基于AGA-PP的农村公共安全综合风险评价方法

为了构建一套有效评价农村公共安全风险的指标体系和评价方法,考虑农村环境承载力影响因素对农村公共安全的制约,围绕农村生态承载力、基础设施承载力、社会承载力和人口承载力4个维度,提出能够全面评价农村公共安全风险的指标体系和基于PP（projection pursuit,投影寻踪）模型的风险评价方法.在风险评价方法构建上,采用AGA（accelerated genetic algorithm,加速遗传算法）对PP模型进行改进,实现投影指标函数的快速优化,在此基础上,采用回归分析方法,将时间序列与一维投影值进行拟合,求得一维投影值的预测曲线,通过对一维投影值的预测,利用信息扩散理论将投影值所携带的风险信息扩散至设定的4个风险等级上,用风险熵计算农村环境承载力发展趋势,并借以评价农村公共安全的风险大小.结果表明:基于AGA-PP的评价方法能够最大限度暴露多维指标数据的结构特征.依据最佳投影方向获得的一维投影值与时间序列拟合后,其拟合精度达到0.027 1,较高的拟合精度保证了后续农村环境承载力风险熵值的可信度,这在一定程度上保证了农村公共安全风险评价的可靠性.研究显示,从农村环境承载力的视角评价农村公共安全风险能够很好地反映农村公共安全风险的现实状况和发展趋势.基于AGA-PP的农村公共安全评价方法简单有效,具有评价精度高且与实际吻合度高的特征,能够为公共安全管理部门提供决策依据和方法参考.      

论我国水生态的保护与修复:任务与对策

本文聚焦我国水生态保护与修复工作,结合长期实践,分析当前的形势和任务,指出了当前要着力解决的水生态问题主要是:在大坝上游,河流变湖库,生境变化导致生物物种变化;水库水流流速变缓,水体自净能力降低,导致富营养化及藻类水华。在大坝下游,清水下泄,冲刷下游河道导致局部河道河势变化较大;水库蓄水使坝下游春季水温下降、秋季水温升高,水温变化过程滞后;水库蓄水导致大坝下游的水文过程改变,水的流量、流速、流态发生变化。在河道(航道)整治工程中,裁弯取直,缩短水流在河道中的停留时间,河岸衬砌和硬化,减少水向沿河堤岸的渗透,在大降水和洪水时易造成涝灾和洪灾。在涉湖工程中,阻隔河湖,填湖造地。在明确存在问题和迫切需求的基础上,提出了切实可行的对策建议。当前水生态保护与修复要围绕一条主线,即"人要发展,鱼要生存"的"人鱼线",要采取"调、控、退、通、改、拆"的综合措施,即生态调度,控制水污染,退建还水、退田还湖,河湖连通,对已建涉水工程进行生态化改造,对在保护区、重点风景名胜区、特有鱼类栖息地修建的小型工程要采取坚决措施拆除,恢复原貌。     

Impact of climate change on food security of small islands: The case of Mauritius

This paper studies the implications of high food prices resulting from climate change on food security in small islands, using Mauritius as a case‐study. Climate change may adversely impact prices of agricultural commodities. The study derives and calculates the government costs and the welfare effects of an increase in the world price of rice on consumers in Mauritius. Using an equilibrium displacement model, this study finds that an increase in the price of rice by 35%, as predicted by the literature on climate change and rice prices, will result in an increase of 28.8% in government spending, representing the additional outlays to support the subsidy scheme for food security. Using 2012 as the baseline, the welfare analysis results suggest that consumer surplus for ration rice consumers increases by 626 million Mauritian Rupees (MUR) or US$18 million while consumer surplus decreases by MUR454 million (US$13 million) for basmati rice consumers.     

地铁隧道地震动力响应模拟试验研究

为研究地震荷载作用下隧道结构的动力响应,以指导隧道修建施工和衬砌支护,提高地铁隧道的整体抗震能力,采用理论分析、数值模拟和室内试验相结合的方法,对地铁隧道地震动力响应进行研究。选取沈阳地铁2号线某段隧道为工程背景,在理论分析地铁隧道地震动力响应的前提下,运用FLAC~(3D)数值软件模拟地铁隧道地震动力响应情况,地铁隧道两帮壁正负45°区域剪应力、主应力和位移最显著,监测点加速度变化趋势与输入地震波加速度时程曲线较为一致。在室内振动台试验中,地基土体表面峰值加速度明显比地基土体深部大,隧道两帮壁正负45°位置附近应变最大,振动停止后应变并未归零。数值模拟与室内试验研究结果较为吻合表明,由于人工波的地震烈度较现场波大,地铁隧道的地震扰动强烈;地铁隧道两帮壁正负45°区域地震动力响应剧烈,极易发生破坏。可根据这一现象有针对性地采取抗震措施,保证地铁隧道的安全、稳定。     

Food access,food security and community gardens in Rockford,IL

Urban agriculture projects seek to ameliorate issues of food access and food security for people living in areas with low access to fresh foods, including food deserts. Within this discourse, community gardens have been promoted as vehicles to reclaim unused urban space, produce food locally and connect populations to their food sources and larger community. A variety of community garden models exist; in the Midwestern city of Rockford, Illinois, many community gardens grow food for donation to food pantries as part of a programme to benefit socioeconomically disadvantaged persons in the city. However, the ability of these gardens to involve neighbourhood participants and provide the social capital-related benefits attributed to community gardens in the literature is uncertain. Here we examine community gardens in Rockford, IL to assess the extent to which they contribute to residents’ ability to obtain fresh produce as well as other social benefits. Data for this project come from a combination of interviews with gardeners, focus groups with food pantry users and a survey of pantry users. We find that while non-gardening community members are benefitting from the increased produce that the gardens provide, they are not receiving all of the social and communal benefits associated with actively participating in a garden.     

Humanitarian (in)security: risk management in complex settings

Attacks against humanitarian aid workers have received increasing attention in the media, particularly high-profile incidents such as those against the hospitals of Médecins Sans Frontières in Afghanistan, Syria, and Yemen. Concurrently, scholarly research has given rise to a number of articles, white papers, and books on humanitarian insecurity. Most of this work centres on external threats, neglecting the internal mechanisms that humanitarian organisations use to mitigate security situations. This paper builds on the existing literature by focusing on the decision-making processes of humanitarian organisations, drawing on data collected from 16 security managers or advisers. The findings reveal that several factors contribute to contextual uncertainty and complexity, including recipient perceptions, local government actions, the behaviour of other non-governmental organisations (NGOs) in the area, logistical issues, risk variance within a single location, and organisational mandate. Furthermore, the results indicate that NGOs utilise a combination of decision-making processes to determine how to manage security in high-risk environments.     

基于AHP-FUZZY与SVM理论电网雷害风险评估

为了对电网遭受雷击灾害风险进行研究,以高压输电线路多个雷害影响因子为出发点对其进行归类,解决了以单因子雷击跳闸率作为高压输电线路遭受雷害评价指标的不足。采用AHP(层次分析法)-FUZZY(模糊数学理论)对电网雷害风险展开评估分级,引入某地500 k V电网工程实例,成功将该地电网雷害风险等级定为Ⅲ级中等雷害风险。为验证AHP-FUZZY法对电网雷害风险进行评估的准确性及可靠度,采用SVM(支持向量机)理论对工程实例进行分析计算,结果相关性系数R2为0.932,预测错误率为0,表明本次风险评估是可靠的,能够为电网雷害风险研究提供较大的理论与实际支撑。     

The rains are disappointing us: dynamic vulnerability and adaptation to multiple stressors in the Afram Plains, Ghana

This paper builds on work on the dynamics of vulnerability and multiple stressors through a case study in the Afram Plains of the Eastern region in Ghana. A vulnerability framework is applied in the community of Mimkyemfre to identify and explain the multiple underlying political, socioeconomic and environmental forces that influence the ways in which people are exposed and sensitive to climate, and their capacities to adapt to changing conditions. The results of the study indicate that the community experiences a range of biophysical and socioeconomic conditions that contribute to its vulnerability. Vulnerability was found to change over time and in some cases was cyclical, in that certain actions taken for the purposes of adaptation were found to exacerbate existing vulnerabilities. Processes of vulnerability were also found to occur at several scales and were experienced unevenly at the community level. The findings of this assessment have important implications for the design and implementation of successful adaptation initiatives, both in Africa and elsewhere. In particular, they demonstrate the need to understand the social, economic and institutional challenges to development as a basis for any contemplation of adaptation to climate change.     

The role of rainfed agriculture in securing food production in the Nile Basin

A better use of land and water resources will be necessary to meet the increasing demand for food in the Nile basin. Using a hydro-economic model along the storyline of three future political cooperation scenarios, we show that the future of food production in the Basin lies not in the expansion of intensively irrigated areas and the disputed reallocation of water, but in utilizing the vast forgotten potential of rainfed agriculture in the upstream interior, with supplemental irrigation where needed. Our results indicate that rainfed agriculture can cover more than 75% of the needed increase in food production by the year 2025. Many of the most suitable regions for rainfed agriculture in the Nile basin, however, have been destabilized by recent war and civil unrest. Stabilizing those regions and strengthening intra-basin cooperation via food trade seem to be better strategies than unilateral expansion of upstream irrigation, as the latter will reduce hydropower generation and relocate, rather than increase, food production.     

Cars and fuels for tomorrow: a comparative assessment

Light duty vehicles, i.e. passenger cars and light trucks, account for approximately half of global transportation energy demand and, thus, a major share of carbon dioxide and other emissions from the transport sector. Energy consumption in the transport sector is expected to grow in the future, especially in developing countries. Cars with alternative powertrains to internal combustion engines (notably battery, hybrid and fuel-cell powertrains), in combination with potentially low carbon electricity or alternative fuels (notably hydrogen and methanol), can reduce energy demand by at least 50%, and carbon dioxide and regulated emissions much further. This article presents a comparative technical and economic assessment of promising future fuel/vehicle combinations. There are several promising technologies but no obvious winners. However, the electric drivetrain is a common denominator in the alternative powertrains and continued cost reductions are important for widespread deployment in future vehicles. Development paths from current fossil fuel based systems to future carbon-neutral supply systems appear to be flexible and a gradual phasing-in of new powertrains and carbon-neutral fluid fuels or electricity is technically possible. Technology development drivers and vehicle manufacturers are found mainly in industrialised countries, but developing countries represent a growing market and may have an increasingly important role in shaping the future.