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991.
高层建筑电梯活塞效应及烟气控制分析 总被引:3,自引:1,他引:2
在电梯运行活塞效应及其对火灾烟气影响理论分析基础上,分析电梯井和前室加压及压力波动情况;结合高层建筑烟控系统的原理,通过合理的压差设计,可保证电梯系统在最大容许压差和最小容许压差之间正常工作。通过对活塞效应及其对电梯与建筑空间之间压差影响的分析发现,极限状态下烟气可能卷入电梯井和前室,对人员的疏散造成威胁,提出了控制活塞效应影响的上限临界压差。研究表明,合理的排气泄压系统、气压式挡烟系统、可变送风系统及火灾层带通风排烟设施的系统等均能对火灾烟气进行有效控制,提高电梯疏散的安全性。研究所得的结论为火灾中利用电梯进行疏散提供了理论指导及一种烟气控制的方法。 相似文献
992.
E. Le Cadre F. Gérard S. Génermont T. Morvan S. Recous 《Environmental Modeling and Assessment》2009,14(4):539-544
We compared three formalisms derived from (1) medical sciences, (2) environmental, and (3) agronomic models to simulate the
effects of pH and temperature on the nitrification rate in arable soils. We evaluated these formalisms by implementing them
in a simple growth model by comparing modelled and measured nitrate contents of soil samples with different initial soil pH
after incubation at two temperatures. We found that the formalisms derived from medical sciences were more accurate and easily
adapted to the data, suggesting that such formalisms may be profitably used in agronomic or environmental models. 相似文献
993.
Natura 2000, the nature network based on the European Bird and Habitat Directives, is explicitly grounded on ecological science. To acquire a permit under the Dutch Nature Conservation Act, an appropriate assessment of significant effects must be conducted based on the best available scientific knowledge. In this way the scientific and policy world are directly linked. This article focuses on ‘significant effect’ as a boundary object to analyse how science–policy interactions shape the meaning and assessment of significant effect and how these interpretations influence the decision-making process. To this end, two conflicts over significant effect are investigated: the conflict over the 2006-spring permit for the mussel seed fishery, and the 2011 permit for the planned World Championship powerboat races. In both cases nature organisations started a court process against the government-granted permits in protest to the “no significant effect” claim, stating that there was insufficient certainty for this conclusion. These conflicts are approached as controversies between discourse coalitions with different interpretations of the ecological knowledge. We show how significant effect became a focal point in the controversies, limiting the debate to ecological arguments and science-based expertise, but also creating options for parties to advance their protest by articulating uncertainties. Only uncertainty of incomplete knowledge was explicitly addressed, excluding ambiguity of values and unpredictability of the actual ecosystem. We suggest that acknowledging the value aspect in disputes on significant effect would leave more space for effective solutions of the problems under debate. 相似文献
994.
995.
996.
Situating Hazard Vulnerability: People’s Negotiations with Wildfire Environments in the U.S. Southwest 总被引:1,自引:1,他引:0
This article is based on a multimethod study designed to clarify influences on wildfire hazard vulnerability in Arizona’s
White Mountains, USA. Findings reveal that multiple factors operating across scales generate socially unequal wildfire risks.
At the household scale, conflicting environmental values, reliance on fire insurance and firefighting institutions, a lack
of place dependency, and social vulnerability (e.g., a lack of financial, physical, and/or legal capacity to reduce risks)
were found to be important influences on wildfire risk. At the regional-scale, the shift from a resource extraction to environmental
amenity-based economy has transformed ecological communities, produced unequal social distributions of risks and resources,
and shaped people’s social and environmental interactions in everyday life. While working-class locals are more socially vulnerable
than amenity migrants to wildfire hazards, they have also been more active in attempting to reduce risks in the aftermath
of the disastrous 2002 Rodeo-Chediski fire. Social tensions between locals and amenity migrants temporarily dissolved immediately
following the disaster, only to be exacerbated by the heightened perception of risk and the differential commitment to hazard
mitigation displayed by these groups over a 2-year study period. Findings suggest that to enhance wildfire safety, environmental
managers should acknowledge the environmental benefits associated with hazardous landscapes, the incentives created by risk
management programs, and the specific constraints to action for relevant social groups in changing human-environmental context. 相似文献
997.
水仙对多效唑比较敏感,无论浸泡法或叶面喷施法都具有明显的矮化效应,但当浓度≥200mg·l-1时又会产生药害,也有碍观赏;叶面喷施法对水仙矮化效应不如浸泡法,开花期亦迟10·15d;浸泡法的最佳处理浓度是50 mg·l-1;叶面喷施法以浓100-200mg·l-1效应最好,但此法费工费时,操作不便,生产上最好不采用。 相似文献
998.
覆盖旱作水稻的生物效应及吸氮特征 总被引:3,自引:0,他引:3
研究了田间条件下旱作水稻半腐解秸秆覆盖、蚕豆秆覆盖、地膜覆盖、纸膜覆盖、生稻草覆盖 5种覆盖方式的吸氮特征 ;水稻水作与旱作的产量及其构成因素 ;水稻水作与旱作条件下灌溉水的利用效率。结果表明 ,旱作条件下水稻各部位的含氮量均大于水作 ;旱作水稻的氮素吸收、累积主要在拔节期以后 ,而水作水稻从移栽后就大量吸收氮素 ,灌浆期后很少吸收氮素 ;旱作水稻的产量以半腐解覆盖处理的最高 ,为 8415kg/hm2 ;旱作水稻耗水量只占水作耗水量的 7 14% ,旱作水稻的水分利用效率是水作的 12倍以上 相似文献
999.
S.H.L. Yim J.C.H. Fung A.K.H. Lau S.C. Kot 《Atmospheric environment (Oxford, England : 1994)》2009,43(32):4982-4994
The objective of this study is to investigate the air ventilation impacts of the so called “wall effect” caused by the alignment of high-rise buildings in complex building clusters. The research method employs the numerical algorithm of computational fluid dynamics (CFD – FLUENT) to simulate the steady-state wind field in a typical Hong Kong urban setting and investigate pollutant dispersion inside the street canyon utilizing a pollutant transport model. The model settings of validation study were accomplished by comparing the simulation wind field around a single building block to wind tunnel data. The results revealed that our model simulation is fairly close to the wind tunnel measurements. In this paper, a typical dense building distribution in Hong Kong with 2 incident wind directions (0° and 22.5°) is studied. Two performance indicators are used to quantify the air ventilation impacts, namely the velocity ratio (VR) and the retention time (Tr) of pollutants at the street level. The results indicated that the velocity ratio at 2 m above ground was reduced 40% and retention time of pollutants increased 80% inside the street canyon when high-rise buildings with 4 times height of the street canyon were aligned as a “wall” upstream. While this reduction of air ventilation was anticipated, the magnitude is significant and this result clearly has important implications for building and urban planning. 相似文献
1000.
I. Zvonova P. Krajewski M. Ammann V. Filistovic B. Kanyar S.L. Simon D. Webbe-Wood 《Journal of environmental radioactivity》2010,101(1):8-10003
Within the project “Environmental Modelling for Radiation Safety” (EMRAS) organized by the IAEA in 2003 experimental data of 131I measurements following the Chernobyl accident in the Plavsk district of Tula region, Russia were used to validate the calculations of some radioecological transfer models. Nine models participated in the inter-comparison. Levels of 137Cs soil contamination in all the settlements and 131I/137Cs isotopic ratios in the depositions in some locations were used as the main input information. 370 measurements of 131I content in thyroid of townspeople and villagers, and 90 measurements of 131I concentration in milk were used for validation of the model predictions.A remarkable improvement in models performance comparing with previous inter-comparison exercise was demonstrated. Predictions of the various models were within a factor of three relative to the observations, discrepancies between the estimates of average doses to thyroid produced by most participant not exceeded a factor of ten. 相似文献