南黄海南部海域表层沉积物重金属来源解析及风险评价

基于2012年夏季对南黄海南部海域的调查资料,分析了表层沉积物中7种重金属元素的含量分布特征;采用多元统计分析,揭示了研究区表层沉积物重金属污染的主要来源及各元素之间的相关性;应用地质累积指数法和Hakanson潜在生态风险指数法对重金属元素进行了污染及风险分析.结果表明:Cd、Pb的含量均符合国标规定的一类沉积物标准,Zn、Cu、Cr在绝大部分站位也都低于国标规定的一类沉积物的最高标准,仅在个别站位处达到二类或三类沉积物标准;除Cr、Cd、Mn外,其余各重金属与Al2O3、平均粒径之间有显著的相关性,表明它们均以自然来源为主,并受到沉积物粒度的控制,遵循"元素的粒度控制律";Cr、Cd、Mn与Al2O3的相关系数较小,表明其可能受到人为污染源的影响.通过主成分分析和聚类分析可将7种重金属元素辨识为2个主成分,PC1(Zn、Cu、Pb、Fe、Mn)为自然源因子,PC2(Cr、Cd)为工农业源因子;其中,Cr、Cd在PC1和PC2上均具有一定的正载荷,受自然地质背景和人类活动的共同控制.地质累积指数法评价结果表明,Zn、Cu、Cd、Pb整体均处于清洁级别,而Cr则处于轻微污染水平,污染程度排序依次为CrPbCdZnCu;潜在生态风险评价结果表明,各元素潜在生态危害等级排序依次为CdPbCuCrZn,Cr、Zn、Cu和Pb均为低生态危害等级,Cd以低中等生态危害等级为主,局部出现较重生态危害等级,综合潜在生态风险评价为低度.     

A new method for the prediction of flash points for ternary miscible mixtures

The flash point is one of the most important physicochemical parameters used to characterize the fire and explosion hazard for flammable liquids. The flash points of ternary miscible mixtures with different components and compositions were measured in this study. Four model input parameters, being normal boiling point, the standard enthalpy of vaporization, the average number of carbon atoms and the stoichiometric concentration of the gas phase for mixtures, were employed and calculated based on the theory of vapor–liquid equilibrium. Both multiple linear regression (MLR) and multiple nonlinear regression (MNR) methods were applied to develop prediction models for the flash points of ternary miscible mixtures. The developed predictive models were validated using data measured experimentally as well as taking data on flash points of ternairy mixtures from the literature. Results showed that the obtained average absolute error of both the MLR and the MNR model for all the datasets were within the range of experimental error of flash point measurements. It is shown that the presented models can be effectively used to predict the flash points of ternary mixtures with only some common physicochemical parameters.     

The Integration of a Genetic Programming-Based Feature Optimizer With Fisher Criterion and Pattern Recognition Techniques to Non-Intrusive Load Monitoring for Load Identification

Identification of electricity energy consumption on individual household appliances used in a smart house is the first important step for making the use and conservation of electricity energy more efficient. In the past, Non-Intrusive Load Monitoring (NILM) techniques, which are part of smart grid techniques realized to improve electricity energy usage efficiency, have been developed to identify individual appliances with avoiding installing many smart meters for appliances in a field. In this paper, a new NILM technique that integrates an efficient Genetic Programming (GP)-based feature optimizer with pattern recognition techniques is proposed to identify which appliance is being turned on or off. The proposed GP-based feature optimizer with Fisher criterion is used to generate a more efficient feature than original potential transient features extracted from captured transient response of household appliances through analysis of NILM. The new feature generated by GP is used by pattern recognition techniques as load identifiers for load identification. The load identifiers used and compared in this paper include k-Nearest-Neighbor Rule, Back-Propagation Artificial Neural Network, and Learning Vector Quantization. Experiments are conducted under different single-load and multiple-load operation circumstances at different actual experimental environments with small disturbances. As shown from the experimental results, the proposed is confirmed to be feasible and usable.     

“一带一路”地区百余年地震时空演变特征

本研究基于“一带一路”地区1900-2018年间≥5级地震事件空间数据,采用小波周期与热区识别方法,分析了该地区地震灾害的空间分布格局与时间周期性特征,并识别了地震灾害空间热区及其演变特征。研究表明:(1)1900-2018年,“一带一路”地区地震发生频次表现出波动性上升的“三段式”分布,主要发生在亚欧大陆-喜马拉雅山周围的亚欧板块与印度洋板块的交界处以及俄罗斯东部沿海、印度尼西亚东南部的环太平洋地区;(2)地震频发地区和震级较强地区均具有多时间尺度的周期变化特征,及一定的空间聚集性,并逐渐演变成高发热区和高强热区;(3)中国和印度尼西亚发生频率远高于其他国家,而缅甸、孟加拉、马尔代夫等国发生频次较低,但其震级强度相对较大。研究结果提示我们未来针对“一带一路”地区基础设施的投资应适当规避地震频发地区及未来潜在的高强热区,同时加强国际间减灾防灾合作,从而更好的降低或预防“一带一路”地区基础设施建设的地震灾害风险。     

南京市4个污水处理厂的活性污泥中细菌的分离鉴定和抗生素耐药性分析

通过16S rDNA序列分析对南京CN、CE、JN和JM这4个污水处理厂的活性污泥中分离的细菌进行鉴定,采用Kirby-Bauer纸片琼脂扩散法分析细菌的抗生素耐药性,目的是阐明该地区污水处理厂活性污泥中细菌抗生素耐药性现状,探索污水及污泥的潜在环境风险.4个污水处理厂分别分离到7、9、8和11株菌落形态不同的细菌,上述35株细菌分属25个种,17个属.抗生素耐药性分析显示,97.1%的菌株具有抗生素耐药性,80%菌株具有多重耐药性.分离菌株对氨苄西林、卡那霉素、氯霉素、链霉素、庆大霉素、四环素、红霉素和大观霉素的耐药率分别为71.4%、37.1%、37.1%、57.1%、34.3%、68.6%、94.3%和65.7%.结果表明活性污泥中细菌耐药性严重;不同菌株间的耐药性分析显示,危害水产养殖业的病原菌气单胞菌具有严重的多重耐药性,所有芽孢杆菌对氯霉素、链霉素和庆大霉素敏感;污水处理厂应加强出水的消杀工作,避免二次污染.     

Influence evaluation of ionic liquids on the alteration of nitrification waste for thermal stability

Nitrification waste (NW) is the processed product of nitro compounds, flammable and explosive, and is prone to accidents due to thermal runaway. Ionic liquids (ILs) are widely used as flame retardants and have a good inhibitory effect. The effect of 1-butyl-3-methylimidazole hexafluorophosphate and 1-butyl-3-methylimidazole tetrafluoroborate as humectants on the thermal stability of NW was investigated in this paper. The microstructure and properties of the ionic liquid hybrid NW were first investigated using scanning electron microscopy. Secondly, thermogravimetric experiments were carried out on the ionic liquid mixed NW by thermogravimetric-infrared spectroscopy to analyze the decomposition law. Finally, six advanced linear regression thermokinetic models were used to calculate its apparent activation energy, pre-exponential factor, and other thermokinetic parameters, and the reaction model was simulated through multiple linear regression. The experimental research results in this paper can provide a reference for the storage and disposal of nitro compounds and their wastes.     

Process hazard assessment of energetic ionic liquid with kinetic evaluation and thermal equilibrium

With the continuous development of battery technology, there are new research investments in materials of various parts. In the field of electrolytes, ionic liquids (IL) are considered to be excellent electrolytes and have been widely studied in distinct energy fields. However, it is necessary to pay attention to the safety characteristics of ionic liquids at high temperature due to the application of energy, but there is little research on the reaction and kinetics of ionic liquids. To ensure the safety of ionic liquids, such as high temperature, the common ionic liquid 1-Ethyl-3-methylimidazolium nitrate ([Emim] NO₃) was selected for analysis. The exothermic mode is obtained from the data of differential scanning calorimetry. The basic reaction parameters of [Emim] NO₃ were determined with thermodynamic equation simulation. For ionic liquids in the actual situation, consider adding a heat balance model to estimate its temperature change pattern and find out the hazard temperature and related safety parameters. Temperature changes were estimated by constructing 25.0 g and 50.0 g packages to simulate material reactions and heat transfer in the external environment. The results showed that [Emim] NO₃ had shorter TMR_ad and TCL (<1 day) when the temperature was above 180 °C.     

一种基于分形结构的复合左右手传输线及其在小型化功分器中应用

首先提出了一种基于互补开口单环谐振器对（CSSRRP）的新型谐振式复合左右手传输线（CRLH TL）和其等效电路模型.采用Bloch理论对等效电路进行了深入研究,推导了CRLH TL工作于平衡态的计算公式.通过等效电磁参数提取,证明了该结构的负折射率与后向波传输特性.其次在CSSRRP中引入Koch分形结构,设计了工作于WiMAX波段的电小平衡零相移传输线.最后基于设计的零相移传输线制作了一分四串联功分器.对其进行测试,测试结果与仿真结果完全符合,从而验证了设计方法的正确性.与传统统蜿蜒线状一分四功分器相比,本文提出的功分器带宽有效展宽56%且尺寸缩减了42%.基于分形CSSRRP的左手传输线必将在小型化无线通信系统中得到广泛应用.     

水污染预警溯源技术应用案例研究

以南方某工业园区为例,研究了水污染预警溯源技术在园区企业污水排放精准监管中的应用。该技术提出污染源“水质指纹”概念,即每种污染源都有其唯一对应的水质指纹,以此进行污染排放源的识别。利用该技术监管企业排污,能准确监测到水质异常并发出预警,快速定位到嫌疑排污企业,从而可从源头解决污染问题,有效提升水环境监管工作效率。利用水质指纹识别技术,不仅可以识别企业超标排放和暗管偷排,而且可以进行污染路径溯源。案例研究表明,这项技术在水污染监管中发挥了重要作用。