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841.
目的为提升隔振装置的隔振性能,研发具有优良隔振性能的隔振装置。方法在20~1600 Hz频段内,利用有限元分析软件对某新型复合隔振器隔振装置进行谐响应分析,并进行整体隔振试验,得出隔振装置在外激励下频域上的振动响应。结果对比分析有限元仿真结果与隔振试验数据,在20~80 Hz内,振级落差大于15 dB,在200~1600 Hz上,振级落差也在24 dB以上,在200~1000 Hz上加速度振级落差仿真和实验的RMS值分别为36.6 dB和38.9 dB,结论该复合式隔振器隔振装置具有优良的隔振性能。 相似文献
842.
不同氮水平下间作对玉米土壤硝化势和氨氧化微生物数量的影响 总被引:9,自引:1,他引:8
利用荧光定量PCR(real-time quantitative PCR,Q-PCR)技术,结合氨氧化细菌(ammonia oxidizing bacteria,AOB)和氨氧化古菌(ammonia oxidizing archaea,AOA)丰度和土壤理化性质的测定,探索了不同氮水平下间作对玉米土壤硝化势(PNF)的影响.试验设置玉米单作和与马铃薯间作两个种植模式,4个施氮水平(不施氮N0、1/2常规施氮N1、常规施氮N2和3/2常规施氮N3)的随机区组试验.结果表明,从不施氮到常规施氮,土壤硝化势和AOA、AOB数量均随施氮量增加而逐渐增加,而高氮(N3)时与N2没有显著差异;间作对土壤硝化势、AOA与AOB数量的影响与施氮量和作物生育期有关,低氮投入(N1)间作有利于增加土壤氨氧化微生物数量和硝化作用.施肥是硝化势增加的主要驱动因子,相关性分析结果表明,土壤含水量是影响PNF的主要环境因子;PNF与土壤中AOA、AOB amoA基因丰度成显著的正相关.尽管玉米马铃薯间作降低了土壤中AOA、AOB amoA基因丰度,却使得间作土壤中AOB占据氨氧化微生物数量上的优势.以上结果表明,施氮和间作均影响了土壤硝化作用和氨氧化微生物AOA和AOB数量的变化,这些变化会影响土壤环境质量. 相似文献
843.
贵阳市污水处理厂中典型抗生素的污染水平及生态风险 总被引:5,自引:4,他引:1
为了解贵阳市污水处理厂对进水中典型抗生素的去除情况及污水处理厂出水对受纳水体中水生生物的影响,对贵阳市两座污水处理厂进出水及受纳水体中9种典型抗生素进行调查.结果表明,污水处理厂进出水中抗生素均有不同程度检出,进出水中抗生素的浓度范围在ND~835. 60 ng·L~(-1)和ND~286. 60 ng·L~(-1)之间,其中氧氟沙星(OFX)浓度最高,进水分别为835. 60 ng·L~(-1)和539. 00 ng·L~(-1),出水分别为11. 74 ng·L~(-1)和286. 60 ng·L~(-1).污水处理厂对抗生素的去除率为-42. 29%~100%,其中四环素(TC)被完全去除.进出水中抗生素的浓度与国内外其它地区污水处理厂相比处于较低水平.通过对受纳水体中抗生素的检测分析发现,受纳水体中OFX的浓度最高,污水处理厂出水是受纳水体中抗生素的来源之一.通过生态风险评估也发现OFX对受纳水体中水生生物存在高风险(RQ 1). 相似文献
844.
西湖景区土壤中邻苯二甲酸酯污染水平、来源分析和空间分布特征 总被引:4,自引:4,他引:0
为考察杭州西湖景区土壤环境中邻苯二甲酸酯(phthalate esters,PAEs)的污染情况,本研究采集了西湖景区4种不同土地利用类型土壤共42个土壤样品,利用气相色谱三重四级杆质谱联用仪(GC-MS/MS)对所有样品中6种PAEs的含量水平和组成情况进行了分析,并采用主成分分析法和普通克里金插值法对不同土地利用类型土壤中PAEs的来源与空间分布进行了详细探讨.结果表明,西湖景区6种邻苯二甲酸酯累计含量(ΣPAEs)范围为597. 6~7 360. 1μg·kg~(-1),邻苯二甲酸二甲酯(DMP)、邻苯二甲酸二正丁酯(DBP)和邻苯二甲酸二(2-乙基)己酯(DEHP)是3种主要的PAEs污染物,三者总含量平均值贡献率高达98. 43%,而DEHP作为含量最高的PAEs单体贡献率为66. 28%;不同土地利用类型土壤中的PAEs组成由于其来源不同而具有差异性,交通运输与游客活动是西湖景区内PAEs的主要来源; 6种PAEs主要分布在西湖景区的东北区域,呈现出由北向南、自东向西递减趋势. 相似文献
845.
Anders Jacobsson Åsa EkRoland Akselsson 《Journal of Loss Prevention in the Process Industries》2011,24(4):333-343
Learning from incidents is considered a very important source for learning and improving safety in the process industries. However, the effectiveness of learning from reported incidents can often be questioned. Therefore, there is a need to be able to evaluate the effectiveness of learning from incidents, and for that purpose we need methods and tools. In this paper, a method is described for evaluating the effectiveness of learning, based on the idea of “level of learning” of the lessons learned. The level of learning is expressed in terms of how broadly the lesson learned is applied geographically, how much organizational learning is involved and how long-lasting the effect of learning is. In the 6-step method, the incidents reported in a typical incident learning system are evaluated both for the actual and the potential level of learning in a semi-quantitative way with different tools. The method was applied in six process industries on a large number of incidents. The method was found to be very useful and to give insights of aspects that influence the learning from incidents. 相似文献
846.
张秋洁 《中国安全科学学报》2011,21(6)
为了解我国农民工参加工伤保险的影响因素,提高农民工工伤保险的参保率,通过对全国9个省市共3 848名农民工的问卷调查,应用Logistic回归模型分析政策的因素和企业的因素对农民工参加工伤保险的影响。结果表明,农民工是否参加工伤保险受到各地工伤保险政策以及农民工所在企业两方面的影响。从政策的角度看,个体工商户参加工伤保险的规定、工伤保险基金的统筹水平以及工伤保险的偿付方式对农民工参加工伤保险有显著影响;从企业的角度看,农民工所在企业是否建有工会、企业所有制对农民工参加工伤保险有显著影响。建议各地进一步明确工伤保险政策中对个体工商户的参保要求,继续提高工伤保险基金的统筹水平,增加农民工领取工伤保险偿付的方式。建议劳动保障部门加强对未建有工会的企业,加强对私企,特别是个体工商户的监察力度。 相似文献
847.
基层应急体系现状调查分析 总被引:1,自引:0,他引:1
通过发放调查问卷和实地走访的形式,对基层应急体系存在的问题做出详细的分析,发现其应急预案体系、人员队伍及公众的培训教育、应急物资储备及应急管理社会参与程度都存在很多的不足,并提出完善预案体系、组织管理体系和推进应急队伍建设、应急物资建设、公众的教育培训和强化防灾应急演练及防灾减灾活动等相应的具体措施,从而全方位稳步推进基层应急体系的建设。 相似文献
848.
以经济效益、资源产出力、资源环境承载力相协调为目标,在多层次评价指标体系下,引入产业结构综合评价坐标系统(CECS,comprehensive evaluating coordinate system),对基于资源环境承载力的产业结构进行定性和定量相结合的描述分析,在分析产业结构构成时综合运用统计学方法和威孚-托马斯逼... 相似文献
849.
Evaluating the effects of future climate change and elevated CO2 on the water use efficiency in terrestrial ecosystems of China 总被引:2,自引:0,他引:2
Qiuan Zhu Hong Jiang Changhui PengJinxun Liu Xiaohua WeiXiuqin Fang Shirong LiuGuomo Zhou Shuquan Yu 《Ecological modelling》2011,222(14):2414-2429
Water use efficiency (WUE) is an important variable used in climate change and hydrological studies in relation to how it links ecosystem carbon cycles and hydrological cycles together. However, obtaining reliable WUE results based on site-level flux data remains a great challenge when scaling up to larger regional zones. Biophysical, process-based ecosystem models are powerful tools to study WUE at large spatial and temporal scales. The Integrated BIosphere Simulator (IBIS) was used to evaluate the effects of climate change and elevated CO2 concentrations on ecosystem-level WUE (defined as the ratio of gross primary production (GPP) to evapotranspiration (ET)) in relation to terrestrial ecosystems in China for 2009-2099. Climate scenario data (IPCC SRES A2 and SRES B1) generated from the Third Generation Coupled Global Climate Model (CGCM3) was used in the simulations. Seven simulations were implemented according to the assemblage of different elevated CO2 concentrations scenarios and different climate change scenarios. Analysis suggests that (1) further elevated CO2 concentrations will significantly enhance the WUE over China by the end of the twenty-first century, especially in forest areas; (2) effects of climate change on WUE will vary for different geographical regions in China with negative effects occurring primarily in southern regions and positive effects occurring primarily in high latitude and altitude regions (Tibetan Plateau); (3) WUE will maintain the current levels for 2009-2099 under the constant climate scenario (i.e. using mean climate condition of 1951-2006 and CO2 concentrations of the 2008 level); and (4) WUE will decrease with the increase of water resource restriction (expressed as evaporation ratio) among different ecosystems. 相似文献
850.
Residual levels and health risk of polycyclic aromatic hydrocarbons in freshwater fishes from Lake Small Bai-Yang-Dian, Northern China 总被引:2,自引:0,他引:2
Fu-Liu Xu Wen-Jing WuJun-Jun Wang Ning QinYan Wang Qi-Shuang HeWei He Shu Tao 《Ecological modelling》2011,222(2):275-286
The residual levels of polycyclic aromatic hydrocarbons (PAHs) in the liver, brain, gill and muscle tissues of four common edible freshwater fish species including crucian carp, snakehead fish, grass carp and silver carp collected from Lake Small Bai-Yang-Dian in northern China were measured by GC-MS. The distribution and composition pattern of PAHs in the fish tissues, and the effects of lipid contents in fish tissues and the octanol-water partition coefficient (Kow) of PAHs congeners on them were analyzed. The human health risk of PAHs though fish consumptions was estimated. The following results were obtained: (1) The average residual levels of total PAHs (PAH16) on wet weight base in the different tissues of each fish species ranged from 4.764 to 144.254 ng/g ww. The differences in the average residual levels on wet weight base for PAH16 within four fish species were not statistically significant (P > 0.05); however, these within four fish tissues were statistically significant (P < 0.01). (2) There were very similar distribution patterns of PAH congeners among both the fish tissues and the fish species, as indicated by statistically significant positive interrelationships (R = 0.58-0.97, P < 0.01 or P < 0.05). Low molecular weight (LMW) PAHs predominated the distribution in the fish tissues, accounting for 89.97% of total PAHs. Phe was the most dominant component, according for 37.79% of total PAHs, followed by Ant (18.59%), Flo (12.59%), Nap (10.79%), Fla (9.82%) and Pyr (6.43%). (3) The PAHs residues and distribution in the fish tissues are dependent on both the Kow of PAH congeners and the lipid contents in the fish tissues. There was a significant positive relationship (R = 0.7116, P < 0.0001) between lipid contents and PAHs residual levels. The statistically significant negative relationships (P < 0.05) were found between LogKow and log-transformed PAHs contents on wet weight base for all fish tissues except for the muscle tissue of snakehead fish, the brain and liver tissues of crucian carp. (4) The risk levels of total PAHs were lower than 10−5 for the muscle tissues of four studied fish species and for the brain tissues of grass carp and snakehead fish; while these were higher than 10−5 for the brain tissues of crucian carp and silver carp. The risk levels of total PAHs in the liver tissues of four studied fish species except for snakehead fish exceeded 10−5 for 2-4.5 times. However, the potency equivalent concentration (PEC) of total PAHs in four studied fish tissues were still lower than the maximum permissible BaP limits for crops and baked meat and for plants in the national criterions. The distributions of PAH congeners in fish were well simulated by a level III fugacity model, especially for low molecule weight PAHs. 相似文献