我国城市建设用地利用效益评价

从土地利用的综合效益出发。采用因子分析方法从经济、社会、环境等多角度对现阶段我国各省（区、市）城市建设用地的综合利用效益进行了定量化评价。研究结果显示，土地利用效益偏低的省份为18个，占60％，主要分布在中西部地区，利用效益较高的省份为7个。主要位于东部沿海等地。本研究方法克服了以往单因素评价方法的不足，即片面追求经济总量不一定实现土地资源可持续高效利用。同时，为从空间角度调控土地利用效益提供了一定的政策建议。     

论国家发展战略的选择--转移、转嫁与转变

从全人类和长暑期的角度来看，可持续发展是人类社会发展的必然，但在短时期内，特别是在特定的的国家和地区范围内，却不一定是必然的。这种必然性的实现领带于各国政府对国家发展战略的选择。本文在分析先期工业化国家发展路径的基础上，提出了国家发展路径的几种可能情形．论述了发展路径依赖于政府负责任的赖选择关系，并初步分析了可能的选择空间。最后．论文指出中国的科学发展观是超越了转移、转嫁的发展模式的转变．是对人类社会负责任的符合可持续发展要求的战略选择。     

南方水土流失区开发治理的思路——日本漆树引种

水土流失区采用综合防治措施取得了水土保持的良好综合效益，在市场经济条件下，在综合效益中，社会效益和生态效益比较，人们更重视经济效益。兴办经济实体，对水土流失区进行开发型治理，已成为人们的普遍要求。开发型治理模式是传统综合模式的提高，它要求有足够的基础投入；要有高素质的管理人才和技术，要选准开发对象，变水土保持重声势重规模为重管理重效益，因而其三大效益将有显著提高。宁都县漆树开发引种初露成效。     

南水北调工程及其生态安全：优先研究领域

南水北调工程的实施将大幅度增加黄河上游径流量，并同时减少长江尤其是其上游及汉江下游的径流量，从而导致两条主要河流及其支流的水环境改变。中线工程从汉江上游丹江口水库调水，库区上游90 000余km2内的非点源污染和1 300万人口的生活污水处理设施的缺乏对水质将产生重大影响;调水引起水文节律的改变从而对东线沿途的湖泊生态系统产生重大影响;黄淮海平原受水区可利用水量的增加也可能导致该地区的盐渍化。介绍了南水北调工程并讨论了其必要性，提出了工程对生物迁移的影响、水环境及水生态安全、水资源保护的流域生态系统管理和西部退化生态系统的恢复和重建等优先研究领域，并提出结合“中国生态系统研究网络”、“生态环境国家野外科学观测研究站”的建设和长期监测来保障工程生态安全的策略。     

Confronting Uncertainty and Missing Values in Environmental Value Transfer as Applied to Species Conservation

Abstract: The nonuse (or passive) value of nature is important but time‐consuming and costly to quantify with direct surveys. In the absence of estimates of these values, there will likely be less investment in conservation actions that generate substantial nonuse benefits, such as conservation of native species. To help overcome decisions about the allocation of conservation dollars that reflect the lack of estimates of nonuse values, these values can be estimated indirectly by environmental value transfer (EVT). EVT uses existing data or information from a study site such that the estimated monetary value of an environmental good is transferred to another location or policy site. A major challenge in the use of EVT is the uncertainty about the sign and size of the error (i.e., the percentage by which transferred value exceeds the actual value) that results from transferring direct estimates of nonuse values from a study to a policy site, the site where the value is transferred. An EVT is most useful if the decision‐making framework does not require highly accurate information and when the conservation decision is constrained by time and financial resources. To account for uncertainty in the decision‐making process, a decision heuristic that guides the decision process and illustrates the possible decision branches, can be followed. To account for the uncertainty associated with the transfer of values from one site to another, we developed a risk and simulation approach that uses Monte Carlo simulations to evaluate the net benefits of conservation investments and takes into account different possible distributions of transfer error. This method does not reduce transfer error, but it provides a way to account for the effect of transfer error in conservation decision making. Our risk and simulation approach and decision‐based framework on when to use EVT offer better‐informed decision making in conservation.     

Numerical Analysis of Heat Transfer and Gas Flow in PEM Fuel Cell Ducts by a Generalized Extended Darcy Model

Abstract

In this work, gas flow and heat transfer have been numerically investigated and analyzed for both cathode/anode ducts of proton exchange membrane (PEM) fuel cells. The simulation is conducted by solving a set of conservation equations for the whole domain consisting of a porous medium, solid structure, and flow duct. A generalized extended Darcy model is employed to investigate the flow inside the porous layer. This model accounts for the boundary-layer development, shear stress, and microscopic inertial force as well. Effects of inertial coefficient, together with permeability, effective thermal conductivity, and thickness of the porous layer on gas flow and heat transfer are investigated.     

Electrostatic ignition hazards in insulating or dissipative tubes and hoses for pneumatic transfer of powders—Measurements and model calculations

When transferring powder through pipes or hoses made from insulating material, propagating brush discharges cannot be excluded. To calculate the limit value of the resistivity of the insulating material, below which no propagating brush discharges will occur, the charging current due to the powder transfer must be known. This charging current has been determined experimentally. Based on analytical calculations and computer models limit values for the resistivity of the hose material are derived from these experiments.     

Trophy hunters’ willingness to pay for wildlife conservation and community benefits

In the face of fundamental land‐use changes, the potential for trophy hunting to contribute to conservation is increasingly recognized. Trophy hunting can, for example, provide economic incentives to protect wildlife populations and their habitat, but empirical studies on these relationships are few and tend to focus on the effects of benefit‐sharing schemes from an ex post perspective. We investigated the conditions under which trophy hunting could facilitate wildlife conservation in Ethiopia ex ante. We used a choice experiment approach to survey international trophy hunters’ (n = 224) preferences for trips to Ethiopia, here operationalized as trade‐offs between different attributes of a hunting package, as expressed through choices with an associated willingness to pay. Participants expressed strong preferences and, consequently, were willing to pay substantial premiums for hunting trips to areas with abundant nontarget wildlife where domestic livestock was absent and for arrangements that offered benefit sharing with local communities. For example, within the range of percentages considered in the survey, respondents were on average willing to pay an additional $3900 for every 10 percentage points of the revenue being given to local communities. By contrast, respondents were less supportive of hunting revenue being retained by governmental bodies: Willingness to pay decreased by $1900 for every 10 percentage points of the revenue given to government. Hunters’ preferences for such attributes of hunting trips differed depending on the degree to which they declared an interest in Ethiopian culture, nature conservation, or believed Ethiopia to be politically unstable. Overall, respondents thus expressly valued the outcomes of nature conservation activities—the presence of wildlife in hunting areas—and they were willing to pay for them. Our findings highlight the usefulness of insights from choice modeling for the design of wildlife management and conservation policies and suggest that trophy hunting in Ethiopia could generate substantially more financial support for conservation and be more in line with conservation objectives than is currently the case.     

Barriers to implementing sustainability locally: a case study of policy immobilities

This study aims to contribute to the field of urban planning by applying policy mobilities and transfer theories to a case study of the Capital Regional District and its 13 municipalities in British Columbia, Canada, in order to analyse and understand the dynamics of how sustainability is governed locally, with a special focus on barriers to sustainability policy mobility. The empirical material is primarily based on interviews with key stakeholders who guide policy development and creation in the region to inform an understanding of how sustainable development initiatives are developed and shared. This study finds that while there is interest and demand in sustainability, policy-makers are frustrated with their lack of success in implementing sustainability programmes. While there are some instances of policy sharing and transfer among municipalities in the region, there is a clear desire for more exchanges which would allow municipalities to respond more effectively to the demands placed upon them. Significant barriers to policy mobility are also identified, in particular, an unclear understanding of sustainability, a culture of competition and hostility among municipalities, difficulty with the process of transfer itself, and a lack of time, money and resources. These barriers are in part a result of a broken governance structure which does not provide clear leadership to the municipalities, sets municipalities to be competitive with each other and provides ineffective support for municipalities through an unwieldy regional administrative body which is not well regarded by the municipalities.     

Photostabilization of the botanical insecticide azadirachtin in the presence of lecithin as UV protectant

Abstract

The phytochemical insecticide, azadirachtin (AZ), undergoes UV‐induced photodegradation. Using the isomer AZ‐A as a standard, its photochemical stability was studied with and without adding lecithin surfactant as a UV protectant. Standard solutions of pure AZ‐A and Margosan‐O^® were prepared in methanol‐hexane with (AZ‐A:lecithin, 1:2 by weight) and without lecithin, applied separately onto glass plates and maple (Acer L.) foliage and exposed to radiant energy under controlled conditions. Noticeable photostabilization of AZ‐A was achieved in the samples containing lecithin compared to AZ‐A samples without the lecithin additive. First‐order kinetic evaluation of the data showed that the DTy₅₀ (half‐life) and C (rate constant) values for AZ‐A with and without lecithin on glass plates were 5.68 d and 0.122, and 5.42 d and 0.128, respectively. The corresponding values for the Margosan‐0 formulation were 7.37 d and 0.094, and 6.24 d and 0.111. The DT₅₀ and C values for the pure AZ‐A on maple foliage with and without lecithin were 8.77 d and 0.079, and 6.54 d and 0.106, respectively. The corresponding values for the Margosan‐0 formulation on foliage were 8.35 d and 0.083, and 7.45 d and 0.093. The kinetic data gave quantitative information regarding the photostabilization of AZ‐A in the presence of lecithin. Good UV protection can only be achieved if the additive has the matching X_max of AZ‐A. The mechanism of photostabilization of AZ‐A in the presence of lecithin was due to either energy transfer from the excited AZ‐A to lecithin and/or competitive absorption of UV photons by the latter.