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81.
82.
借助遥感数据和GIS空间分析技术,选取生物多样性维持、土壤保持、水源涵养和固碳4种生态系统服务建立评估模型,对2000—2010年重庆市域内3个重要生态功能区——三峡库区水源涵养重要区(下称三峡重要区)、秦巴山区水源涵养重要区(下称秦巴重要区)和都市区“四山”生态屏障重要区(下称“四山”重要区)生态系统服务的时空变异特征进行综合研究. 结果表明:①2000—2010年,三峡重要区4种生态系统服务均呈增强趋势. ②秦巴重要区内,生物多样性维持和水源涵养功能总体较好,并且持续增强;固碳功能有所减弱,该时段内固碳功能高等级面积减少了931.90 km2. ③“四山”重要区土壤保持和水源涵养功能有所增强,生物多样性维持和固碳功能略有减弱. ④重庆市重要生态功能区生态系统服务以中和较高等级分布为主,空间差异较大,异质性明显. 生态系统服务较好区域主要分布在渝东北秦巴山区以及中西部植被覆盖较好的山脊;市域中部长寿、垫江、涪陵等区县生态系统服务相对较弱. 10 a间,重庆市重要生态功能区生态系统服务总体呈变好趋势,但局部地区有所减弱,主要表现为秦巴和“四山”重要区固碳功能的降低. 相似文献
83.
84.
《Process Safety and Environmental Protection》2014,92(1):3-16
This paper discusses the validation of discharge and subsequent atmospheric dispersion for both unpressurised and pressurised carbon dioxide releases using the consequence modelling package Phast.The paper first summarises the validation of the Phast dispersion model (UDM) for unpressurised releases. This includes heavy gas dispersion from either a ground-level line source (McQuaid wind-tunnel experiments) or an area source (Kit-Fox field experiments). For the McQuaid experiments minor modifications of the UDM were made to support line sources. For the Kit Fox experiments steady-state and 20-s finite-duration releases were simulated for both neutral and stable conditions. Most accurate predictions of the concentrations for finite duration releases were obtained using the UDM Finite Duration Correction method.Using experiments funded by BP and Shell and made available via DNV's CO2PIPETRANS JIP, the paper secondly summarises the validation of the Phast discharge and dispersion models for pressurised CO2 releases. This modelling accounted for the possible presence of the solid CO2 phase following expansion to atmospheric pressure. These experiments included both high-pressure steady-state and time-varying cold releases (liquid storage) and high-pressure time-varying supercritical hot releases. Both the flow rate and the concentrations were found to be predicted accurately.The above validation was carried out with no fitting whatsoever of the Phast extended discharge and dispersion models. 相似文献
85.
The consequence modelling package Phast examines the progress of a potential incident from the initial release to the far-field dispersion including the modelling of rainout and subsequent vaporisation. The original Phast discharge and dispersion models allow the released substance to occur only in the vapour and liquid phases. The latest versions of Phast include extended models which also allow for the occurrence of fluid to solid transition for carbon dioxide (CO2) releases.As part of two projects funded by BP and Shell (made publicly available via CO2PIPETRANS JIP), experimental work on CO2 releases was carried out at the Spadeadam site (UK) by GL Noble Denton. These experiments included both high-pressure steady-state and time-varying cold releases (liquid storage) and high-pressure time-varying supercritical hot releases (vapour storage). The CO2 was stored in a vessel with attached pipework. At the end of the pipework a nozzle was attached, where the nozzle diameter was varied.This paper discusses the validation of Phast against the above experiments. The flow rate was predicted accurately by the Phast discharge models (within 10%; considered within the accuracy at which the BP experimental data were measured), and the concentrations were found to be predicted accurately (well within a factor of two) by the Phast dispersion model (UDM). This validation was carried out with no fitting whatsoever of the Phast extended discharge and dispersion models. 相似文献
86.
The aim of this paper is to provide an investigation, using large eddy simulation, into plume dispersion behind an aircraft
in co-flowing take-off conditions. Validation studies of the computational model were presented by Aloysius and Wrobel (Environ
Model Softw 24:929–937, 2009) and a study of the flow and dispersion properties of a double-engine aircraft jet was presented
by Aloysius et al. (EEC/SEE/2007/001, EUROCONTROL Experimental Centre, ), in which only the engine was modelled. In this paper, the complete geometry of a Boeing 737 is modelled and investigated.
The current work represents a contribution towards a better understanding of the source dynamics behind an airplane jet engine
during the take-off and landing phases. The information provided from these simulations will be useful for future improvements
of existing dispersion models. 相似文献
87.
88.
包头市大气氟化物总量控制排放许可证研究 总被引:1,自引:0,他引:1
总结了包头市实施大气排污许可证制度试点中,关于氟化物总量控制许可值的确定方法,主要包括源强的确定、大气扩散模式筛选与验证、总量控制区划定与执行标准、控制点选择、污染源贡献率和削减量计算、许可值的优化分配。 相似文献
89.
趋势面方法在大气污染物观测与分析中的应用 总被引:2,自引:1,他引:1
提出了大气污染物观测是与分析中的一种新的方法——趋势面方法。这种用多项式函数模拟的趋势面可以找出城市大气降尘的总的趋势变化,还可以找出受局部因素影响具有局部特点的变化。 相似文献
90.
An outbreak of scurvy in Somali refugee camps* 总被引:1,自引:0,他引:1
Between June and October 1982, an outbreak of scurvy occurred in the refugee camps of Somalia. An epidemiologic investigation eventually detected more than 2,000 cases. The outbreak came at a time when the relief programme had been well established and the general health status of the refugees had otherwise stabilized. We report on 72 of the cases. Joint pain of the lower extremities and gingivitis were prominent features in the majority. Hemorrhagic phenomena were not observed and no deaths occurred. The outbreak primarily affected the poorer refugees who were unable to purchase locally available Vitamin C-containing foods. This outbreak demonstrates the vulnerability of a large population of displaced persons who are dependent on imported relief supplies for survival. 相似文献