Assessment of Future Drought Conditions in the Chesapeake Bay Watershed

Impacts of climate change on the severity and intensity of future droughts can be evaluated based on precipitation and temperature projections, multiple hydrological models, simulated hydrometeorological variables, and various drought indices. The objective of this study was to assess climate change impacts on future drought conditions and water resources in the Chesapeake Bay (CB) watershed. In this study, the Soil and Water Assessment Tool (SWAT) and the Variable Infiltration Capacity model were used to simulate a Modified Palmer Drought Severity Index (MPDSI), a Standardized Soil Moisture index (SSI), a Multivariate Standardized Drought Index (MSDI), along with Coupled Model Intercomparison Project Phase 5 (CMIP5) climate models for both historical and future periods (f1: 2020‐2049, f2: 2050‐2079). The results of the SSI suggested that there was a general increase in agricultural droughts in the entire CB watershed because of increases in surface and groundwater flow and evapotranspiration. However, MPDSI and MSDI showed an overall decrease in projected drought occurrences due to the increases in precipitation in the future. The results of this study suggest that it is crucial to use multiple modeling approaches with specific drought indices that combine the effects of both precipitation and temperature changes.     

苏南农村地区大气PM2.5元素组成特征及其来源分析

为了解苏南农村地区大气细颗粒物的污染水平及其可能的来源,在2002年7月-2003年1月的夏、秋、冬3个季节对雪堰镇和太湖站PM_2.5进行采样和分析,得到了PM_2.5和14种组成元素的质量浓度.研究表明,苏南农村地区PM_2.5的污染水平较高,S,Zn,Pb和As 4种污染元素的质量浓度水平与城市接近;组成元素的季节分布规律存在区域差异,这可能与局地源的贡献,大气细颗粒物中、长距离传输以及复杂的气象条件有关.因子分析结果表明,土壤源、燃煤源、冶金或垃圾焚烧和汽车尾气4类源对PM_2.5有明显贡献,说明人类活动对苏南农村地区PM_2.5具有重要影响.      

西部大开发中的生态安全问题

正确处理区域发展与生态安全是西部开发战略的关键。以可持续发展为目标的区域空间结构理论 ,分析了在新一轮科技革命和产业革命的新形势下推动区域发展和区域空间结构演变的决定性因素 ,以及实行效益原则与社会公平原则相统一的必要性 ,从中引出西部大开发中确保生态安全的极端重要性。并就实现区域发展与生态安全的双赢目标所必须建立的能力体系和制度体系提出了建议。      

高峰矿提升机用钢丝绳无损检测方法的研究

介绍了利用漏磁场原理检测钢丝绳断丝 ,磁桥回路测量钢丝绳磨损信号 ,并实现在一个传感器中对上述多种缺陷的综合检测。在信号处理方面 ,结合不同信号特征 ,设计了相应的电路和处理软件 ,实现了缺陷的定量检测     

Late-onset growth restriction in Galloway–Mowat syndrome: a case report

Galloway–Mowat syndrome (GMS) is a rare autosomal recessive disorder and is characterized by marked intrauterine growth retardation, central nervous system anomalies, and early onset nephrotic syndrome. Of the reported cases in the literature, all were diagnosed postnatally. We describe a case of GMS in which only late-onset intrauterine growth restriction was detected by prenatal ultrasound. In her fourth pregnancy, the mother had delivered a male baby with clinical features of GMS who died at seven months of age due to early onset of nephrotic syndrome. In her fifth pregnancy, serial ultrasound examinations were normal during the first and second trimester of pregnancy. Growth restriction and microcephaly were not detectable until 28 to 32 weeks' gestation. At 40 weeks' gestation, a female baby was born with dysmorphic features of GMS. Nephrotic syndrome developed after birth and renal biopsy revealed minimal change nephrotic syndrome. The prenatal course of this case suggests GMS may not be diagnosed in early pregnancy and the only abnormality detected before birth was intrauterine growth restriction. Copyright © 2005 John Wiley & Sons, Ltd.     

青海省近20年森林植被碳储量变化及其现状分析

基于林业生态功能和青海省森林资源清查数据,采用森林植被生物量换算因子连续函数法,系统估算与分析青海省森林植被碳储量、碳密度,研究其近20 a碳储量变化并进行现状分析。结果表明：(1)青海省森林碳储量为11 182 64222 t,占同时期全国总碳储量的198%,青海省森林生态系统中面积占较大比重的中龄林,其碳储量尚未达到最大,有较大发展空间;(2)青海省近20 a天然林类型中碳储量较大的前4种分别是：柏木（Cupressus funebris）、桦木（Betula）、杨树（Populus）、云杉（Picea asperata）天然林,表明这几种天然林在青海省森林植被中占有重要的地位,其集中分布对区域生态功能的发挥起主导作用;(3)所采用的碳储量估算方法尚存不足,在以后计算中应考虑根据不同林分类型的含碳量进行计算     

Leak detection for long transportation pipeline using a state coupling analysis of pump units

Leak detection for long transportation pipeline with a large economic and environmental impact has been an area of intensive research for more than five decades. This paper presents a novel pipeline leak detection scheme based on a state coupling analysis (SCA). Instead of monitoring the pipeline and pump units separately, SCA introduces a new detecting method of analyzing data in a coupling running condition. A novel capture method for abnormal pressure based on logical reasoning algorithm is proposed. Hamming approach degree arithmetic is applied to calculate the matching mode identifying the state of units. SCA is used to reduce the rate of false alarm and detect the leak with a high detecting sensitivity for long transportation pipeline. An on-line software system based on SCA is utilized to achieve superior accuracy and implementation. An industrial case study for coupling system pipeline leak detection is used as an example to validate the effectiveness of the proposed method.     

软件密集型装备备件保障优化方法研究

在软件密集型装备备件保障过程中,系统总体在备件保障各个环节发挥了越来越重要的作用。本文通过分析备件保障过程中的站点设置问题,研究备件保障需求中的备件补充方式,建立系统备件保障的平均概率模型,该模型为装备保障部门计算系统备件保障概率提供了一定的理论依据。     

土壤水分管理对甲烷和氧化亚氮排放的影响

为控制农田温室气体排放的途径提供依据,通过实验室培养的方法测定了不同水分管理条件下CH4和N2O的排放,干旱处理（60％-70％WFP）和长期淹水土样在施肥后的Eh变化。最终得出：稻田CH4和N2O排放之间存在着互为消长的关系（R2=0．609）,CH4和N2O的排放是水肥共同作用的结果,水分管理通过Eh来影响气体排放,有机质是造成前后期排放浓度差异的主要原因。     

Bimetallic atomic site catalysts for CO2 reduction reactions: a review

Environmental Chemistry Letters - Carbon neutral becomes one of the most important environmental goals due to the excessive emission of CO2. The reduction of CO2 into valuable chemicals or fuels is...