人口与经济发展对植被的影响研究

植被是陆地表面主要的覆盖物，也是许多地球系统过程的重要变量。人类活动对植被的影响在区域尺度上是显著的。以重庆市为例，使用滑动平均和SG滤波对SPOT/VGT NDVI时间序列数据进行了平滑处理，结合GDP和人口栅格化数据，从时间序列和空间相关场两个方面分析了植被与人类活动因子之间的时空相关性。结果表明，从1998到2005年，植被的分布和生长状况并没有随GDP和人口的持续增加而增加。在时间序列上，植被覆盖与GDP和人口之间总体上呈显著的负相关关系；在空间上，这种相关关系表现出了较强的异质性。空间相关场表明：较强的负相关主要发生在相对发达的主城区周围，反映了快速的经济发展和城市化使得植被面积和生产力降低；然而在偏远的山区，由于经济落后同时植被覆盖较少，出现了正相关。     

滨海城市环境工程地质问题成灾特点分析

滨海城市是我国经济最发达的地区，近年来经济与城市建设均得到迅速发展，城市土地开发力度加大，由此起起的环境工程地质问题也日趋严重。本文分析了我国滨海城市环境工程地质问题的主要类型，研究了环境工程地质问题的成灾特点。     

北美自由贸易区和欧盟的环境政策：趋向,启示与对策

以北美自由贸易区和欧盟为代表的区域性经济集团已在经济利益与环境保护挂钩的制度性安排方面取得诸多进展，它们不同程度地在机构设置、协定条款、资金安排等方面强化了环境要求，并在国际环境公约的执行上表现出积极、灵活的特点。这一切都将为未来多边经济体系中环境问题的协商和解决开辟了新的途径， 也为我国在实施可持续发展过程中的环境制度化建设提供可鉴之处。     

Solution-oriented global environmental assessments: Opportunities and challenges

This article provides an introduction to the Special Issue dedicated to “Solution-oriented Global Environmental Assessments: Opportunities and Challenges”. In the follow-up to the Paris climate agreement and the adoption and early implementation of the global Sustainable Development Goals involving many synergies and trade-offs, the need to shift the focus from environmental problem analysis towards the exploration of specific solution options can be observed in international environmental governance debates. To remain policy-relevant, credible and legitimate, global environmental assessments (GEAs) must carefully adapt to a rapidly evolving governance landscape. This Special Issue sheds light on the potential utility and implications of increased solution-orientation of GEAs. It builds on the research project “The Future of Global Environmental Assessment Making” that was jointly initiated in 2013 by UN Environment and the Mercator Research Institute on Global Commons and Climate Change. The article collection includes research on the coevolution of GEAs and the increasingly solution-oriented governance context; conditions of success for contemporary GEAs; the treatment of divergent viewpoints, stakes and stakeholders in solution-oriented GEAs; knowledge aggregation; and the enhanced measurement of GEA effectiveness in the emerging governance landscape.     

A “measurable” definition of sustainable development based on closed cycles of resources and its application to energy systems

Human society consumes resources that it is not able to reproduce. Human activities are still based on “open cycles,” starting from a condition of natural environmental balance and reaching an environmental imbalance. The challenging scope of scientific and technological research towards sustainability appears clear if it is based on this analysis: to find development systems based on “closed cycles” of resources. The challenging objective of realizing closed cycles leads to a definition of sustainability that indicates the path to sustainable development, as well as stating the general principle. It also provides a key to the qualitative measurement of sustainability. This means that the sustainability level of a system can be measured by measuring its capacity to avoid the consumption of resources. Zero consumption is a necessary condition for sustainability, and brings about as a side effect the highly desired “zero-waste” result. Materials entering the proposed endless scheme pass through the process of usefulness without losing their capacity to feed the system again after being used. Thus, the concept of “consumption” itself is replaced by one of “use” when resources are inserted into closed loops capable of feeding human development. The application of the closed cycle sustainability criterion particularly displays its feasibility, and a theoretical guiding role, in the energy sector. Energy vectors such as hydrogen and electricity enable the closure of the energy resources loop by effectively approaching the objective of “zero consumption” (and the side result of “zero waste”) through already demonstrated technological solutions.     

室内空气环境质量的探讨

介绍了室内空气环境质量的国内外有关研究成果。内容包括IAQ问题引发关注的缘由,IAQ的影响因素、评价方法及改善IAQ的相关措施。     

Reducing the risk level for pipelines transporting carbon dioxide and hydrogen by means of optimal safety valves spacing

In many countries where electricity generation is based on their natural resources of fossil fuels a need arises to implement new power engineering technologies that allow carbon dioxide capture. Simultaneously, efforts are made to find new energy carriers which, if fired, do not involve carbon dioxide emissions. Hydrogen is one of such fuels with this future potential which is now becoming increasingly popular. Obviously, this means that the two gases mentioned above – carbon dioxide and hydrogen – will be produced in large quantities in future, which in many cases will necessitate their transport over considerable distances. If a pipeline failure occurs, the transport of the gases may pose a serious hazard to people in the immediate vicinity of the leakage site. This paper presents an analysis of the possibility of reducing the level of risk related to pipelines transporting CO₂ and H₂ by means of safety valves. It is shown that for a 50 km long and a 0.4 m diameter pipeline transporting gas with the pressure of 15 MPa the individual risk level can be reduced from 1·10⁻⁴ to 6.5·10⁻⁷ for CO₂ and from 1·10⁻⁶ to 6·10⁻¹⁰ for H₂. The social risk can be diminished in similar proportions.     

Database for accidents and incidents in the fuel ethanol industry

The purpose of the present research is to collect information about accidents and incidents that have occurred at fuel ethanol facilities from 1998 to October 2014, and to keep complete unified records of them in a database. The developed database contains general information about the accident or incident, its sequence, mitigation measures, its causes and consequences for humans, environment and for the plant. Until now, this information is not available. The work consisted in gathering information from different documental sources and subsequent organization in a database. It complements the previous work made for biodiesel industry and fills the existing gap in the field of ethanol. Knowledge about this information enables us to manage plant risks, since the accidents that are more likely to occur and the main sources of risk can be easily identified. Also, it makes it possible to exchange information with interested third parties. Statistical analysis shows that accident frequency has an oscillatory behavior, rising in the last year. Fire is the most common type of accident, while equipment mechanical failure is the main cause of accident. Partial material loss has been identified as the most common consequence. Finally, some conclusions are obtained concerning to the importance of having an updated and complete accident and incident database.     

Influence of concentration distribution of hydrogen in air on measured flammability limits

There is a clear difference between exiting data on the measured flammability limits of hydrogen-air mixture. The non-uniformity of concentration distribution of hydrogen in air is a contributor to deviations of the upper flammability limit (UFL) and the lower flammability limit (LFL) measured in different experiments. This paper presents a numerical model to simulate the gas mixing process from start to stability, to predict the concentration distribution, and to research the influence of concentration distribution of hydrogen in air on measured UFLs and LFLs. The commercial software package Fluent was used to carry out the numerical simulation for the concentration distribution of hydrogen in air in the vessels with length-to-diameter ratios (L: D) of 1:1, 3:1, 5:1 and 7:1 respectively. Based on the numerical simulation and analysis, the influence of concentration distribution on measured flammability limits was demonstrated for hydrogen in air in the vessel. It is found that the deviations of measured flammability limits of hydrogen in air are the minimum in the vessel with length-to-diameter ratio of 1:1, and augment with the augmentation of vessel length-to-diameter ratio. Moreover, it is presented that the deviations of measured flammability limits of hydrogen in the center of the vessel are lower than that in the top and the bottom.     

Numerical simulation of premixed methane–air deflagration in a semi-confined obstructed chamber

In this paper, large eddy simulation coupled with a turbulent flame speed cloure (TFC) subgrid combustion model has been utilized to simulate premixed methane–air deflagration in a semi-confined chamber with three obstacles mounted inside.The computational results are in good agreement with published experimental data, including flame structures, pressure time history and flame speed. The attention is focused on the flame flow field interaction, pressure dynamics, as well as the mechanism of obstacle-induced deflagration. It is found that there is a positive feedback mechanism established between the flame propagation and the flow field. The pressure time history can be divided into four stages and the pseudo-combustion concept is proposed to explain the pressure oscillation phenomenon. The obstacle-induction mechanism includes direct effect and indirect effect, but do not always occur at the same time.