农电网改造中应注意的问题

结合农电网改造工作实践及特点,阐述了过去农电网中出现的问题,提出了在改造过程中应注意的问题及对策措施.     

Characteristics and anthropogenic sources of carbonyl sulfide in Beijing

Atmosphericmixing ratios of carbonyl sulfide (COS) in Beijingwere intensivelymeasured from March 2011 to June 2013. COS mixing ratios exhibited distinct seasonal variation, with a maximumaverage value of 849 ± 477 pptv in winter and a minimal value of 372 ± 115 pptv in summer. The seasonal variation of COS was mainly ascribed to the combined effects of vegetation uptake and anthropogenic emissions. Two types of significant linear correlations (R² > 0.66) were found between COS and CO during the periods from May to June and from October to March, with slopes (ΔCOS/ΔCO) of 0.72 and 0.14 pptv/ppbv, respectively. Based on the emission ratios of COS/CO from various sources, the dominant anthropogenic sources of COS in Beijing were found to be vehicle tire wear in summer and coal burning in winter. The total anthropogenic emission of COS in Beijing was roughly estimated as 0.53 ± 0.02 Gg/year based on the local CO emission inventory and the ΔCOS/ΔCO ratios.     

高峰矿提升机用钢丝绳无损检测方法的研究

介绍了利用漏磁场原理检测钢丝绳断丝 ,磁桥回路测量钢丝绳磨损信号 ,并实现在一个传感器中对上述多种缺陷的综合检测。在信号处理方面 ,结合不同信号特征 ,设计了相应的电路和处理软件 ,实现了缺陷的定量检测     

电线电缆行业漆包线生产工艺废气中有机物的GC/MS测定

本文以活性炭、ＴｅｎａｘＧＣ、聚氨酯泡沫为吸附材料,用二硫化碳洗脱、二氯甲烷提取、加热解吸三种脱附方式,并以色谱／质谱（ＧＣ／ＭＳ）联用仪为测试手段,对漆包线生产工艺废气中的有机物进行了测定,共检出７２种有机化合物。本文进行了不同采集方式间的比较,提出了电线电缆行业工艺废气中有机化合物的系统分析方法。     

中国电线积冰灾害危险性评估和区划

中国有关电线积冰方面的观测资料太少,难以直接用于灾害评估。为了解决这个问题,利用1960-2009年现有的电线积冰和常规气象资料,在分析观测冰重和常规气象指标相关性的基础上,逐步筛选出影响冰重的主要气象指标,构建了电线积冰灾害危险性评估的常规气象指标体系,再利用常规气象资料采用多元线性回归方法估算积冰量,对中国电线积冰灾害危险性进行了评估和区划。结果表明:(1)在综合考虑相关性和空间代表性的基础上,影响雨凇和混合凇冰重的主要气象指标为过程平均风速、积冰时间、过程累计降水量;影响雾凇的为过程平均风速、过程浓雾时间。(2)中国大部分地区电线积冰灾害危险性较低,中高危险区面积较小,分布特征表现出明显的南北差异。中高危险区呈带状分布于南方地区的长江中下游山地丘陵区,北方地区则呈点状分布,具体位置与山地丘陵、江河湖泊均有着密切的关系。     

天维膜处置钢丝绳酸性废液实验中存在的问题

南通地区很多钢丝绳企业采用酸洗磷化工艺,产生大量含铅、铁、锌等重金属离子的酸性废液,造成区域特征性环境污染.选用山东天维膜技术有限公司的扩散渗析阴膜进行钢丝绳酸性废液处置实验.结果表明:该膜能有效地将酸、盐分离,酸的回收率达到90％以上,铅截留率达到70％以上,铁截留率达到80％以上.但实验中出现氯化铅晶体析出,堵塞处...     

浅谈钢丝绳的安全使用

介绍了钢丝绳的基本结构,提出了钢丝绳的选用原则,对钢丝绳的安全使用提出了指导性的建议。     

Numerical simulation and experimental study on metallographic structure characteristics of melting trace caused by overcurrent fault of copper wire

The microscopic characteristics of melting trace caused by copper wire fault are an important basis for the physical evidence identification of electrical fires. Metallography is an important method in electrical fire research, and computer-aided quantitative analysis on metallographic structure is common in materials aspect. In this study, the metallographic structure and phase composition characteristics of melting trace caused by overcurrent fault were explored with the aid of a metallographic microscope and an X-ray diffractometer (XRD). The results show that the grains are mainly slender dendritic and columnar crystals when the current is 128 A, while they are coarse dendritic and cellular crystals when the current is greater than 192 A; the average grain diameter of melting trace of copper wire grows with the increase in current. The main phases of melting trace caused by overcurrent fault of copper wire are α-Cu base and Cu₂O, and the new phases Cu₄Si and Cu₂Mg are formed when the current is higher than 160 A. In addition, the solidification process of metallographic structure of copper wire under different currents was simulated by the Procast software. It is found that the simulation results are basically in agreement with the experimental data, which suggests that this model can effectively predict the microstructure characteristics of melting trace of copper wire under different currents. The research results can provide a sound basis for the physical evidence identification of electrical fire and improve the accuracy and scientificity of electrical fire investigation.     

Parametric study along with selection of optimal solutions in dry wire cut machining of cemented tungsten carbide (WC-Co)

This work deals with parametric study of dry wire EDM (WEDM) process of cemented tungsten carbide. Experiments have been conducted using air as dielectric medium to investigate effects of pulse on time, pulse off time, gap set voltage, discharge current and wire tension on cutting velocity (CV) surface roughness (SR) and oversize (OS). Firstly, a series of exploratory experiments were carried out to identify appropriate gas and its pressure. Afterward, preliminary experiments were conducted to investigate effects of process parameters on dry WEDM characteristics and find appropriate ranges for each factor. Then a central composite rotatable method was employed to design experiments based on response surface methodology (RSM). Empirical models were developed to create relationships between process factors and responses by considering to analysis of variances (ANOVA). To increase the predictability of the process, intelligent models have been developed based on back-propagation neural network (BPNN) and accuracy of these models was compared with mathematical models based on root mean square error (RMSE) and prediction error percent (PEP). In order to select optimal solutions in the cases of single-objective and multi-objectives optimization problems, optimization includes two main approaches. First approach was based on mathematical model and desirability function. Also second approach was designed based on neural network and particle swarm optimization. These approaches were applied in both cases of single-objective and multi-objectives optimization problems and their results were compared with together. Results indicated that selection of air at inlet pressure of 1.5 bar is really appropriate for conducting experiments of next stages. Also, the BPNN creates more accurate prediction rather than mathematical model. Moreover, the BPNN-PSO approach was more efficient in optimization of process rather than mathematical model-desirability function in respect with validation tests.     

时效对高导耐热铝合金导线第二相析出及其性能的影响

目的 开展时效过程中61.5%IACS高导耐热铝合金导线析出第二相特性及其电导率与拉伸力学性能变化规律的研究,评价其热稳定性。方法 经过150~230 ℃长达630 h时效,揭示第二相的组成、形态与分布及其对时效态铝合金导线电导率与拉伸力学性能的影响规律。结果 时效态铝合金导线中,颗粒状及针状A13Zr(Y, Er)、A13(Zr(Y)xErl?x)第二相在Al晶内、晶界析出,A13Fe相颗粒弥散分布于Al晶界。伴随着时效过程,铝合金导线的抗拉强度与伸长率先上升、再逐渐下降;同时,铝合金导线的电导率先增大、后逐渐趋于稳定。该趋势随时效温度的升高而越加明显。结论 第二相的析出、长大是影响时效态铝合金导线力学性能及电导率的主要原因。经230 ℃、1 h时效,铝合金导线的强度保持率高达94%,满足GB/T 30551—2014的要求。所有时效态铝合金导线的电导率均高于其初始值,该高导耐热铝合金导线的热稳定性良好。