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261.
Hans Lazarus 《International journal of occupational safety and ergonomics》2013,19(3):233-250
Recognition of acoustic signals when perception is subject to interference from noise has already been extensively studied. In this study the influence of hearing protectors (HP) (plugs, muffs) and hearing loss on signal recognition is examined. Different spectrums and levels of the noise are also included. The test results are shown as the masked threshold for the signals heard and identified. In the case of normally hearing subjects a frequency-independent HP (plug) improves hearing performance, while frequency-dependent HP (muffs) tends to worsen it, especially with low-frequency noise. Hearing losses even worsen hearing performance when plugs are worn. Design suggestions are made to optimise signal recognition. Minimum signal-to-noise ratio and the use of HP are discussed. 相似文献
262.
Wenxiu Zhang Anthony K. Lau Zhiping S. Wen 《Journal of environmental science and health. Part. B》2013,48(5):496-505
Better understanding of the effects of key operational parameters or environmental factors on odor emission is of critical importance for minimizing the generation of composting odors. A series of laboratory experiments was conducted to examine the effects of various operating conditions on odor emissions. The results revealed that airflow rates that were too high or too low could result in higher total odor emissions. An optimal flowrate for odor control would be approximately 0.6 L/min.kg dry matter with intermittent aeration and a duty cycle of 33%. Temperature setpoint at 60°C appeared to be a turning point for odor emission. Below this point, odor emissions increased with increasing temperature setpoint; conversely, odor emissions decreased with increasing temperature setpoint above this point. With regard to the composting material properties, odor emissions were greatly affected by the initial moisture content of feedstock. Both peak odor concentration and emission rate generally increased with higher initial moisture content. Odor emission was significant only at moisture levels higher than 65%. An initial moisture level below 45% is not recommended due to concern with the resulting lower degree of biodegradation. Biodegradable volatile solids content (BVS) of feedstock had pronounced effect on odor emissions. Peak odor concentration and emission rate increased dramatically as BVS increased from 45% to 65%, thus, total odor emission increased exponentially with BVS. 相似文献
263.
介绍了粪尿分集生态卫生旱厕的特点及应用效果,该厕能节约和保护水资源,排泄物可再次利用,能形成可持续的完整的生态系统。具有较好的发展前景。 相似文献
264.
本文介绍生物脱臭的应用及其原理;并以自采的泥炭为载体,以硫化氢氧为试验气体,进行原始泥炭以及经过各种处理后泥炭臭性能的对比试验,由试验证明泥 一种比较理想的脱臭生物载体。 相似文献
265.
长江中下游地区旱涝急转的阈值诊断及危险性评估 总被引:2,自引:0,他引:2
选择与长江中下游地区夏季旱涝异常有关的15项大气环流指数作为自变量,以旱涝急转指数为因变量,采用非线性非参数的分类与回归树方法(CART)预测旱涝急转成灾的危险性等级。CART不仅能够提取出主要致灾因子,同时可以诊断不同影响阈值条件下,旱涝异常的类型及危险性等级。研究结果显示,夏季和春季北极涛动指数、春季亚洲径向环流指数,以及春季亚洲区极涡面积指数4项指标是旱涝突变成灾的主要影响因子,对旱涝急转成灾的危险程度具有很好的表征作用。当夏季北极涛动指数大于1.11时,更容易发生涝转旱事件(危险性等级为1级),而当夏季北极涛动指数小于或等于1.11,同时春季北极涛动指数大于或等于-1.11时,更容易发生旱转涝事件(危险性等级为6级),其他危险性等级的条件也可从模型中直接判读出来。采用2011~2013年的实测数据和模型预测结果进行对比,两者非常接近,验证了模型的可靠性。采用的CART方法为长江中下游地区旱涝急转致灾的等级预测提供了一种新的思路。 相似文献
266.
为研究天津市中心城区北塘排污河恶臭污染特征,沿北塘排污河布设5个采样点位,分别在夏、秋、冬三季进行了系统采样.北塘排污河夏、秋、冬三季总检出浓度为23.842 5 mg/m^3,夏季(9.273 1mg/m^3)>冬季(8.388 4 mg/m^3)>秋季(6.181 0 mg/m^3),靖江桥和兵营桥两个点位受赵沽里泵站出水水质的影响较大,对周围的恶臭污染程度更为严重.北塘排污河污染物质总检出浓度组成特征:无机气体>含氧烃>烷烃>芳香烃>卤代烃>烯烃>硫化物,共检出物质67种,检出率大于70%的污染物共30种,广泛存在的物质为11种,主要恶臭污染物为少量的含氧烃、无机气体和硫化物,乙醛、丙酮、硫化氢和甲硫醇为北塘排污河主要恶臭污染物. 相似文献
267.
Oxidation of inorganic contaminants by ferrates (VI, V, and IV)--kinetics and mechanisms: a review 总被引:1,自引:0,他引:1
Sharma VK 《Journal of environmental management》2011,92(4):1051-1073
Inorganic contaminants are found in water, wastewaters, and industrial effluents and their oxidation using iron based oxidants is of great interest because such oxidants possess multi-functional properties and are environmentally benign. This review makes a critical assessment of the kinetics and mechanisms of oxidation reactions by ferrates (Fe(VI)O(4)(2-), Fe(V)O(4)(3-), and Fe(IV)). The rate constants (k, M(-1) s(-1)) for a series of inorganic compounds by ferrates are correlated with thermodynamic oxidation potentials. Correlations agree with the mechanisms of oxidation involving both one-electron and two-electron transfer processes to yield intermediates and products of the reactions. Case studies are presented which demonstrate that inorganic contaminants can be degraded in seconds to minutes by ferrate(VI) with the formation of non-toxic products. 相似文献
268.
结合国内公共建筑火灾中影响人员生命安全的因素,提出一种公共建筑火灾中人员生命风险分析的方法。该方法根据人员生命危险出现的临界时间和疏散公式,可以定量计算出人员的伤亡率,以公共建筑火灾中可能的人员伤亡率大小评价公共建筑火灾中人员生命风险大小,进而分析出公共建筑火灾中可能影响人员伤亡的主要因素,最后提出减少人员伤亡的对策。结果表明该方法可以快速地估算出公共建筑物发生火灾的伤亡,并分析提出减少人员伤亡的方法。 相似文献
269.
270.