Breakthrough Curves Characterization and Identification of an Unknown Pollution Source in Groundwater System Using an Artificial Neural Network (ANN)

Contamination of groundwater constrains its uses and poses a serious threat to the environment. Once groundwater is contaminated, the cleanup may be difficult and expensive. Identification of unknown pollution sources is the first step toward adopting any remediation strategy. The proposed methodology exploits the capability of a universal function approximation by a feed-forward multilayer artificial neural network (ANN) to identify the sources in terms of its location, magnitudes, and duration of activity. The back-propagation algorithm is utilized for training the ANN to identify the source characteristics based on simulated concentration data at specified observation locations in the aquifer. Uniform random generation and the Latin hypercube sampling method of random generation are used to generate temporal varying source fluxes. These source fluxes are used in groundwater flow and the transport simulation model to generate necessary data for the ANN model-building processes. Breakthrough curves obtained for the specified pollution scenario are characterized by different methods. The characterized breakthrough curves parameters serve as inputs to ANN model. Unknown pollution source characteristics are outputs for ANN model. Experimentation is also performed with different number of training and testing patterns. In addition, the effects of measurement errors in concentration measurements values are used to show the robustness of ANN based methodology for source identification in case of erroneous data.     

高分子材料服役寿命预测方法最新进展

高分子材料在使用过程中,由于受各种环境因素作用,会逐步出现性能下降,甚至丧失使用价值的老化现象,不仅造成资源浪费,更形成安全隐患。为应对老化问题,研究者以各种宏观性能或微观结构、组份的变化来表征老化过程,针对高分子材料的环境适应性开展了大量研究工作,并在此基础上提出了不同的老化机理和服役寿命预测方法。从高分子材料老化过程表征的视角,综述了近年来高分子材料服役寿命预测方法的最新进展。     

国外生命周期影响评价中酸化模型的方法概述

生命周期影响评价是生命周期评价的重要组成部分,而其中的特征化过程是实现定量评价的关键步骤。酸化（Acidification）是生命周期影响评价（LCIA）中最为普遍的影响类型之一,指由酸性气体排放引起生态环境破坏以及人体健康的损害。欧洲、北美、日本等发达国家都建立了自己的生命周期影响评价体系,本文分析了这些地区存在的酸化模型方法,对建立中国的生命周期评价数据库具有重要的意义。     

水体黑臭及表观污染表征方法的研究进展

本文提出了水体表观污染的概念,指出水体的表观污染就是水体的某些表观特征引起人们感官不悦的现象。综述了前人对水体黑臭的表征方法,总结出了判别水体黑臭的各种阈值和指数关系式,并做了比较指出不足。明确了建立一套科学的、客观的、稳定的水体表观污染表征方法的必要性。     

单臂冠醚—金属卟啉配合物的合成与表征

利用磺酰氯键将苯并15-冠-5和5-(2-羟基苯基)- 10,15,20-三(4-硝基苯基)交联,合成了单臂冠醚一卟啉配体(CNTPP)及其金属配合物(CNIPPMn和CNTPPCo).通过红外光谱、紫外吸收光谱与光电子能谱对化合物和配合物进行结构分析表明,在489cm-1和480cm-1出现M-N键的吸收蜂,在1360cm-1和1363cm-1处有S=O键吸收峰.配位中心离子进入卟啉环后引起配合物CNTPPM分子的对称性提高,使Sorct带发生位移,且N原子与金属离子形成配位键后,其中一对N电子结合能升高,另外一对N原子下降,且导致配合物中M2p3/2的电子结合能变大.     

Zn/Cr型阴离子黏土的制备、表征及其对活性艳橙X-GN的去除性能研究

采用共沉淀法制备了Zn/Cr摩尔比为1∶1～5∶1的Zn/Cr型阴离子黏土(Zn/Cr-LDHs),选取2∶1 Zn/Cr-LDHs分别在300、400、500℃条件下放入马弗炉中煅烧2 h,制备了煅烧阴离子黏土(Zn/Cr-LDO).采用X射线衍射光谱(XRD)、傅里叶红外光谱(FTIR)、原子吸收法(ASS)、比表面积测试法(BET)对上述制备的材料结构形态进行表征.研究2∶1 Zn/Cr-LDHs和Zn/Cr-LDO在紫外和避光条件下对活性艳橙X-GN的去除.实验表明,2∶1 Zn/Cr-LDHs的吸附效果不受紫外光照射的影响,煅烧后形成的Zn/Cr-LDO在紫外光的照射下,对活性艳橙X-GN的去除率是避光条件下的2倍,说明煅烧后的Zn/Cr阴离子黏土具有光催化性能,Zn/Cr-LDO对活性艳橙X-GN的去除是吸附和光催化的共同作用.     

Experimental investigation on mechanical and metallurgical properties of super duplex stainless steel joints using friction welding process

Friction welding is one of the most economical and highly practicable methods in joining similar and dissimilar metals. In this study, high-quality welds are produced in the super duplex stainless steel by continuous drive friction welding successfully. Design of experiment was done using central composite design of response surface methodology. In the present work, the microstructure and mechanical properties of friction welded super duplex stainless steel (UNS S32760) were examined. The base material has a microstructure consisting of the ferrite matrix with austenite islands. Ferrite content was analyzed through the phase analyzer software and found that it is in the range of 42–55% in all weld metals. The phases were further analyzed through X-ray diffraction method. All the weld metals have higher hardness than the base metals. Weld transverse tensile failures consistently occurred away from the weld zone and exhibit more hardness, yield and ultimate tensile strengths than the base material. The austenite content increases with nitrogen concentration. Nitrogen could enhance the yield stress and ultimately tensile strength of super duplex stainless steel. Secondary phase precipitation is not observed in the welded joint probably due to the shorter heating times.     

玉米根内和根际土壤溶磷细菌生物学特性研究

从玉米根内和根际土壤中分离筛选到22株溶磷细菌。根据16SrRNA基因序列分析,2株溶磷效果最好的菌株分别被鉴定为伯克霍尔德氏菌(Burkholderia sp.SY9)和泛菌(Pantoea sp.Gym7c)。同时对菌株SY9和Gym7c的溶磷能力和植物促生特性进行了进一步研究。利用磷酸钙和开阳磷矿矿粉研究了菌株释放P、Ca和Fe的效能。液体培养条件下,菌株在在磷酸钙培养基中的生长好于在开阳磷矿粉培养基中的生长,同时菌株能够合成铁载体。菌株SY9从开阳磷矿粉中释放P、Ca,和Fe的能力比菌株Gym7c强。然而菌株Gym7c从磷酸钙中释放P和Ca的能力比菌株SY9强。菌株Gym7c主要是通过合成的有机酸溶解磷酸钙并释放其中的P和Ca,而菌株SY9是通过合成的有机酸和铁载体溶解开阳磷矿粉并释放出其中的P、Ca,和Fe。溶解开阳磷矿粉的有机酸主要是葡萄糖酸而溶解磷酸钙的有机酸主要包括丁二酸、丙酸、苹果酸和酒石酸等。菌株Gym7c能够合成生长素、铁载体和1-氨基环丙烷-1-羧酸脱氨酶。菌株SY9和Gym7c对酸碱、盐和温度均表现出一定的抗性。     

改性成都粘土预处理垃圾渗滤液的研究

文章采用十六烷基三甲基溴化铵(HDTMA)、丙烯酰胺(AM)和聚合氯化铝(PAC)3种改性剂分别对成都粘土进行改性,将改性粘土用于垃圾渗滤液处理,比较不同改性粘土对氨氮和COD的吸附性能,并通过X射线衍射、红外光谱、热分析技术对改性粘土进行表征,分析作用机理;研究表明,粘土经过改性后,3种改性粘土的底面间距分别增大0.7533、0.3496、0.1929nm,对垃圾渗滤液中氨氮和COD去除效果关系为:HDTMA改性土>AM改性土>PAC改性土>原土,HDTMA改性土为最优改性土。改性粘土预处理渗滤液方法是可行的,HDTMA改性土是最优改性土,对氨氮去除率达到48.68%,COD去除率达到32.27%,控制条件为:投加量为100g,pH=7,转速为200 r/min(50min),静置时间6h。     

整体式分子筛基催化剂制备及其微波催化燃烧VOCs

以整体式蜂窝状分子筛为载体,制备铜锰铈负载型催化剂,研究其微波辐照下对VOCs （甲苯、丙酮、乙酸乙酯）的催化活性及其稳定性,探究影响催化剂活性的因素,并通过测试床层温度分布进行分析.研究表明,微波功率1.3kW、催化剂体积300mm×300mm×300mm,固定床温度>300℃条件下,催化剂对初始浓度200~2000mg/m³的5m³/h VOCs气体的降解效率为80%~92%.温度是VOCs氧化降解的条件,但当床层温度超过了300℃（VOCs完全燃烧温度）之后,升温对VOCs降解效率的影响不再明显.表征可知,尖晶石态铜锰铈单金属氧化物及其复合氧化物是主要的催化活性组分.VOCs在催化剂表面进行准一级反应而被催化氧化;高温对催化剂结构有一定影响,但重复性试验证实了催化剂的高活性和良好的稳定性.