Anthropogenic NOx emissions alter the intrinsic water-use efficiency (WUEi) for Quercus cerris stands under Mediterranean climate conditions

We investigated the effect of N deposition (Ndep) on intrinsic water-use efficiency (WUE_i), the ratio of photosynthesis (A) to stomatal conductance (g_s), for two Quercus cerris stands at different distances to an oil refinery in Southern Italy. We used δ¹³C in tree rings for assessing changes in WUE_i; while the influence of climate and NO_x emission was explored through δ¹⁸O and δ¹⁵N, respectively. Differences in WUE_i between the two sites were significant, with trees exposed to different degrees of NO_x emissions showing an abrupt increase with the onset of pollution. Assuming similar g_s at the two sites, as inferred through δ¹⁸O, the higher N availability at the polluted site caused the shift of the A/g_s ratio in favour of A. Overall, our result suggests that an increase of Ndep may enhance tree WUE under a scenario of reduction of precipitation predicted for Mediterranean area.     

营区雨水集蓄利用效果评价模糊数学模型

本文以研究营区内雨水集蓄利用效果为目的。分析雨水集蓄利用不同方法,通过建立合理模糊数学模型,对各种雨水集蓄利用方法进行权重比较,得出最优结果。并将该模型用在营区雨水集蓄利用效果的评价分析,通过运算结果确定营区内雨水利用效果的优、良、中、差。通过运用模糊数学模型对营区内雨水集蓄利用方法进行分析,综合评价营区内雨水集蓄利用结果为良好。     

云南省耕地生产效率的时空差异及影响因素

以第二次全国土地调查完成以来的2009~2013年为研究时段,在测算云南省16个州(市)的耕地生产效率基础上,综合运用ESDA技术、基尼系数等方法系统分析云南省耕地生产效率的时空差异,并构建计量经济模型研究影响不同区域耕地生产效率变化的主要因素。结果表明:(1)2009~2013年,云南省耕地生产效率呈总体上升趋势,但增幅逐年降低;效率低值地区增长明显,高值地区则并不显著;(2)云南省耕地生产效率区域差异呈缩小态势,并表现出由西南向东北递减的空间分布特征;(3)滇中、滇西南等粮食主产区受≤6°耕地面积比重、旱涝保收面积的影响较大,而滇东地区则更易受到6°坡耕地面积和人均GDP的影响,滇西北地区受≤6°耕地面积比重和人均GDP的影响显著。     

Maximum power point tracking methods for photovoltaic systems operating under partially shaded or rapidly variable insolation conditions: a review paper

To increase the efficiency of photovoltaic (PV) systems, maximum power point (MPP) tracking of the solar arrays is needed. Under partially shaded conditions (PSCs), the solar arrays power–current (P–I) characteristic has multiple MPP. This paper presents various methods and approaches of tracking the MPP from a PV generator operating under PSC. Some comparisons, advantages, drawbacks and critical analysis of each method are discussed. It was found that, indirect methods use empirical data or mathematical expressions of numerical approximations to estimate the MPP from the PV generator’s voltage, current and irradiance. Direct methods offer the advantage of obtaining the actual maximum power from the PV generator’s voltage and current. Artificial intelligence methods do not need exact mathematical models. They can perform under parameter variation, load and supply voltage disturbances. Finally, novel methods require less number of iterations to converge, independent to the initial conditions. All these algorithms can be included in some of the DC/DC converters and MPP trackers for stand-alone or grid-connected systems.     

湿法烟气脱硫反应过程的实验研究

在石灰石/石膏湿法烟气脱硫中试台上,系统开展了浆液pH值、飞灰浓度、液气比、入口SO2浓度、烟气速度和氧化方式等对脱硫反应过程影响的实验研究。实验表明,脱硫效率随着石膏浆液pH值、液气比的升高而增加,且入口SO2浓度越高,液气比越低,影响效应越明显;脱硫效率随着烟气速度、烟气温度和入口SO2浓度的增加而下降;石膏浆液中飞灰含量对系统脱硫效率具有一定的促进作用:pH值>5.6,飞灰浸出液中Fe3+含量相对较低,Fe3+对脱硫反应过渡态催化氧化影响程度较轻,不同工况脱硫效率差别不大。pH值<5.6,飞灰浸出液中Fe3+含量随pH值降低而增大,增效效果逐渐显著;氧化方式对脱硫反应过程有明显的影响,强制氧化工艺的脱硫效率比自然氧化的高5%左右。     

Fog as a Fresh-Water Resource: Overview and Perspectives

The collection of fog water is a simple and sustainable technology to obtain fresh water for afforestation, gardening, and as a drinking water source for human and animal consumption. In regions where fresh water is sparse and fog frequently occurs, it is feasible to set up a passive mesh system for fog water collection. The mesh is directly exposed to the atmosphere, and the foggy air is pushed through the mesh by the wind. Fog droplets are deposited on the mesh, combine to form larger droplets, and run down passing into a storage tank. Fog water collection rates vary dramatically from site to site but yearly averages from 3 to 10 l m⁻² of mesh per day are typical of operational projects. The scope of this article is to review fog collection projects worldwide, to analyze factors of success, and to evaluate the prospects of this technology.     

北京市城市生活垃圾收运系统研究

对北京市城市生活垃圾收运系统现状进行了全面的分析,对北京城八区生活垃圾收集、分类收集、转运、生活垃圾处理设施和垃圾物流现状进行了分析,同时对北京市城市生活垃圾收运系统进行了分析,指出了北京市城市生活垃圾收运系统存在的主要问题和今后改进的建议及处理处置设施的规划,为北京城市生活垃圾收运系统的建设和完善起到了积极地推动作用。     

欠发达地区农户生产效率研究——以西藏自治区为例

以西藏自治区为例,在2009年农户抽样调查数据基础上,利用数据包络法(DEA)探讨西藏不同区域农户生产效率,认为西藏农户生产效率差异与农业生产中自用价值的计算有关,若考虑自用价值,在固定生产规模报酬(CRS)假设下,平均生产效率为0.653,其中拉萨市最高(0.784),日喀则市最低(0.277);若不计入自用价值,山南与那曲地区呈现最高生产效率。表明西藏农户收入中自用价值占了较大比例,扣除自用价值,收入大幅减少,影响生产效率。因此,提高农牧户生产商品率是增加农牧民收入的有效途径。     

基于纳污红线的河流排污权优化分配模型

实行水功能区限制纳污红线的水资源管理制度,在理论和实践中必须要建立河流污染物总量控制管理制度,而实行污染物总量控制,首先要确定河流排污权的初始分配方案。结合我国现行流域水功能区划成果,以水功能区作为排污权初始分配主体开展排污权分配研究,提出由河流环境保护部门确定河流总体排污权,首先通过纵向配置将排污权分配给水功能区,然后通过横向配置将初始排污权分配给排污者的一种纵向加横向分配模式。以资源分配的公平性和效率为管理目标,并以污染物总量控制、浓度控制、企业生产连续性等为约束条件,建立了河流排污权多目标分配优化模型。最后利用多目标演化算法对算例进行了求解,验证了方法的可行性,且此分配方式所获得的环境节余容量最大     

微生物燃料电池在污水处理中的研究进展

微生物燃料电池（Microbial Fuelcell,MFC）是一种以微生物为催化剂,将有机物中的化学能转化为电能的装置。本文介绍了微生物燃料电池的原理和特点,阐述了反应器结构、底物种类、电极等方面的研究进展,分析了微生物燃料电池未来的发展方向,并对今后的研究提出建议。