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211.
针对电梯“掉层”故障,通过现场勘查和模拟试验等方法,对电梯“掉层”现象的原因进了分析,提出了相应的处理和预防措施。 相似文献
212.
阿勒泰地区面积约 1 1 .7× 1 0 4 km2 ,拥有广阔的森林和充沛的水资源。有 1个国家级和 3个自治区级自然保护区 ,在保护区内栖息着众多的国家一、二类保护动物和珍禽异兽 ,有较丰富的生物多样性 ,属生态环境大区。做好该地区的生态环境保护的管理工作十分重要 ,通过多年的实际工作经验及心得 ,谈了作者对阿勒泰地区生态环境保护工作的思路 相似文献
213.
Xuemei WANG Weihua CHEN Duohong CHEN Zhiyong WU Qi Fan 《Frontiers of Environmental Science & Engineering》2016,10(1):53-62
Understanding the trends in PM2.5 levels is essential for formulating clean air plans. This paper analyzes PM2.5 data from various published sources for the years 2000 to 2010 in the Pearl River Delta Economic Zone (PRDEZ). The long-term variation in PM2.5 mass concentration is analyzed. Results show that PM2.5, organic carbon (OC), elemental carbon (EC), and S O 4 2 − show a similar trend, increasing before 2005 and then decreasing slightly. The annual average PM2.5 concentration ranges from 49.1 μg·m−3 in 2000 to 64.3 μg·m−3 in 2010, with a peak of 84.1 μg·m−3 in 2004. None of these 11 years meets the new National Ambient Air Quality standard (NAAQS) for PM2.5 (35 μg·m−3). Overall average concentrations of OC, EC, and S O 4 2 − are 13.0, 6.5, and 11.8 μg·m−3, respectively. N O 3 − and N H 4 + respectively have concentrations of 1.5 μg·m−3 and 2.9 μg·m−3 in 2000 and 6.4 μg·m−3 and 5.3 μg·m−3 in 2010, with a statistically significant average annual trend of+ 0.2 μg·m−3·yr−1 and+ 0.1 μg·m−3·yr−1. In certain geographic regions, OC and EC contribute most of the PM2.5, while in other regions secondary water-soluble ions are more important. In general, OC and S O 4 2 − are the dominant components of PM2.5, contributing 20.6% and 18.6%, respectively. These results provide, for the first time, a better understanding of the long-term PM2.5 characteristics and trends, on a species-by-species basis, in the PRDEZ. The results indicate that PM2.5 abatement needs to prioritize secondary species. 相似文献
214.
215.
Concentrations of the natural radionuclides 238U, 226Ra, 232Th and 40K have been measured by γ-ray spectrometry in 796 topsoil samples from the Pearl River Delta Zone (PRDZ) of Guangdong, China. The mean concentrations for 238U, 226Ra, 232Th and 40K were found to be 140 ± 37 Bq kg−1, 134 ± 41 Bq kg−1, 187 ± 80 Bq kg−1 and 680 ± 203 Bq kg−1 dry mass, respectively. These values were all higher than the mean values in soil for China and the world. Outdoor air-absorbed dose rates, calculated from activity concentrations of 226Ra, 232Th and 40K, ranged from 86 to 237 nGy h−1, with a mean value of 165 ± 46 nGy h−1. The corresponding annual outdoor effective dose rate per person was estimated to be between 0.11 and 0.29 mSv y−1, with a mean value of 0.20 ± 0.06 mSv y−1, which was also higher than the world mean value of 0.07 mSv y−1. The radium equivalent activity (Raeq) and the external hazard index (Ir) resulted from the natural radionuclides in soil, were also calculated and found to vary from 230 to 676 Bq kg−1 and from 0.6 to 1.8, respectively. The Raeq and the Ir in all the investigated regions were up to 75% higher than the set limits of 370 Bq kg−1 and 1.0, respectively. 相似文献
216.
芜湖经济技术开发区土地集约利用评价研究 总被引:1,自引:0,他引:1
通过界定开发区土地集约利用内涵,构建评价指标体系,运用特尔斐法、多因素综合评价法,选择评价模型并确定权重,对芜湖经济技术开发区进行土地集约利用评价。结果表明,开发区土地集约利用度综合分值较高,但区内综合容积率偏低,投资产出比有待提高。提出以规划、产业结构调整等促进土地集约利用的政策措施,并对评价指标体系和思路进行了讨论。 相似文献
217.
Fire is the most prevalent accident in natural gas facilities. In order to assess the risk of fire in a gas processing plant, a fault tree analysis (FTA) and event tree analysis (ETA) has been developed in this paper. By utilizing FTA and ETA, the paths leading to an outcome event would be visually demonstrated. The framework was applied to a case study of processing plant in South Pars gas complex. All major underlying causes of fire accident in a gas processing facility determined through a process hazard analysis (PHA). Fuzzy logic has been employed to derive likelihood of basic events in FTA from uncertain opinion of experts. The outcome events in event tree has been simulated by computer model to evaluate their severity. In the proposed methodology the calculated risk has the unit of cost per year which allows the decision makers to discern the benefit of their investment in safety measures and risk mitigation. 相似文献
218.
起重机供电电源断错相保护功能的常规检验方法较为烦琐,有时还可能影响检验结果的正确判断.设计一种供电电源断错相自动切换装置用于断错相保护功能的检验,以降低劳动强度、提高检验效率,并有效保证检验结论的正确性. 相似文献
219.
由地震活动参数分析郯城—庐江断裂带中南段现今活动习性及强震、中强震危险性 总被引:1,自引:0,他引:1
张恩立 《防灾减灾工程学报》2008,28(2)
根据近38年的地震资料,利用地震活动参数值组合、b值空间分布、断裂带分段,结合历史地震及构造背景的综合分析方法,分析了郯城—庐江断裂带中南段现今地震活动习性,判别出潜在的强震、中强震危险段落。研究结果表明:郯城—庐江断裂带中南段存在着6个具有不同现今活动习性的分段落,其中,郯城—泗洪段断层面的现今活动习性处于高应力背景下的相对闭锁状态,是未来最有可能发生强震的段落;九江段于2005年发生了5.7级地震,积累多年的能量已经释放,闭锁状态已被打开,现处于震后震源断层面应力调整阶段,出现了低b值、高应力的状态,因此,短期内不可能再复发中强以上地震;潍坊—莒县段、定远段、合肥—庐江段、宿松段的现今活动则处于低应力水平状态,较短时期内复发中强以上地震的可能性较小。 相似文献
220.