钢管混凝土组合柱在标准火与真实火中的行为比较

以实际工程中常用的钢管混凝土组合柱为研究对象,通过ABAQU S大型有限元软件模拟钢管混凝土组合柱在标准火和真实火中的截面温度分布、应力、变形、破坏形态、耐火极限等力学行为。其中标准火选用ISO-834标准火模型,真实火采用欧洲规范Eurocode 1 Part 1-2中的参数火模型来近似模拟真实火灾的温度—时间关系。研究发现,钢管混凝土柱在两种火场环境中的行为差异很大,真实火中的冷却过程对钢管混凝土的破坏起重要的影响。基于本研究,还初步得到火灾过程中环境温度的升温速度、柱火灾荷载比等对钢管混凝土组合柱的抗火性能的影响。     

中国自然资源政策演进历程与发展方向

自然资源政策是国家政策体系的重要组成部分,其社会关注度、复杂性、地区差异性等特征较为突出.1980年代以来,中国自然资源政策大致经历了上世纪80年代、1991-1997、1998-2003、2004 - 2010等四个阶段的演进,期间,社会经济发展形势不断发展变化,自然资源政策的需求和目标也不断变化,并为社会经济快速发展提供了政策基础;但同时也在政策一致性、政策权威性、政策公正性、政策认知性等方面,暴露出一些不足和缺憾.自2011年开始,资源政策的演进进入了第五个阶段.展望未来,为全面落实科学发展观和加快转变经济发展方式,中国自然资源政策应不断创新,重点在政府规制、全面负责、促进转型、系统协调和差异设计等方面不断优化和发展.     

Integrated Approaches to Natural Resources Management in Practice: The Catalyzing Role of National Adaptation Programmes for Action

The relationship of forests in water quantity and quality has been debated during the past years. At the same time, focus on climate change has increased interest in ecosystem restoration as a means for adaptation. Climate change might become one of the key drivers pushing integrated approaches for natural resources management into practice. The National Adaptation Programme of Action (NAPA) is an initiative agreed under the UN Framework Convention on Climate Change. An analysis was done to find out how widely ecosystem restoration and integrated approaches have been incorporated into NAPA priority adaptation projects. The data show that that the NAPAs can be seen as potentially important channel for operationalizing various integrated concepts. Key challenge is to implement the NAPA projects. The amount needed to implement the NAPA projects aiming at ecosystem restoration using integrated approaches presents only 0.7% of the money pledged in Copenhagen for climate change adaptation.     

我国自然旅游资源产权制度的建构——兼谈对湘西州的启示

产权制度激励和约束着自然旅游资源治理中相关利益主体的行为,决定其管理和利用的绩效。当前我国自然旅游资源的应有功能与价值不能有效实现,主要源于自然旅游资源产权制度存在诸多缺陷。为构建完善的自然旅游资源产权制度,有必要选择合理的产权模式,健全产权交易制度和完善产权保障制度。     

A case for gender equity in governance of the Okavango Delta fisheries in Botswana

Fish is a major source of livelihood for the majority of people living around the Okavango Delta in northwestern Botswana. Gender dynamics and governance regimes determine differential access to, and control of, resources between women and men in the area. The purpose of this case study is to critically assess the embeddedness of gendered inequities in the governance of Okavango Delta fishery. Primary data was collected through focus group discussions and face‐to‐face interviews of 96 basket fishers from five villages along the Panhandle area of the Okavango River. The study found that past and present Okavango Delta fishery policy and programme interventions tended to entrench rather than minimize gendered disparities between women and men fishers' access to and control over fish resources, asset accumulation and employment opportunities. Basket fishers have intimate knowledge of flood variability, fish migration and habitat and use this knowledge to make decisions about when and where to harvest what fish species. Women fishers' ecological knowledge, interests and concerns however, have been excluded from current zoning and closed season regulations and co‐management structures. The paper concludes that past and current development interventions as well as the regulatory framework continue to entrench pre‐existing gender relations in the fishery sector which excludes, disempowers and marginalizes women fishers. We recommend innovative co‐management and local based structures which recognize the diversity of interests and interest groups.     

天然沸石颗粒对NH4^＋动态吸附过程中的离子交换特性研究

采用天然斜发沸石颗粒,进行了沸石吸附水溶液中NH4^＋的动态吸附实验研究。实验结果表明,沸石颗粒粒径、沸石床高度、上升流速、进水氨氮浓度、进水水质等因素对沸石颗粒吸附NH4^＋有着明显的影响,在工程实践应用时,要根据动态吸附实验结果选择合适的设计及运行参数。离子交换机理研究表明,Na^＋首先被交换出来,随着反应进行,Ca^2＋浓度逐渐增加,两者成为离子交换的主要对象。对于人工氨氮配水,整个运行期间金属阳离子液相增加量明显大于NH4^＋去除量,这与金属阳离子在固液两相间的再分配作用有关;对于厌氧工艺出水,在吸附初期,NH4^＋去除量大于金属阳离子液相增加量,随着反应进行,两者逐渐持平。     

天然沸石颗粒对NH4+动态吸附过程中的离子交换特性研究

采用天然斜发沸石颗粒,进行了沸石吸附水溶液中NH4+的动态吸附实验研究.实验结果表明,沸石颗粒粒径、沸石床高度、上升流速、进水氨氮浓度、进水水质等因素对沸石颗粒吸附NH4+有着明显的影响,在工程实践应用时,要根据动态吸附实验结果选择合适的设计及运行参数.离子交换机理研究表明,Na+首先被交换出来,随着反应进行,Ca2+...     

How much more exposed are the poor to natural disasters? Global and regional measurement

This paper proposes a simple indicator to measure the exposure to natural disasters for the poor and non-poor population, in order to assess the global and regional trend of natural hazard and poverty. Globally, poor people are two times more exposed to natural disasters than the non-poor in the twenty-first century. The time trend varies across regions, with poor people in East Asia and Pacific being most exposed to natural disasters, followed by those in South Asia and Sub-Saharan Africa. The change of exposure measure over time is decomposed into two factors: a pure exposure change, which could be fuelled by climate change; and a concentration component. The result shows that the total net increase of exposure between the 1970s and the 2000s is driven significantly by the increased concentration of the poor (26 per cent) in disaster-prone areas, whereas the contribution of that factor remains very small for the non-poor (six per cent).     

再论自然灾害风险的定义

系统地总结了现有自然灾害风险的定义,并指出其存在的问题。重新甄别了自然灾害系统的组成要素及其作用机制,深入分析了自然灾害风险的核心内涵,据此提出了自然灾害风险的新定义,即自然灾害风险是由自然灾害系统自身演化而导致未来损失的不确定性。结合定义的相关规则,对自然灾害风险新定义进行了符合性验证。新定义不仅深化了人们对自然灾害风险本身的认识,而且明确了自然灾害风险评估的内容。     

Effects of wavelength and water quality on photodegradation of N-Nitrosodimethylamine (NDMA)

N-Nitrosodimethylamine (NDMA) is a potent carcinogen that yields a cancer risk of 10⁻⁶ at concentrations as low as 0.7 ng L⁻¹. Tentative guideline values are set at 3 ng L⁻¹ in California, USA; 9 ng L⁻¹ in Ontario, Canada; 40 ng L⁻¹ nationwide in Canada; and 100 ng L⁻¹ by the World Health Organization. NDMA is a great concern in treating reclaimed water as well as drinking water. UV degradation can be considered effective degradation method. A 1-log reduction of NDMA is achieved by 1000 mJ cm⁻² of a 254-nm low pressure (LP) mercury UV lamp. However, a higher degradation efficiency than that provided by LP lamps is desired in practical treatment. In this study, the effects of wavelength and water quality were investigated to achieve higher degradation efficiency. The effects of wavelength were examined by comparing three UV lamps: a 222-nm Kr Cl Excimer UV lamp, a 254-nm LP mercury UV lamp, and a 230- to 270-nm filtered medium pressure (FMP) mercury UV lamp. The 222-nm lamp and FMP lamp achieved 4 times and 2.8 times higher degradation efficiency, respectively, than the conventional 254-nm LP lamp. Effects on water quality were also simulated by using absorption spectrum data of nitrate solutions and process water from a drinking-water treatment plant. In the simulation, the 222-nm lamp was affected by UV-absorbing compounds in the water, whereas the FMP lamp showed more stable degradation efficiency. Appropriate use of these three types of lamps could enhance the efficiency of degradation of NDMA.