Methane emissions from terrestrial plants over China and their effects on methane concentrations in lower troposphere

Methane (CH₄) is the most important greenhouse gas and reactive trace gas in the atmosphere. Recently, it has been reported that terrestrial plants can emit CH₄ under aerobic conditions, which may call for reevaluation of the inventory of CH₄ emissions in China. In this paper, those emissions over China and their effects on CH₄ concentrations in lower troposphere were investigated. Firstly, based on the work of Keppler et al., the aerobic plant CH₄ emission model (PLANTCH4) for China was established. And by using the database of normalized difference vegetation index (NDVI) derived from NOAA/AVHRR, the distribution of net primary productivity (NPP) over China was simulated, and thereby, for the first time, the amount and distribution of the newly identified source in China were estimated. Secondly, with the aid of the three-dimensional atmospheric chemistry model system (MM5-CALGRID), the effects of the emissions were studied. The results show that the annual aerobic plant CH4 emissions over China amount to 11.83 Tg, i.e. nearly 24% of Chinese total CH₄ emissions. And the major fraction (about 43%) comes from forests. When those emissions are considered in modeling, computed countrywide mean surface concentration of CH₄ is 29.9% higher than without them, with a maximum increase of 69.61 μg·m⁻³ in the south of Yunnan Province. In conclusion, to study CH₄ emissions from terrestrial plants over China may have important implications for correctly estimating the contribution of China to global CH₄ budget, and may call for a reconsideration of the role of CH₄ in global and regional environment and climate change. Supported by National High-Tech Research & Development Program of China (Grant No. 2006AA06A307), National Basic Research Program of China (Grant Nos. 2006CB403706 and 2006CB403703), and the Program for New Century Excellent Talents in University, and Nanjing University Talent Development Foundation     

ENSO ensemble prediction: Initial error perturbations vs. model error perturbations

Based on our developed ENSO （El Nino-Southern Oscillation） ensemble prediction system （EPS）, the impacts of stochastic initial-error and model-error perturbations on ENSO ensemble predictions are examined and discussed by performing four sets of 14-a retrospective forecast experiments in both a deterministic and probabilistic sense, These forecast schemes are differentiated by whether they con- sidered the initial or model stochastic perturbations, The comparison results suggest that the sto- chastic model-error perturbations, which are added into the modeled physical fields to mainly represent the uncertainties of the physical model, have significant, positive impacts on improving the ensemble prediction skills during the entire 12-month forecast process, However, the stochastic initial-error perturbations have relatively small impacts on the ensemble prediction system, and its impacts are mainly focusing on the first 3-month predictions.     

农村聚落选址影响因素分析

农村聚落选址影响因素研究既是对农村聚落地理学研究内容的有益补充,也是科学确定农村聚落选址,保障居民生活和生产安全及促进社会经济持续、快速、健康发展的前提,是我国新农村建设规划的基础.文章对国内外有关农村聚落分布的影响因素进行综述,遴选出影响农村聚落选址的主要因素,并进行较为系统分析,在此基础上探讨了农村聚落选址影响因素的自然因素主导-地质构造和生态安全基础上的社会经济因素主导-自然和社会经济因素并重的动态演变过程,同时探讨了农村聚落选址综合性和主导性取向.     

浅谈施工安全生产检查

安全生产是施工企业和施工项目在进行生产经营活动中的一项必不可少的重要工作．安全文化是安全生产的五要素之一,是安全生产的根本。安全生产检查是积极发展安全文化的一个基本组成部分,建设施工安全生产的安全文化,最重要的是必须高度认识建筑安全工作的重要性、复杂性,必须加大建筑施工的安全监管力度,深入进行建筑施工安全大检查,以此来遏制事故的发生,有效地降低事故频率。     

电力系统暂态稳定域近似边界可信域

可信域是电力系统暂态稳定域近似边界的有效范围,位于稳定域边界上的特征不变流形是确定可信域的重要工具。计算特征不变流形与近似边界的偏差是确定可信域的关键步骤。该文给出一种实用的可信域计算方法。该方法定义特征不变流形上一点和穿过该点沿某一坐标方向与近似边界交点间的距离为偏差。通过WSCC 4机11节点系统和IEEE 10机39节点系统仿真,结果表明该偏差与严格意义下的偏差具有一致性,可用于提高电力系统暂态稳定近似边界可信域计算的速度。     

一种新的支持向量回归预测模型

综合最小二乘回归估计和支持向量机回归估计算法的各自在回归理论上的优势,通过理论推导,提出一种改进的支持向量机回归估计算法--SVR-LS方法.然后通过实验对比验证,发现新方法不但在拟合逼近方面有不错的效果,而且在回归估计方面,其学习速度和精度都要优于标准的支持向量机回归估计算法.     

银改性六方介孔硅的合成及其抗菌性能研究

采用溶胶凝胶法合成了银改性六方介孔硅(AgHMS)抗菌材料,以X射线衍射(XRD)、红外(FTIR)、固体紫外漫反射(UVVis)、环境扫描(ESEM)、电子能谱(EDS)、热重(TGDTA)及N2的吸附脱附技术对材料结构和特性进行了分析,通过浊度值测定法考察了材料的抗菌性能。结果表明：AgHMS具有较好的热稳定性,银在材料中以骨架和非骨架态两种形式存在并且分散均匀。银的引入会导致六方介孔硅(HMS)载体材料的结晶度、介孔有序度、比表面积及平均孔径等的变化,模板剂及脱模温度对Si-O的红外吸收峰峰位及强度也有显著影响。抗菌实验表明：银改性六方介孔材料具有优良的抗菌性能,对金黄色葡萄球菌、芽孢杆菌、大肠杆菌及枯草杆菌的抗菌性能依次增强。抗菌剂质量浓度为0.20 mg/L时对枯草杆菌的生长可起到抑制作用;当其质量浓度为1.00 mg/L,12 h后即可实现对枯草杆菌的彻底杀灭。     

石质丘陵造林辅助措施优化分析

以五角枫、火炬树为材料,运用3因素5水平二次正交旋转组合试验设计方法,研究了石质丘陵春季造林中,保水剂、ABT生根粉和基肥3项造林辅助措施对造林成活率和新植幼树生长量的综合作用。结果表明：保水剂、ABT对2个树种造林成活率的促进作用分别达到极显著和显著水平;施用基肥虽然对2个树种造林成活率有显著的不利影响,但对成活后的2个树种幼树生长量都有极显著的促进作用;保水剂、ABT生根剂对五角枫的新梢生长量有显著的促进作用,对火炬树高生长影响则不显著。综合成活率和幼树生长2个目标,经计算机模拟优化得出:保水剂的推荐用量,火炬树为36.8~39.9 g/株,五角枫为35.1~39.2 g/株;生根剂的推荐使用量,火炬树为31~53.7 mg/kg,五角枫为41.9~60.1 mg/kg;基肥则以不用为宜。     

鄂尔多斯盆地南部上三叠统延长组物源方向与沉积体系分析

运用古水流、重矿物特征研究、粒度分析、薄片骨架矿物成分分析等方法,对鄂尔多斯盆地南部上三叠统延长组的物源及源区母岩性质进行了系统研究,认为延长组存在有东北、西南、东南和西部4个方向物源.依据物源方向、沉积环境和岩石学特征,将鄂尔多斯盆地南部上三叠统延长组划分为曲流河三角洲、辫状河三角洲、湖泊和深水重力流4种沉积体系,即东北方向的富县三角洲、东南方向的庙湾-宜君-黄陵三角洲、西南方向的彬县-长武三角洲,以及正西方向的庆阳-合水三角洲.详细阐述了不同三角洲沉积体系和深水重力流沉积体系的演化过程,分析了沉积体系与油气的分布关系,认为油气主要富集在水下分流河道、河口坝及其叠合部位,以及深水区的砂质碎屑流和浊积体等能构成岩性圈闭的储集岩体内.沉积物源的研究和沉积体系演化的分析有助于油气勘探的部署.     

一类模糊控制器的设计算法及其分类

给出了由模糊蕴涵算子构造模糊控制器的一般算法.根据模糊控制器的响应函数的拟合性质将其分为4种类型:具有泛逼近性的模糊控制器、只具有拟合性的模糊控制器、只具有阶跃响应性的模糊控制器和不定型的模糊控制器.