节能减排调控模型的系统仿真与目标优化

基于略阳县灾后恢复重建与振兴全县经济的需要和国家、陕西省有关节能减排战略部署的实情,对略阳经济发展现状和环境质量进行分析后,认为采取一定的调控措施,可实现协调灾后恢复重建地区经济与完成地区节能减排的目标。研究首先构建适合略阳县的节能减排系统动力学调控模型,通过选取产业结构调节系数和环保投资比重的不同组合,设定4种情景方案进行仿真,并对仿真结果进行目标优化,比选出较为适合的节能减排调控策略。研究认为,描述变量之间关系的方程和关键参数的确定对于系统动力学建模的质量至关重要,设定不同情景对模型进行仿真和目标优化可为定量决策和科学调控提供技术支撑。研究结果表明：在近期（2010~2012年）,采取激励主导工业发展与较高环保投入相结合的策略更有利于灾后略阳经济尽快恢复和发展,同时兼顾节能减排任务的完成;在中期（2013~2016年）和远期（2017~2020年）,采取主导工业平稳发展与较高环保投入相结合的策略更有利于全县按照循环经济发展模式,实现可持续健康协调发展。同时,研究结果还给出了备选方案和规避方案作为决策参考。     

Spatial distribution of dissolved Pb, Hg, Cd, Cu and As in the Bohai Sea

Characteristics of the spatial distribution of selected dissolved heavy metals were analyzed during large scale surveys from August 12 to 25,2003 in the Bohai Sea.Dissolved Pb was the only element with average concentrations higher than the grade-one sea water quality standard of China.The spatial distribution of dissolved Pb in surface water was similar to those of Cd,Cu and As,where the isopleths generally indicated decreasing values from the bays to the central areas.Only for Hg did the high concentrations not only appear in Liaodong Bay,Bohai Bay and Laizhou Bay,but also in the Central Area,viz.not only in inshore but also in offshore areas. Vertical distributions of dissolved Pb,Cd,Cu and As were largely uniform,while that of dissolved Hg increased with depth.We infer that the input of pollutants from land was the main influencing factor for the detected distribution patterns of dissolved heavy metals, followed by the dynamics of sea water,release from bottom sediments and biochemical processes.Comparing with historical data, average concentrations of dissolved heavy metals appear to decline in recent years.     

中国可持续发展问题的系统动力学研究进展

可持续发展问题是当前的一个研究热点。鉴于可持续发展问题的综合性、系统性和复杂性。系统动力学是这一研究的有效工具。本文简要回顾了我国学者近年来应用系统动力学研究可持续发展问题的部分工作，提出了在这一领域进一步研究的若干方向。     

重庆市温室气体排放系统动力学研究

在全球气候变暖和快速城市化的背景下,开展城市温室气体减排研究十分迫切。重庆作为中国五大中心城市之一和西部唯一的直辖市,其协调经济发展和节能减排的实现模式对广大西部地区具有重要示范意义。本研究从社会经济发展的内部结构出发,以经济和人口增长导致的能源消费为核心,构建重庆市温室气体排放的系统动力学模型。研究中考虑不同投资率下的高、中、低三种经济发展模式,并在此基础上设置节能和低碳情景,探求节能水平提高、能源结构改善和碳汇能力增强对未来重庆温室气体排放的影响。模拟结果表明,产业能耗水平降低即节能情景,是重庆市温室气体减排的主要途径,对保证2020年中国单位GDP二氧化碳排放比2005年下降40%-45%目标的实现具有一定借鉴意义。最后本文在产业结构、能源消费、碳汇增加等方面针对重庆未来低碳经济发展提出对策建议。     

Production disruption management for R/M integrated supply chain using system dynamics methodology

The impacts of production disruption in Remanufacturing/Manufacturing (R/M) integrated supply chain on the sales and the methods of production disruption management were studied. A system dynamics model for the R/M integrated supply chain with production disruption was improved by system dynamics methodology. The numerical examples were shown to illustrate the simulation results. The impacts of different recovery times of production disruption on the sales were presented. In order to mitigate the disruption risks and ensure the sales at the needed sales ratio, the methods for setting multi-echelon inventory levels before the occurring of the production disruption and the methods for making back-up plans after the production disruption occurs were given.     

城市地震次生灾害演化机理分析及仿真研究

根据对城市地震次生灾害发生机理的分析,绘制了地震次生灾害演化的因果回路图和存量流量图。在此基础上借助系统动力学仿真软件Vensim PLE,对城市地震次生灾害演化过程建立了系统动力学模型,并进行了模型验证及仿真,得出了不同防震抗灾能力下城市地震次生灾害可能造成的损失情况,为城市防震救灾工作提供参考。     

基于系统动力学和灵敏度模型的生态校园物流分析

在生态校园的研究中,尝试性地采用了把系统动力学模型和灵敏度模型相结合的方法对生态校园物流分析进行研究,通过系统动力学模型分析生态校园内部各要素之间的相互关系并绘制了系统框图;在此基础上运用局部灵敏度模型分析校园系统每个要素的变化,对校园系统影响的灵敏度程度和模拟校园的发展趋势,找出对校园系统影响较大的关键性要素,为生态校园建设和规划提供了重要的参考资料,对优化校园系统的物流起到了指导作用。     

Spatiotemporal variation of radon and carbon dioxide concentrations in an underground quarry: coupled processes of natural ventilation, barometric pumping and internal mixing

Radon-222 and carbon dioxide concentrations have been measured during several years at several points in the atmosphere of an underground limestone quarry located at a depth of 18 m in Vincennes, near Paris, France. Both concentrations showed a seasonal cycle. Radon concentration varied from 1200 to 2000 Bq m⁻³ in summer to about 800-1400 Bq m⁻³ in winter, indicating winter ventilation rates varying from 0.6 to 2.5 × 10⁻⁶ s⁻¹. Carbon dioxide concentration varied from 0.9 to 1.0% in summer, to about 0.1-0.3% in winter. Radon concentration can be corrected for natural ventilation using temperature measurements. The obtained model also accounts for the measured seasonal variation of carbon dioxide. After correction, radon concentrations still exhibit significant temporal variation, mostly associated with the variation of atmospheric pressure, with coupling coefficients varying from −7 to −26 Bq m⁻³ hPa⁻¹. This variation can be accounted for using a barometric pumping model, coupled with natural ventilation in winter, and including internal mixing as well. After correction, radon concentrations exhibit residual temporal variation, poorly correlated between different points, with standard deviations varying from 3 to 6%. This study shows that temporal variation of radon concentrations in underground cavities can be understood to a satisfactory level of detail using non-linear and time-dependent modelling. It is important to understand the temporal variation of radon concentrations and the limitations in their modelling to monitor the properties of natural or artificial underground settings, and to be able to assess the existence of new processes, for example associated with the preparatory phases of volcanic eruptions or earthquakes.     

Atmospheric radon in Hong Kong

For the first time in Hong Kong, atmospheric radon concentration was continuously monitored between November 2007 and October 2008. This paper presents the results obtained during the 12-month period. The annual mean atmospheric radon concentration in Hong Kong was found to be 9.3 Bq m⁻³ which was close to the level at neighbouring places like Guangdong and Taiwan. An estimation of the dose arising from atmospheric radon to the Hong Kong population was made. The meteorological effects on the variation of atmospheric radon concentration were discussed. It was found that the origin of the airmass and stability of the local atmosphere played vital roles in the seasonal and diurnal variations respectively, whereas precipitation caused abrupt changes in rainy days. An attempt was also made to find out the contribution of atmospheric radon to the ambient gamma dose rate.     

Computational fluid dynamics simulations of hydrogen releases and vented deflagrations in large enclosures

This paper presents model predictions obtained with the CFD tool FLACS for hydrogen releases and vented deflagrations in containers and larger enclosures. The paper consists of two parts. The first part compares experimental results and model predictions for two test cases: experiments performed by Gexcon in 20-foot ISO containers (volume 33 m³) as part of the HySEA project and experiments conducted by SRI International and Sandia National Laboratories in a scaled warehouse geometry (volume 45.4 m³). The second part explores the use of the model system validated in the first part to accidental releases of hydrogen from forklift trucks inside a full-scale warehouse geometry (32 400 m³). The results demonstrate the importance of using realistic and reasonably accurate geometry models of the systems under consideration when performing CFD-based risk assessment studies. The discussion highlights the significant inherent uncertainty associated with quantitative risk assessments for vented hydrogen deflagrations in complex geometries. The suggestions for further work include a pragmatic approach for developing empirical correlations for pressure loads from vented hydrogen deflagrations in industrial warehouses with hydrogen-powered forklift trucks.