基于BEPS生态模型对亚洲东部地区蒸散量的模拟

气候变化和人类活动的加剧导致亚洲东部地区陆地生态系统的碳水循环过程发生显著的变化,成为全球变化研究最关注的对象之一。实际蒸散(ET)是陆地生态系统碳水循环的重要组成部分,但对该地区ET特征的研究尚不够深入。论文利用遥感、气象和土壤等资料驱动生态过程模型BEPS对亚洲东部地区1982—2006年间的ET进行了模拟分析。利用6个站的通量实测数据验证表明,BEPS模型能够解释ET的81.23%的年变化和86.4%的10 d变化。模拟结果表明:亚洲东部的ET呈现出从东南向西北和西南沙漠地区逐渐减少的分布特征,最小值位于中国的西北沙漠地区;ET与降水量之比从东南和东北地区向西北内陆和西南沙漠地区逐渐增加,其中在中国长江以南的亚洲东部地区,平均值为0.4,而在沙漠地区接近1.0。在1982至2006年期间,研究区年ET总量的平均值为12 045×109m3/a,其中,中国、泛东南亚和印度的ET总量占整个研究区的62.4%;研究区的单位面积ET均值为401 mm/a,在泛东南亚地区最大(1100 mm/a),在蒙古最小(134 mm/a)。在所有的地表覆盖类型中,常绿阔叶林的ET总量和平均值都为最大,城镇地区的ET总量和平均值都为最小。研究区的ET总量呈增加趋势,草地、稀树草原、裸地和城镇的ET明显上升,其它地表覆盖类型的ET变化不明显。     

工程用Ag/AgCl参比电极性能对比研究

使用热浸涂法和粉压法制备了工程用Ag/AgCl参比电极.电化学性能测试表明热浸涂法和粉压法制备的Ag/AgCl参比电极的电位稳定性都比较好,但热浸涂法制备的Ag/AgCl参比电极的耐极化性能优于粉压法制备的Ag/AgCl参比电极.热浸涂法和粉压法制备的Ag/AgCl参比电极的温度系数都比较小,温度响应特性较好.海水流速...     

Temporal Changes in Streamflow and Attribution of Changes to Climate and Landuse in Wisconsin Watersheds

Previous historic trends analyses on 21st Century hydrologic data in the United States generally focus on annual flow statistics and have continued to use USGS hydro‐climatic data network (HCDN) stations, although post‐1988 diversions and runoff regulations are not reflected in the HCDN. Using a more recent dataset, Geospatial Attributes of Gages for Evaluating Streamflow, version II (GAGES II), compiled by Falcone (2012), which includes more watersheds with reference conditions, a comprehensive analysis of changes in seasonal, and annual streamflow in Wisconsin watersheds is demonstrated. Given the pronounced influence of seasonal hydrology in Wisconsin watersheds, the objective of this study is to elucidate the nature of temporal (annual, seasonal, and monthly) changes in runoff. Considerable temporal and regional variability was found in annual and seasonal streamflow changes between the two historic periods 1951‐1980 and 1981‐2010 considered in the study. For example, the northern watersheds show relatively small changes in streamflow discharge ranging from ?6.0 to 4.2%, while the southern watersheds show relatively large increases in streamflow discharge ranging from 13.1 to 18.2%. To apportion streamflow changes to climate and nonclimatic factors, a method based on potential evapotranspiration changes is demonstrated. Results show that nonclimatic factors account for more than 60% of changes in annual runoff in Wisconsin watersheds considered in the study.     

基于遥感的千烟洲人工林蒸散及其组分模拟研究

论文通过改进遥感蒸散模型的关键参数,结合遥感数据和气象观测数据,对2003—2008年江西千烟洲人工林生态系统蒸散及其组分进行模拟,并利用涡度相关技术获取的蒸散实测数据对模型模拟结果进行验证和评价。结果表明:①年均蒸散总量模拟值比实测值偏低2.4%,决定系数与均方根误差分别为0.83和0.61 mm·d^-1。②土壤蒸发、林冠截留蒸发和植被蒸腾分别占总蒸散量的12%、23%和65%。其中,土壤蒸发季节及年际变化相对稳定;林冠截留蒸发季节变化明显且在不同年份差异较大;植被蒸腾季节变化明显,但年际变异较小。③1—3月植被光合作用较弱,植被蒸腾与蒸散比小于30%。随着植被蒸腾的增强,从4月开始植被蒸腾与蒸散比迅速增加,在生长旺季(7月底)可达到约90%。由于该模型所需数据在区域尺度较易获取,从而为开展区域尺度中亚热带人工林生态系统蒸散及其组分模拟提供方法支撑。     

高海拔环境下离心风机性能数值模拟研究*

为研究高海拔环境下离心风机的运行性能规律,采用计算流体力学（CFD）方法对海拔高度分别为0,1 000,2 000,3 000,4 000和5 000 m条件下的离心风机流场及性能进行三维数值模拟。研究结果表明:相同工况风量条件下,风机内部流场形态不受海拔高度影响,但随着海拔的升高,内流场各处压力绝对值均减小,风机叶片载荷减小,风机蜗壳出口压力及轴功率均大致呈线性趋势降低,海拔每升高1 000 m,风机输出全压及静压分别降低9.3%及9.1%左右,轴功率降低9.0%左右。离心风机效率受海拔高度影响较小,模拟结果表明,各工况条件下,海拔每升高1 000 m,风机全压及静压效率分别平均降低0.21%和0.29%左右。研究为保证高海拔地区离心风机的高效运转及风机选型提供理论参考。     

环境标准物质探讨及含有干扰组分的COD标准物质的研制

很多标准物质与环境实际样品在基体组成上存在着很大差异．因此在环境监测中仅仅使用基体纯净的标准物质不能完全有效地进行质量控制,根据上述问题,本文介绍了含有干扰组分的COD标准物质的研制与应用。      

Factors affecting the quantitative uncertainty of the estimated short-term intake. Part II—Practical examples

ABSTRACT

The effects of the spread of residue concentrations in the samples derived from the selected supervised trials and the number of trials were studied on the magnitude and uncertainty of the short-term dietary intakes calculated with the proposed new procedure (IESTI_p) and that one used currently by the FAO (Food and Agriculture Organization) and WHO (World Health Organization) Joint meeting on Pesticide Residues (JMPR) (IESTI_c). The residue data of 10 pesticides were obtained from supervised trials conducted on apples and pears. The methods described in Part I were used for the calculations of the uncertainty. The results indicate that the ratio of IESTI_P to IESTI_c (φ_IESTI) is directly proportional to the ratio of the estimated maximum residue level (MRL), recommended by the JMPR; to the highest residue (HR) observed in supervised trials, and it may have a wide range depending on the particular conditions. The φ_IESTI becomes greater with the increase of the difference between the mrl or maximum residue limit (MRL, established by the Codex Alimentarius Commission, CAC) and HR, and becomes smaller if the difference between the large portion (LP) and unit mass (U) decreases. The φ_IESTI ranged between 2 and 5.1 in the 16 cases examined indicating that the IESTI_p calculation method leads to higher intake estimates. The ratio of CV_IESTIp and CV_IESTIc ranged typically between 0.62 and 1.71. It rapidly increased up to 12 trials. For a larger number of trials, the ratio remained practically constant (1.69–1.71). The processing factor (PF) equally affects the MRL and HR values, therefore, it will not practically influence the φ_IESTI. The uncertainty of the estimated median residues depends on the spread and number of values in the residue datasets, which affects the uncertainty of the conversion factor (CF) and subsequently the uncertainty of the estimated IESTI_p. Residue values obtained from minimum nine independent trials are required for the correct calculation of the 95% confidence intervals of the calculated median residues. The uncertainty of the analytical results directly affects the median, HR values and indirectly the calculated mrl and the MRL derived from it. Therefore, it should also be considered for the calculation of the combined uncertainty of the conversion factors. For the correct interpretation of the results of dietary exposure calculations, the upper 95% confidence limit of the short-term intake should also be considered. However, it is not the current practice of regulatory agencies or JMPR.     

Evaluating the impact of green roof evapotranspiration on annual building energy performance

The performance of the building envelope predominantly determines the ultimate energy performance throughout the lifecycle of a building. A sustainable alternative to enhance roof performance while limiting heat flux through a roof is integrating passive techniques such as green roof. Particularly, green roof performance is sensitive to local climate. The main objective of this study was to evaluate the evapotranspiration effect of an extensive green roof on annual energy consumption of an office building in relation to the humid continental climate of Republic of Korea. The dynamic behavior of green roof and building energy performance were investigated through a parametric simulation method using green roof module in EnergyPlus coupled with jEPlus. Structural data of the reference building and ASHARE 90.1-2007 operational schedules were used as inputs for baseline building model while inputs for the green roof module were based on experimental data sets. Due to the influence of the humid conditions and local wind current on the evapotranspiration process, it was generally found that high leaf area index (LAI) reduced cooling energy demand and somewhat reduced heating energy demand as well; corresponding to the highest daily evapotranspiration fluxes of 4.79 mm day^?1 in summer and 1.80 mm day^?1 in winter. Increasing LAI from 20% to 100% cover increased evapotranspiration flux by 10.4% in summer and 80.2% in winter. Thus to minimize energy losses in winter, foliage cover must be carefully considered. Within limitations specified, the overall annual building energy consumption deceased by 90.9 GJ (3.7%).     

海洋石油污染监测(艹屈)标准物质的研制

介绍了[艹屈]标准物质的研究、制备方法,进行了均匀性检验、稳定性检验,统计计算了检验结果。结果表明,该标准物质的均匀性和稳定性良好,在5a内有效,标准物质符合国家标准,可用于海洋环境监测。     

对美军装备采购合同管理的分析与借鉴

装备采购合同管理是装备采购管理的重要组成部分,是军方依法执行合同、实现合同权利的主要手段。对美军装备合同管理进行分析,进而提出若干有益于我军装备采购合同管理的借鉴意见。