有限水域棒束附连水质量计算方法

目的给棒束型核反应堆等类似结构的抗冲击性能设计提供一定理论依据。方法首先通过势流理论计算得出单棒速度势,再利用泰勒展开和坐标变换数学方法计算得出棒束在流体中产生的总势,继而导出棒束的附连水质量。结果从公式中获得了棒束附连水质量与棒距边界距离、棒间距、棒数及棒各阶模态之间的相互关系。结论该公式经有限元仿真计算和试验验证是合理的,可作为棒束型反应堆等类似结构抗冲击设计的依据。     

离子型稀土尾矿残留铵缓释性分析

为探究尾矿残留NH₄⁺的缓释性,以江西信丰离子型稀土矿为研究对象,柱浸制备浸出尾矿,去离子水淋洗尾矿.按照淋洗→封存→再淋洗的步骤,考察了淋洗尾矿不同含水率（1.3%,15%,35%,250%）,不同封存时间（15,30,60,120,180,195,210,240d）和不同传质机制（对流、扩散）下NH₄⁺的淋出量.结果表明：尾矿再淋洗仍能淋出NH₄⁺,NH₄⁺淋出量受含水率、封存时间和传质方式影响;含水率≥15%时,NH₄⁺淋出量整体随时间推移而递增;同时间下,NH₄⁺淋出量整体随含水率增大而增大;其他条件相同时,对流传质下NH₄⁺淋出量大于扩散.尾矿再次淋出的NH₄⁺是可交换态NH₄⁺向水溶态NH₄⁺转化的结果.     

Value of information analysis: the state of application

The value of information (VoI) is a decision analytic method for quantifying the potential benefit of additional information in the face of uncertainty. This paper reviews the prevalence of VoI applications reported in the peer-reviewed literature from the years 1990–2011. We categorize papers’ applications across the types of uncertainties considered, modeling choices, and contexts of social importance (such as health care and environmental science). We obtain and analyze statistics on the range of applications and identify trends and patterns in them, and conclude with an interpretation of what these mean for researchers and practitioners as they pursue new efforts. Key results include a substantial increase over the last 20 years in published papers utilizing VoI, particularly in the medical field. Nineteen trends in VoI applications from the period of 1990–2000 to 2001–2011 were found to be at least weakly significant. Beyond simple trends, some characteristics of VoI usage depend on the area of application, and in some cases, certain sets of characteristics tend to be found together.     

Public Acceptance of Wildland Fire and Fuel Management: Panel Responses in Seven Locations

Wildland fire affects both public and private resources throughout the United States. A century of fire suppression has contributed to changing ecological conditions and accumulated fuel loads. Managers have used a variety of approaches to address these conditions and reduce the likelihood of wildland fires that may result in adverse ecological impacts and threaten communities. Public acceptance is a critical component of developing and implementing successful management programs. This study examines the factors that influence citizen support for agency fuel reduction treatments over time—particularly prescribed fire and mechanical vegetation removal. This paper presents findings from a longitudinal study examining resident beliefs and attitudes regarding fire management and fuels treatments in seven states: Arizona, Colorado, Oregon, Utah, Michigan, Minnesota, and Wisconsin. The study was implemented in two phases over a 6-year period using mail surveys to residents of communities adjacent to federal lands in each location. Questions replicated measures from the original project as well as some new items to allow a more in-depth analysis of key concepts. The study design enables comparisons over time as well as between locations. We also assess the factors that influence acceptance of both prescribed fire and mechanical vegetation removal. Findings demonstrate a relative stability of attitudes toward fuels management approaches over time and suggest that this acceptance is strongly influenced by confidence in resource managers and beliefs that the treatments would result in positive outcomes.     

对建立广西生态补偿机制的探讨

广西地处生态脆弱和敏感地区,经济发展相对落后,生态环境与经济发展平衡问题亟须解决。从广西生态补偿实践来看,在取得成效的同时存在补偿资金少、补偿效率低和缺乏统一规范的管理等问题,基于这些问题提出了适合广西的生态补偿办法,为构建广西生态补偿机制建言献策。     

The emergence of climate change adaptation as a policy field: the case of England

Attention toward climate adaptation has been growing among governments over the past decade. In the European Union (EU) alone, nine countries have national plans for adaptation (with more in preparation), there are some 30 sub-national plans, and every Member State has policies to address adaptation. Given the recent attention given toward this subject a question that arises is: can climate change adaptation be considered a policy field? As a unit of analysis, policy fields are widely studied in the social sciences. However, the definition of policy fields such as environmental policy or agricultural policy is taken for granted. Oddly for such a common concept, very little attention is paid to what policy fields are in and of themselves or how they can be identified. Given these shortcomings, this article first attempts to fill this gap by theoretically defining what a policy field is by identifying and assigning their characteristics and dynamics. Based upon a literature review, it shows that policy fields are three-dimensional entities comprised of substantive authority, institutional order, and substantive expertise. The second task of this article is to apply this definition to adaptation policy activity in England and determine whether adaptation can be considered a policy field there.     

Climate engineering and climate tipping-point scenarios

Many scientists fear that anthropogenic emissions of greenhouse gases have set the Earth on a path of significant, possibly catastrophic, changes. This includes the possibility of exceeding particular thresholds or tipping points in the climate system. In response, governments have proposed emissions reduction targets, but no agreement has been reached. These facts have led some scientists and economists to suggest research into climate engineering. In this paper, we analyze the potential value of one climate engineering technology family, known as solar radiation management (SRM) to manage the risk of differing tipping-point scenarios. We find that adding SRM to a policy of emissions controls may be able to help manage the risk of climate tipping points and that its potential benefits are large. However, the technology does not exist and important indirect costs (e.g., change in precipitation) are not well understood. Thus, we conclude the SRM merits a serious research effort to better understand its efficiency and safety.     

DETERMINANTS OF LANDOWNER'S WILLINGNESS TO PAY FOR FLOOD HAZARD REDUCTION1

ABSTRACT: Estimated benefits of flood control projects are typically limited to avoided property damages. However, the possibility that there are (1) benefits from reduced psychological stress among flood plain occupants, and (2) benefits to the community has long been recognized. A survey of landowners residing in a flood plain in Roanoke, Virginia, found that nonproperty considerations did help explain their expressed willingness to pay for flood control. Of particular importance was the respondents' concern for disruption of the community caused by possible flooding.     

Hot steam transfer through heat protective clothing layers.

The aim of this study was to analyse the transfer of steam through different types of textile layers as a function of sample parameters such as thickness and permeability. In order to simulate the human body, a cylinder releasing defined amounts of moisture was also used. The influence of sweating on heat and mass transfer was assessed. The results show that in general impermeable materials offer better protection against hot steam than semi-permeable ones. The transfer of steam depended on the water vapour permeability of the samples, but also on their thermal insulation and their thickness. Increasing the thickness of the samples with a spacer gave a larger increase in protection with the impermeable samples compared to semi-permeable materials. Measurements with pre-wetted samples showed a reduction in steam protection in any case. On the other hand, the measurements with a sweating cylinder showed a beneficial effect of sweating.     

Diurnal and weekday variations in the source contributions of ozone precursors in California's South Coast Air Basin

For at least 30 years, ozone (O3) levels on weekends in parts of California's South Coast (Los Angeles) Air Basin (SoCAB) have been as high as or higher than on weekdays, even though ambient levels of O3 precursors are lower on weekends than on weekdays. A field study was conducted in the Los Angeles area during fall 2000 to test whether proposed relationships between emission sources and ambient nonmethane hydrocarbon (NMHC) and oxides of nitrogen (NOx) levels can account for observed diurnal and day-of-week variations in the concentration and proportions of precursor pollutants that may affect the efficiency and rate of O3 formation. The contributions to ambient NMHC by motor vehicle exhaust and evaporative emissions, estimated using chemical mass balance (CMB) receptor modeling, ranged from 65 to 85% with minimal day-of-week variation. Ratios of ambient NOx associated with black carbon (BC) to NOx associated with carbon monoxide (CO) were approximately 1.25 +/- 0.22 during weekdays and 0.76 +/- 0.07 and 0.52 +/- 0.07 on Saturday and Sunday, respectively. These results demonstrate that lower NOx emissions from diesel exhaust can be a major factor causing lower NOx mixing ratios and higher NMHC/NOx ratios on weekends. Nonmobile sources showed no significant day-of-week variations in their contributions to NMHC. Greater amounts of gasoline emissions are carried over on Friday and Saturday evenings but are, at most, a minor factor contributing to higher NMHC/NOx ratios on weekend mornings.