Mechanical recycling of EOL concrete into high-grade aggregates

Recycling End of Life (EOL) concrete into high-grade aggregate for new concrete is a challenging prospect for the building sector because of the competing constraints of low recycling process cost and high aggregate product quality. A further complicating factor is that, from the perspective of the environment, there is a strong societal drive to reduce bulk transport of building materials in urban environments, and to apply more in situ recycling technologies for Construction & Demolition Waste. The European C2CA project investigates a combination of smart demolition, grinding of the crushed concrete in an autogenous mill to increase the liberation of cement mortar from the surface of aggregates and a novel dry classification technology called ADR to remove the fines. The feasibility of this recycling process was examined in a demonstration project involving 20,000 tons of EOL concrete from two office towers in Groningen, the Netherlands. Results show that the +4 mm recycled aggregate compares favorably with natural aggregate in terms of workability and the compressive strength of the new concrete, showing 30% higher strength after 7 days.     

车载接地装置的冲击接地阻抗研究

为解决车载装置在不同路面的接地问题,我们研制了可迅速安装和撤收的便携式接地装置,并选取一种组合在不同岩土介质地面上进行了实验,测得各自的冲击接地阻抗。然后,采用时域有限差分法对实验装置进行了数值分析,得出了该接地装置冲击接地阻抗的时域特性。与实验结果进行对比的结果表明,两者具有较好的一致性。     

基于BP神经网络的天线识别

本文比较研究了BP神经网络中的几种常用算法,针对这些不同算法下的BP神经网络进行训练,并得出了各自网络的性能。在此基础上,针对经典BP算法和LM算法进行对比研究,找到LM算法的改进之处。此外,在实际的应用中表明,不仅不同的BP算法对网络的运算速度、泛化能力等有较大的影响,而且BP神经网络对隐含层神经元数目也很敏感。我们希望在BP神经网络的基础上,构建一种合适的天线模型,来应用于天线的分类识别,这将具有很大的现实意义。     

Management of used lead acid battery in China: Secondary lead industry progress,policies and problems

The amount of used lead acid batteries rises along with the rapid development of battery manufacture in China. The battery manufacture and recycling industry has developed sharply in these recent 5 years. The annual production of secondary lead from used lead acid batteries in China increased rapidly to 1.5 million tonnes (MT) in 2013, making china the world's largest secondary lead producer. Secondary lead enterprises are mainly located in the middle and eastern regions of China, with a legal production capacity of 3 MT/year. Environmental pollution problems began to happen frequently from 2009. After 2011, the government began to put in efforts to promote pollution control, eliminate outdated production capacity, support advanced production and technology innovation research, and has achieved remarkable results. However, the main existing problems are that the proportion of secondary lead production is only 30% of the total lead production, no formal recycling network has been established and the overall level of industrial technology and equipment is outdated. Compared with developed countries, this paper predicts that, secondary proportion will reach 44% in 2015 and 60% in 2028. Finally some countermeasures are given to the recycling mode and technology promotion.     

民航空中交通管制设施雷电防护的特点

主要结合多年民航系统设备设施的雷电防护建设实践,在符合国家和民航局相关规定、技术规范的前提下,理论结合实际说明民航通信、导航、监视设施雷电防护的特点。     

榆林地区植被时空分异特征及其影响因素研究

植被作为反映陆地生态系统和气候的重要指标,对研究全球或区域生态环境变化具有重要作用.以地处黄土高原生态脆弱区的榆林市为研究区,基于地理探测器模型,选取坡向、坡度、气温、降水和土壤类型5类自然因子,土地利用类型、人口密度和GDP 3类人文因子,分析榆林地区植被空间分异特征及其驱动力,并揭示了促进植被生长影响因子的最适宜特...     

Molecularly imprinted polymer for analysis of trace atrazine herbicide in water

A molecularly imprinted polymer (MIP) for atrazine was synthesized by non-covalent method. The binding capacity of MIP was 1.00 mg g^{? 1} polymer. The selectivity and recovery were investigated with various pesticides which are mostly, found in the environment, for both similar and different chemical structure of atrazine. The competitive recognition between atrazine and structurally similar compounds was evaluated and it was found that the system provided highest recovery and selectivity for atrazine while low recovery and selectivity were obtained for the other compounds. The highest recovery was obtained from MIP compared with non-imprinted polymer (NIP), a commercial C₁₈ and a granular activated carbon (GAC) sorbent. The method provided high recoveries ranged from 94 to 99% at two spiked levels with relative standard deviations less than 2%. The lower detection limit of the method was 80 ng L^{? 1}. This method was successfully applied for analysis of environmental water samples.     

Toxicity of carbaryl,diquat dibromide,and fluoranthene,individually and in mixture,to larval grass shrimp,Palaemonetes pugio

This study examined the toxicity of two pesticides (carbaryl and diquat dibromide) and one polycyclic aromatic hydrocarbon (fluoranthene), both singly and in mixture, to grass shrimp larvae (Palaemonetes pugio). These three chemicals are all present in coastal environments and can easily enter estuarine ecosystems. Fluoranthene was the most toxic chemical with a 96-h LC₅₀ value of 32.45 μ g/L, followed by carbaryl (43.02 μ g/L) and diquat dibromide (1624 μ g/L). In the chemical mixture tests, the binary carbaryl/diquat dibromide mixture and the ternary carbaryl/diquat dibromide/fluoranthene mixture had additive results.     

退浆废水中聚乙烯醇的分析检测研究

建立了紫外可见分光光度法检测退浆废水中聚乙烯醇(PVA)含量的方法。以硼酸为介质,碘化钾—碘溶液为显色剂,检测波长为680 nm,测定退浆废水中PVA含量的线性方程为Y=0.018 8X+0.003 2,相关系数R2=0.999 3,平均加标回收率为97.6%;方法精密度(RSD=1.5%)、重现性(RSD=1.8%)均较好。该方法操作简单、准确度高、测定快速,适用于测定退浆废水中PVA的含量。