喀斯特石山地区社会经济与生态环境可持续发展系统研究:以桂西北为例

本建立了广西西北部喀斯特石山地区可持续发展的系统动力学模型。并用DYNAMO程序预测了未来20年桂西北地区的人口、工业、农业、第三产业，生态环境，土地资源，社会总产值，人均国民收人等的动态变化趋势，结果显示，该地区由于人口，工业资产增加使物质和能源消耗增长太快，而对污染治理的投入又太少，导致桂西北地区的生存环境质量下降，因此应当加大对污染治理的投入力度，改善区域环境质量，这是实现息烽县区域可持续发展的关键，根据区域特点探讨了桂西北喀斯特贫困山区的形成演化，提出了可持续发展的途径。     

Landscapes and environments on the island of Ouessant,Brittany, France: From traditional maintenance to the management of abandoned areas

For about 50 years the desertion of areas by traditional activities has led to an important evolution of landscapes and environments on the island of Ouessant. The study of this evolution has been undertaken at different spatial and temporal scales. On one part of the island, a scientific investigation carried out at the scale of the parcel enabled the form of the landscape in 1850 to be compared with that of 1985. On the whole island, the evolution of spatial organization and land use was compared between 1950 and 1985. For each of three main ecological environments, vegetational successions after the decrease of agriculture have been studied along with their future potential changes. This work highlights some considerations about the present management of the environment in relation to the major objectives of island environmental policies.     

大气中SO2的液相氧化研究

大气中ＳＯ２液相氧化是形成酸雨的重要途径，降雨中含有各种无机离子和有机物质，它们可能催化或抑制液相氧化反应的进行。本文根据四川酸雨样品组成，进行了ＳＯ２在模拟雨水及实际雨水中的氧化实验，考查了Ｖ，Ｆｅ，Ｍｎ等离子对ＳＯ２氧化的催化作用，Ｈ２Ｏ２对ＳＯ２的氧化以及降水中有机物质甲醛对各反应的影响。实验结果为了解酸雨的成固，研究酸雨控制对策提供了科学依据。     

Impacts of interannual climate variability on past and future forest composition

Numerous analyses of the possible impacts of future climatic changes on tree species composition have been published for both lowland and high-elevation forests. Most of these studies were based on the application of forest "gap" models, and the vast majority of them considered only changes in the average of climatic parameters over time. In this study, we use a unique data set on reconstructed past climatic variations to analyse forest dynamics simulated by the forest gap model ForClim. This analysis forms the basis for a systematic exploration of the ecological effects of changing means vs. changing variability of climate on central European forests. A reconstruction of historical climate covering the last 470 years in the Swiss lowlands (ClimIndex) is extrapolated to a transect across the alpine (cold) treeline and used to simulate the influence of climate variations on the time scale of decades on forest biomass and tree species composition at both sites. While the simulation at the low-elevation site shows little sensitivity to climate variations, the results from upper subalpine forests suggest that two major dieback events would have occurred at elevations above the current but below the climatic tree line, induced by clusters of exceptionally cold summers. The results are in agreement with available dendrochronological data and with documentary evidence on massive negative impacts on flora and fauna at high elevations during these periods. We conclude that ForClim is capable of capturing the effects on tree population dynamics of climate variability at these sites as reconstructed from the ClimIndex record. A factorial design is used to address the sensitivity of ForClim to changes of the long-term averages vs. changes of the variability of monthly temperature and precipitation data. To this end, the simulated tree species composition of near-natural forests is examined along a climate gradient in Europe. The results indicate that there are three types of forest response: (1) little sensitivity to both kinds of change, (2) strong sensitivity to changes in the means, but little sensitivity to changing variability, and (3) strong sensitivity to changing variability at least in parts of the examined climate space. Half of the cases investigated fall under the third category, suggesting that emphasis should be placed on also assessing the sensitivity of ecosystems to future changes in climate variability rather than on changes of average values alone. Electronic Publication     

城市海岸带环境管理模式优化研究——以青岛市胶州湾为例

我国的海洋污染日益严重,政府加大海洋环境保护力度势在必行。科学、有效的海洋环境管理对保护环境、提高资源利用效率起着非常重要的作用。但海洋环境并不是一维线性的系统,涉及系统的多维耦合,而海岸带又是与人类活动息息相关的重要部分。本文尝试以青岛市胶州湾海岸带环境管理模式为例,构建包含有"经济-人口-资源-环境-安全-行政(EPRESA)"六个子系统的多维耦合系统模型,并绘制出总流图,然后以此为管理模式的优化提供前提性分析,提出海岸带综合管理模式优化的对策建议。本研究认为,要改善现有的海岸带环境管理体系,应该制定综合性管理政策,建立可持续的融资机制,推进海岸带灾害与风险管理以及引导利益相关者参与管理。     

Blast wave clearing behavior for positive and negative phases

The purpose of the research was to improve prediction of response of buildings to blast waves by including the negative phase and considering clearing of both positive and negative phases. Commonly used structural design practices, which trace their origins to military design manuals, often ignore the negative phase as well as positive phase clearing. For high explosive threats, this approach is conservative in most circumstances. However, negative phase clearing had not previously been studied for blast waves, and the implications for structural response had not been evaluated. This paper presents results of modeling negative phase blast clearing behavior for a typical blast wave and discusses the differences from positive phase clearing. The implications of including positive and negative phase clearing in building blast damage analysis are also investigated through single-degree-of-freedom (SDOF) analyses.Blast waves from explosion sources like a vapor cloud explosion (VCE), pressure vessel burst or high explosive exhibit both positive and negative phases, and the relative magnitude of the positive and negative phases varies among explosion sources and the specific circumstances of each source. A fully reflected blast wave is produced if an incident blast wave were to strike an infinitely tall and wide wall in a normal orientation. Both the positive and negative phases of the blast wave are enhanced by the reflection process. However, when an incident blast wave strikes a wall of finite size in a normal orientation, rarefaction waves are created at the edges of the wall, and the rarefactions sweep down from the roof and inward from sides. The rarefaction waves result in a clearing effect for both the positive and negative phases.Clearing relieves some of the applied blast load on the reflected wall for the positive phase. However, this is not always the case for the negative phase. As shown by the results presented in this paper, clearing may either relieve or enhance the applied negative phase blast load, depending on the duration of the blast wave and the wall dimensions.The impact of negative phase clearing on structural response for generic building components was also investigated. Nonlinear SDOF methods were used to characterize response in terms of peak positive and negative displacements. It was found that the influence of the negative phase is significant and the peak structural response can occur during negative (outward) displacement.     

高速公路安全水平仿真分析

为深入研究高速公路安全系统,用系统动力学(SD)方法分析驾驶员、车辆、道路、应急救援等组成要素以及环境、管理等影响因素之间的关系,建立高速公路安全系统因果关系模型和存量流量模型。用层次分析法(AHP)确定各影响因素的权重。以三福高速公路为例,用Vensim软件模拟高速公路运营期间系统安全的变化情况。结果表明,在该高速公路运营期间,系统安全与车辆安全度呈先上升后下降的趋势、道路安全度呈下降趋势、驾驶员安全度与应急救援能力呈上升趋势。通过与实际数据对比,验证了模型的有效性。     

Application of CFD on the sensitivity analyses of some parameters of the modified Hartmann tube

The aim of this work is to determine the influence of operating parameters such as the dispersion pressure, the ignition delay and height on the dust flammability. A Computational Fluid Dynamics (CFD) simulation, based on an Euler–Lagrange approach, was developed with Ansys Fluent™ and validated experimentally. Such analysis will facilitate the choice of the most conservative conditions for a flammability test. This paper is focused on a case study performed on wheat starch with the modified Hartmann tube. The dispersion process of the powder was studied with granulometric analyses performed in situ and high speed videos. Tests were performed with injections at gas pressure ranging from 3 to 6 bars and the evolution of the particle size distribution (PSD) was recorded at different ignition heights (5, 10 and 15 cm over the dispersion nozzle). The observations highlighted the presence of agglomeration/deagglomeration processes and dust segregation. Besides, a CFD simulation analysis was aimed at evaluating the impact of a set of parameters on the PSD and the local turbulence, which are closely linked to some flammability parameters. For this computational analysis, the CFD simulation was coupled with a collision treatment based on a Discrete Element Method (DEM) in order to consider the cohesive behavior of the combustible dust. Thus the results suggest performing the injection of the gases at approximately 5 bars for the flammability tests of wheat starch in order to obtain the finest PSD at a given ignition height. It is also shown that the finest PSD are obtained at 5 cm over the dispersion nozzle. However, the local instabilities and turbulence levels are so high during the first stages of the dispersion that the flame growth can be disturbed for short ignition delays. Moreover, the stabilization of the bulk of the dust cloud requires longer periods of time when the ignition sources are located at 15 cm. As a result, the recommended height to perform a flammability test is 10 cm in this case. Finally, this study proposes some tools that might improve the procedure of dust flammability testing.     

Environmental policy and macroeconomic dynamics in a new Keynesian model

This paper studies the dynamic behavior of an economy under different environmental policy regimes in a New Keynesian model with nominal and real uncertainty. We find the following results: (i) an emissions cap policy is likely to dampen macroeconomic fluctuations; (ii) staggered price adjustment alters significantly the performance of the environmental policy regime put in place; (iii) the optimal environmental policy response to shocks is strongly influenced by the degree to which prices adjust and by the monetary policy reaction.