电除尘器及其电离荷电机制的研究新进展

详细介绍了电除尘技术研究现状、现存问题及其研究趋势.目前电除尘技术的理论尚不完备,属于经验工程的学科,电除尘器的技术性能优劣取决于设计命中率.为此,论述烟尘荷电凝聚机制并研究电离放电通道中的带电粒子复合问题及其输运特性等,以便解决除尘电场中的电离占空比、输运项甚低等问题;研究了烟尘荷电、凝聚的物理过程,以便进一步提高电除尘器的性能.     

Monitoring Long-term Trends in Sulfate and Ammonium in US Precipitation: Results from the National Atmospheric Deposition Program/National Trends Network

Data from the National Atmospheric Deposition Program/National Trends Network (NADP/NTN) indicate significant changes have occurred in precipitation chemistry and the chemical climate in the United States (US). A Seasonal Kendall Trend (SKT) analysis shows statistically significant increases in precipitation ammonium concentrations at 64% of 159 continental US NADP/NTN sites evaluated from Winter 1985 to Fall 2004 (Dec. 1984 – Nov. 2004). Sulfate decreases were widespread, with an SKT analysis indicating statistically significant decreases at 89% of sites evaluated. Ratios of chemical equivalent concentrations of ammonium to sulfate in precipitation have risen to the extent that ammonium now exceeds sulfate over more than half of the continental U.S. on a precipitation-weighted-mean annual basis. These trends in the concentrations of ammonium, sulfate, and other species have been accompanied by significant decreases in the frequency of acidic precipitation (pH < 5.0) in the last decade.     

浙江泥石流气象特征分析

利用浙江泥石流的个例资料及气象资料,分析了浙江泥石流发生的气象特征.重点分析了触发泥石流的降水及天气形势特征,包括灾害发生前10天及当天的降水特征,强降水与泥石流发生时间、发生规模的关系,泥石流发生的不同环流背景和影响系统等.     

WATER SHORTAGES,DEVELOPMENT, AND DROUGHT IN ROCKLAND COUNTY,NEW YORK1

Knowledge of the historical variability of regional climate is an essential element of successful water resource planning. Lacking such perspective, planners and managers can be deceived as to the severity of a recent climate extreme, such as drought, and place a disproportionate blame on the climate, not the integrity of the supply system should water restrictions become necessary to avoid shortages. Presented here is a vivid example of how development, a lack of adequate planning, and climate variability have converged to produce three water emergencies in Rockland County, New York, since 1995. An examination of climate data over the past century indicates that the severity of the recent droughts was well within the range of past variability. Rather than climate alone, the recent water emergencies have highlighted a significant mismatch between supply and demand that has been developing in Rockland County over the past three decades. Substantial development, largely in the form of single‐family homes, has not been matched with a corresponding enhancement of the county's water system. Realistic plans for meeting current water demand will require cooperation among all stakeholders, beginning with an acknowledgement that climate variations are inevitable, not the sole source of blame when water shortages arise.     

柑橘皮中果胶提取条件的研究

利用酸性水解乙醇沉淀法提取果胶,分别测定了不同的浸泡时间、酸碱度及水解温度对果胶产率的影响.结果表明:浸泡时间与水解时间过长或过短,酸碱度及水解温度过高或过低,果胶的产率均不高,只有浸泡时间在2h左右、水解时间在2～2.5h、pH在2～3之间、水解温度在80～95℃时果胶的得率最大.     

对2003年春季陕西省沙尘暴、扬沙天气的分析

通过对2003年春季天气气候背景和天气气候变化的研究,指出2003年春季陕西沙尘暴、扬沙明显减少是由高空纬向环流偏强、径向环流偏弱和前期降水偏多共同所致.     

一种度量区域旱涝灾害严重性的指标

提出以洛仑兹曲线和基尼系数作为度量降水量空间分布不均匀程度的指标,来表示区域性旱涝程度.对我国区域多年逐日降水量计算的结果表明,它确实可用来做为评价区域性旱涝程度的一种新指标.     

SIMULATING THE EFFECTS OF REDUCED PRECIPITATION ON GROUND WATER AND STREAMFLOW IN THE NEBRASKA SAND HILLS1

ABSTRACT: The Nebraska Sand Hills have a unique hydrologic system with very little runoff and thick aquifers that constantly supply water to rivers, lakes, and wetlands. A ground water flow model was developed to determine the interactions between ground water and streamflow and to simulate the changes in ground water systems by reduced precipitation. The numerical modeling method includes a water balance model for the vadose zone and MOD‐FLOW for the saturated zone. The modeling results indicated that, between 1979 and 1990, 13 percent of the annual precipitation recharged to the aquifer and annual ground water loss by evapotranspiration (ET) was only about one‐fourth of this recharge. Ground water discharge to rivers accounts for about 96 percent of the streamflow in the Dismal and Middle Loup rivers. When precipitation decreased by half the average amount of the 1979 to 1990 period, the average decline of water table over the study area was 0.89 m, and the streamflow was about 87 percent of the present rate. This decline of the water table results in significant reductions in ET directly from ground water and so a significant portion of the streamflow is maintained by capture of the salvaged ET.     

华北地区干旱指数的确定及其应用

利用标准化降水指数建立了华北地区于旱指数计算公式，并对华北地区1997年的干旱和历年于温期进行了计算和分析，取得了较好的结果，试验表明该指数能运用于干旱监测业务。