电缆接头界面间的放电特性做了对比,将整个放电过程分成了三个阶段,分别对比这三个阶段的不同放电特征。对击穿后的样本进行了解剖,观测到受潮界面和干燥界面绝缘失效后的电痕有差异。分析了造成放电特性和电痕差异的主要原因。得出了由于界面间水的作用,使得界面空腔被填满的同时降低了绝缘强度,虽然消弱了初始阶段的局部放电,但增加了后期的击穿概率。而造成不同的电痕特征的主要原因在于干燥界面间的放电对绝缘的劣化具有累积效应,所以放电主要集中在一条通道上。而潮湿界面在水的作用下,界面击穿发生在不同的位置,碳化痕迹分布较广。     

突发重金属水污染事故环境风险评价模型研究

为降低我国重金属突发水污染事故发生频率、减轻事故危害,针对目前突发水污染事故环境风险评价缺乏系统性研究的现状,构建了基于蒙特卡洛模拟法的突发水污染事故环境风险评价模型,提出了一套计算突发水污染事故环境风险的方法。该模型由突发水污染事故概率分析模型、重金属迁移转化分相模型、突发水污染事故损失评估模型耦合而成。应用该模型对佛山市的环境风险进行了评价,结果表明:计算时间段为固定值时,重大风险值和特大风险值之和为8%;计算时间段为区间值时,重大风险值和特大风险值之和为21%,说明该地区的环境风险已经十分严峻。     

赣南红壤坡面不同措施径流泥沙及氮磷污染输出试验研究

选择赣南于都县左马小流域的典型红壤坡面,通过在研究区布设标准径流小区,进行了不同措施径流泥沙及氮磷污染输出的试验研究。通过径流小区的试验观测分析表明:水保林+水平竹节沟式综合水保措施实施初期,平均减流和减沙效果达到近73%,以植被增加地表覆盖度,以水平竹节沟坡面水保工程截短坡长,分段拦蓄径流泥沙,可实现保水保土目的;经果林+坡面工程或绿篱是坡地经济果业开发保持水土的重要措施,工程措施在初期发挥作用较绿篱更大;氮磷等面源污染随水土流失从坡面输出,试验区不同措施氮素输出多以径流携带为主,磷素输出均以泥沙携带为主;经果林+工程措施对径流携带氮磷拦截率较高,水保林+工程措施对泥沙携带氮磷的拦截率较高,都在75%以上。