汽车气制动ABS调节阀测试系统气动测试回路设计研究

针对气制动防抱死制动系统(ABS)调节阀测试系统气动回路设计进行研究;根据我国的汽车生产和检测现状,在确定气动测试回路总体方案的基础上,进行主控部分、负载回路、控制回路的设计和计算,所设计的气路检测系统可用于测试8种典型的气制动元件的密封性及动静态特性,通过不同的组合能够满足每一种阀的测试需求。该气动测试回路有效解决了简单阀类测量方法的不足,满足不了生产率及测量精度要求的问题。     

环境监测站人事制度改革的实践与思考

介绍了镇江市环境监测中心站人事制度改革的主要内容、做法及取得的成效。指出人事制度改革尤其是全额拨款事业单位的人事制度改革是政策性很强、涉及每个职工切身利益及触动诸多方面关系的一项复杂工程 ,为保证这项工程的顺利进行 ,应广泛宣传发动 ,统一思想认识 ,上下反复酝酿 ,制定工作方案 ,预见敏感问题 ,提出解决预案 ,主动沟通 ,争取上级支持 ,精心安排 ,快速稳妥实施 ,狠抓落实 ,深化改革成果。     

Distribution, sources, and potential risk of polycyclic aromatic hydrocarbons (PAHs) in drinking water resources from Henan Province in middle of China

Distribution and risk assessment of polycyclic aromatic hydrocarbons (PAHs) in drinking water resources have been carried out for the first time in Henan Province, China. Water samples collected from four river systems and their tributaries, as well as groundwater resources, were analyzed according to EPA method 525.2. Total of 68 water samples were collected in 18 cities in Henan province in May, August and November, 2001. Concentrations of sum of 16 priority PAHs in water samples ranged from 15 to 844 ng/L with a mean value of 178 +/- 210 ng/L (n = 68). The spatial and temporal distribution of PAHs showed that the Huanghe and the Huaihe river systems had relatively higher concentrations of total PAHs. Higher concentrations of total PAHs were observed in August and November than in May, with respective mean values of 262, 232 and 33.6 ng/L. Ratios of Ant/(Ant + Phe) and Flur/(Flur + Pyr) were calculated to evaluate the possible sources of PAH contamination, which indicated that the coal combustion sources were the main contributors to PAHs in most drinking water resources. Some petrogenic (or pyrolytic) sources of PAHs were also found. The toxic equivalency factors (TEFs) were used to calculate benzo[a]pyrene equivalents (BaPE) for water samples. The average value of BaPE was 0.6 ng/L. The values in most stations were much lower than the guideline values in drinking water of Chinese Environmental Protection Agency (CEPA, 2.8 ng/L) and the US Environmental Protection Agency (US EPA, 200 ng/L). Overall, the drinking water resources in Henan province showed some carcinogenic potential.     

Sources and seasonal variation of PAHs in the sediments of drinking water reservoirs in Hong Kong and the Dongjiang River (China)

The main objective of this study was to investigate occurrence of polycyclic aromatic hydrocarbons (PAHs) in the sources of the drinking water supply of Hong Kong. The main emphasis was on the Dongjiang River in mainland China which is the major source, supplying 80% of the total consumption in Hong Kong (the remaining 20% is obtained from rain water). Sediments were collected from four sites along the Dongjiang River and four reservoirs in Hong Kong during both the dry and wet weather seasons. The concentrations of total PAHs in the sediments ranged between 36 and 539 microg/kg dry wt. The lower levels were detected at the upstream site on the Dongjiang River and at the reservoirs in Hong Kong (44-85 microg/kg dry wt), while the mid- and downstream sites on the Dongjiang River were more polluted (588-658 microg/kg dry wt). Examination of the PAH profiles revealed that the mid- and downstream sections of the Dongjiang River contained high percentages of 4,5,6-ring PAHs, similar to the amounts of atmospheric particulate matter and road dust collected during the dry weather season from the Pearl River Delta region as reported in the literature. Seasonal changes were revealed in the reservoirs of Hong Kong, with higher PAH levels in the wet weather season than in the dry weather season. For those reservoirs in Hong Kong that store water from the Dongjiang River, a distinct seasonal pattern was also observed, namely, that under dry weather season conditions the PAHs found in the sediments were primarily from petrogenic source, while under wet weather season conditions they were from pyrolytic sources. No such pattern was detected in the reservoirs which stored only rain water.     

Multi-scale spatial structure of heavy metals in agricultural soils in Beijing

To effectively investigate the spatial variability of heavy metals in soil, produce a higher quality spatial distribution map, and identify the potential pollution sources of heavy metals, geostatistics was employed to evaluate the effect of scale on spatial variability of heavy metals in Beijing agricultural soils. The results revealed that spatial variability of Cr, Ni, Zn, and Hg was dependent on scale. Validation of the optimality of theoretical semivariance and comparative analysis of the estimation accuracy demonstrated that the multi-scale nested model can reveal the spatial structure of heavy metals effectively and improve the estimation accuracy better than the single-scale method, thereby enabling production a higher quality spatial interpolation map. Thus, the multi-scale kriging nested model is a useful tool for revealing spatial variability of heavy metals in soils, while the spatial distribution maps allow the identification of hot spots with high concentrations of heavy metals.     

Effects of potassium alkalis and sodium alkalis on the dechlorination of o-chlorophenol in supercritical water

Effects of potassium alkalis and sodium alkalis on the dechlorination of o-chlorophenol (o-CP) in supercritical water (SCW) were studied in this paper under the conditions of 450 degrees C and 25 MPa. Experimental results indicated that the dechlorination of o-CP can be accelerated significantly by all alkalis investigated. The dechlorination of o-CP proceeded mainly via two pathways: hydrodechlorination and hydrolysis. Both of the two pathways can be promoted by alkalis, and the dechlorination of o-CP can be accelerated by both the cations and hydroxide ion dissociated from alkalis. The overall dechlorination of o-CP can be accelerated by cations via promoting the hydrodechlorination pathway, while, hydroxide ion via promoting the hydrolysis pathway. In addition, the hydrodechlorination can be accelerated faster by sodium alkalis than that by potassium ones, while, the hydrolysis can be promoted faster by potassium alkalis. This difference may be caused by the different charge density between potassium ion and sodium ion, and the different solubility and dissociation constant between potassium alkalis and sodium alkalis in SCW. Dechlorination of o-CP with addition of alkalis prior to supercritical water oxidation (SCWO) process not only can avoid the reactor corrosion caused by the generated hydrochloric acid in direct SCWO of o-CP, but also can reduce the formation of toxic chlorinated byproducts compared with direct SCWO process or SCWO of o-CP with addition of alkali.     

考虑人为因素的可靠性评估

统计数据表明,系统的可靠运行不可忽略人为误操作造成的故障,该故障发生率有时甚至超过设备本身导致的系统故障发生率。将人为因素与设备自身因素造成的系统故障进行对比,分析人为因素造成系统故障后的特点,可得出人为因素的可靠性参数。根据解析法和模拟法的相关理论计算考虑人为因素的可靠性指标,可以看出考虑人为因素的计算结果更加符合实际运行特点,便于相关人员采取对策,保障系统的安全运行。     

从安全经济学看道路交通事故频发原因

针对我国目前道路交通事故频繁发生的现象,文章指出了事故发生的原因,并重点从安全经济学的角度,分析了事故发生的深层原因。然后运用安全经济学和安全科学的基本理论,提出了防止道路交通事故频发的合理、有效的对策。     

用海泡石处理采油废水

用海泡石吸附法处理采油废水,考察了处理时间、海泡石加入量和采油废水pH对采油废水COD去除率的影响,并通过正交实验优化了采油废水处理工艺条件。通过正交实验得到的采油废水处理最佳工艺条件为：处理时间6h,粒径为150μm的海泡石加入量200g／L,采油废水pH9。在该条件下处理采油废水,COD去除率达到91％,处理后出水的COD为34．71mg／L,小于GB8978-1996（（污水综合排放标准》中的一级标准（60mg／L）。