抽出式通风煤巷掘进过程中粉尘浓度分布规律的数值模拟

根据气固两相流理论，针对矿井掘进工作面的特点，采用计算流体力学的离散相模型（DPM）对掘进工作面通风过程中粉尘浓度进行数值模拟，总结抽出式通风掘进巷道中粉尘浓度的沿程分布及变化规律。     

TRANSIENT RESPONSE FUNCTIONS FOR CONJUNCTIVE WATER MANAGEMENT IN THE SNAKE RIVER PLAIN,IDAHO1

ABSTRACT: Increasing demands on western water are causing a mounting need for the conjunctive management of surface water and ground water resources. Under western water law, the senior water rights holder has priority over the junior water rights holder in times of water shortage. Water managers have been reluctant to conjunctively manage surface water and ground water resources because of the difficulty of quantification of the impacts to surface water resources from ground water stresses. Impacts from ground water use can take years to propagate through an aquifer system. Prediction of the degree of impact to surface water resources over time and the spatial distribution of impacts is very difficult. Response functions mathematically describe the relationship between a unit ground water stress applied at a specific location and stream depletion or aquifer water level change elsewhere in the system. Response functions can be used to help quantify the spatial and temporal impacts to surface water resources caused by ground water pumping. This paper describes the theory of response functions and presents an application of transient response functions in the Snake River Plain, Idaho. Transient response functions can be used to facilitate the conjunctive management of surface and ground water not only in the eastern Snake River Plain basin, but also in similar basins throughout the western United States.     

ARE RURAL RESIDENTS WILLING TO PAY ENOUGH TO IMPROVE DRINKING WATER QUALITY?1

ABSTRACT: The concentrations of iron and sulfate in community water supplies are a concern for a number of areas in southwestern Minnesota. This study used the contingent valuation method to determine how much consumers would be willing to pay to improve their drinking water quality. On average, individuals were willing to pay US$5.25 per month (in 1995 U.S. dollars) to reduce the level of iron and US$4.33 per month to reduce the level of sulfate in their water to the USEPA's secondary standards for drinking water quality. Respondents with negative perceptions of their drinking water quality were willing to pay more to improve water quality. The aggregate annual willingness to pay (WTP) for all consumers in community water systems in southwestern Minnesota that were out of compliance with water quality standards were estimated to be US$2.4 million and US$2.0 million (in 1995 dollars) for reducing the levels of iron and sulfate, respectively. Yet the total WTP of consumers who use small community water systems may not be enough to pay the full cost of providing improved water in those systems. Economies of scale in water treatment and difficulties in financing improvements mean that technical innovation, government assistance, or institutional changes may be needed to improve water quality in these areas.     

安全降变原理及C-S-R事故致因新模型

为发展安全科学原理和给事故防控与调查提供新的方法,根据变化对系统安全的影响机制,开展安全降变原理及事故致因新模型研究。首先,提出安全降变原理并解析其内涵及研究意义。其次,基于安全降变原理,给出不同层级安全系统变化的分类实例,并对作业场所事故及其致因重新定义和分类。再次,构建基于安全降变原理的C-S-R事故致因新模型。最后,基于事故案例分析,验证所提出的C-S-R事故致因新模型与安全降变原理的有效性。结果表明,各级安全系统中自发或是受联动的变化超出系统的变化承受水平时,将导致事故的发生。经事故案例分析验证可知,安全降变原理及C-S-R事故致因新模型具有充分的实用性。     

政府调控、市场机制与城市发展

深入探究政府调控和市场机制对城市规模的影响有利于解决目前中国大城市人口快速膨胀,城市病频发,而中小城市发展潜力不足,对人口吸纳能力有限,城市发展规模存在两极分化的问题。从探究影响城市发展的因素入手,通过对不同地区和不同规模城市的面板数据回归分析,发现中国属于典型的"自上而下"的城市发展模式,尤其是城市科层制的层级结构直接决定了城市规模大小,政府财政分权行为更加剧了城市规模两极分化趋势。市场机制对城市规模具有一定的影响,但其作用方向和效果明显依赖于政府调控水平,且科层制的城市等级结构弱化了市场机制对城市规模影响效果的发挥。政府和市场机制对不同区域、不同规模城市的影响效应不同。市场机制在东部城市产生涓流效应,而在中西部则发挥着聚集极化作用。市场机制在特大和大城市已产生涓流效应,加之政府"抑大崇小"的城市发展战略使得这种效应愈加明显,中等城市则处于极化效应和涓流效应更替中,小城市则表现为更多的聚集极化效应。为形成大中小城市合理分工的城市体系,其关键在于正确处理政府调控和市场机制的关系。政府应指导城市发展方向,为其创造良好的宏观环境,市场则应在微观资源配置中起决定性作用。建议根据城市发展和市场经济需要,对现有的行政区划进行适时调整和变动。调整公共资源在特大及大中小城市传统分配政策,实现公共资源由按行政级别配置向按照人口规模配置转变。同时,建立跨区域的相应的协调机制,以市场力量突破行政界限探索城市健康发展。     

Parks versus PES: Evaluating direct and incentive-based land conservation in Mexico

Protected areas (PAs) and payments for ecosystem services (PES) are the top two mechanisms available for countries to achieve international REDD agreements, yet there are few empirical comparisons of their effects. We estimate the impacts of PAs and PES on forest conservation, poverty reduction, and population change at the locality level in Mexico in the 2000s. Both policies conserved forest, generating an approximately 20–25% reduction in expected forest cover loss. PES created statistically significant but small poverty alleviation while PAs had overall neutral impacts on livelihoods. Estimates by individual policy type for the same level of deforestation risk indicate that biosphere reserves and PES balanced conservation and livelihood goals better than strict protected areas or mixed-use areas. This suggests that both direct and incentive-based instruments can be effective, and that policies combining sustainable financing, flexible zoning, and recognition of local economic goals are more likely to achieve conservation without harming livelihoods.     

福建省地级市人为源活性氮排放及其特征分析

在人口增长和快速城市化的背景下,活性氮排放对生态环境的影响日益加剧.为研究省级尺度活性氮排放规律,采用排放因子法建立2000、2005及2010年福建省人为源活性氮排放清单,分析各地市3个年份活性氮排放量及排放强度特征.结果表明,3个年份福建省活性氮排放总量分别为538.4、587.0和619.97 Gg,呈整体增加趋势.在9个地级市中,增速最快的为莆田市,而漳州市排放量有所下降.排放量最大的为漳州和泉州,排放量最小的为宁德与厦门.从排放来源看,90%以上的排放来自农田生态系统和畜禽养殖系统.能源活动贡献较小,但其排放增长最为显著.2010年,各地市单位面积活性氮排放强度呈"东南沿海高西北内陆低"的格局,最高为厦门市,最低为三明市;GDP和人口排放强度则呈"东南沿海低西北内陆高"的格局,最高为南平市,最低为厦门市.在分析各地市活性氮排放源特征的基础上,探讨了不同地区活性氮减排重点,研究结果可为福建省及下辖各地市活性氮减排提供科学依据.     

大型底栖动物生物评价指数比较与应用

采用不同生物指数评价河流健康,结果往往有差异,如何识别各种生物指数的关系和适用性成为亟待解决的问题.基于太子河流域大型底栖动物群落研究,比较了5种大型底栖动物生物指数评价结果的差异.结果表明,5种指数具有极显著的相关性,但由于健康等级划分标准差异,造成不同指数的健康评价等级存在一定差异.同时分析了不同指数对不同类型人为活动影响的敏感性,研究其在河流健康评价中的适用性.结果表明在太子河流域中,BI指数与土地利用类型和溶氧具有较好的相关关系,对这两类的干扰具有较好的指示作用;FBI指数对酸污染和氨氮污染具有较强的指示作用;ASPT指数与耗氧相关的水质指标有较强的负相关;B-IBI指数与总氮呈显著的负相关关系,可较好指示氮污染,而且B-IBI指数与其他类型人为干扰活动均呈显著的相关关系,对土地利用和水质污染也具有较好的指示作用.综上所述,大型底栖动物BI指数和ASPT指数应该分别适用于评价流域土地利用和水化学指标对河流生态系统的影响,而B-IBI可用于评估多种类型人为干扰活动.     

中国区域环境绩效及波特假说的再检验

以二氧化碳为非期望产出,基于序列DEA的方向性距离函数、环境规制强度指数、Malmqulist-Luenberger指数,测度了1999~2010年中国30个省、市、自治区及东、中、西、东北四大区域的环境技术效率、环境规制成本及全要素生产率,并对四大区域的全要素生产率进行了波特假说的再检验.研究结果表明:区域间的环境技术效率呈现东-东北-中-西依次递减的演变格局;东北老工业基地的环境规制成本最高、西部地区最低;环境规制强度与全国及四大区域全要素生产率有显著的正相关性,这支持了波特假说的存在;技术进步效应的检验结果显示,只有中部区域支持波特假说的存在,西部区域检验结果表明碳排放的规制过高会对技术进步带来消极影响;环境技术效率变化效应的检验结果显示,全国及四大区域均支持波特假说的存在,碳排放规制强度的加强,会推动各地区在不同时期追赶最优生产前沿面的程度.     

飞机环控系统典型故障分析

环控系统解决了飞机座舱的供气、调温和增压问题,座舱的压力制度按3个阶段进行。通过典型的飞机环控系统故障,对座舱压力调节机理进行了分析,介绍了座舱压力调节过程,分析了导致飞行员耳膜疼痛、座舱压力持续下降的原因,提出了预防故障发生的建议。