中国北方地区沙尘暴变化趋势初探

沙尘暴是一种重要的环境问题和自然灾害，是土地沙漠化程度的重要指标。本文利用１９５１～１９８０年的整编气候资料、１９８１～１９８７年中国地面气象记录月报资料和１９９３～１９９４年的两个沙尘暴个例资料，对我国北方地区沙尘暴的空间分布和时间变化及其成因作了初步探讨，并对未来的变化趋势进行了初步预测。结果表明：沙尘暴主要发生在我国西北地区，且有两个多发中心区，即塔无拉玛干沙漠的西南部和甘肃河西走廊东部。沙尘暴主要发生在春季，尤以四月份最多；沙尘暴的形成是地形、地表沙尘物质、有利的急浪位置、低层大气的不稳定和锋面过境后的大风五种基本因素相互作用的结果；就整个北方地区而言，１９５１～１９８７年沙尘暴出现日数总的趋势是波动式减少的，但不同干旱气候区略有差异；本世纪末到下世纪中叶，整个北方地区沙尘暴总的趋势将呈波动式增加（约比１９５１～１９８７年的平均值增加７％）。     

Application of continuous time random walk theory to nonequilibrium transport in soil

Continuous time random walk (CTRW) formulations have been demonstrated to provide a general and effective approach that quantifies the behavior of solute transport in heterogeneous media in field, laboratory, and numerical experiments. In this paper we first apply the CTRW approach to describe the sorbing solute transport in soils under chemical (or) and physical nonequilibrium conditions by curve-fitting. Results show that the theoretical solutions are in a good agreement with the experimental measurements. In case that CTRW parameters cannot be determined directly or easily, an alternative method is then proposed for estimating such parameters independently of the breakthrough curve data to be simulated. We conduct numerical experiments with artificial data sets generated by the HYDRUS-1D model for a wide range of pore water velocities (υ) and retardation factors (R) to investigate the relationship between CTRW parameters for a sorbing solute and these two quantities (υ, R) that can be directly measured in independent experiments. A series of best-fitting regression equations are then developed from the artificial data sets, which can be easily used as an estimation or prediction model to assess the transport of sorbing solutes under steady flow conditions through soil. Several literature data sets of pesticides are used to validate these relationships. The results show reasonable performance in most cases, thus indicating that our method could provide an alternative way to effectively predict sorbing solute transport in soils. While the regression relationships presented are obtained under certain flow and sorption conditions, the methodology of our study is general and may be extended to predict solute transport in soils under different flow and sorption conditions.     

厦门市空气质量臭氧预报和评估系统

为了评价和预测厦门市区空气中臭氧的污染水平,运用2006～2009年的监测数据对臭氧的污染成因及其变化规律进行研究。通过风向、风速、气温、湿度等气象因子对臭氧浓度影响的分析,进而运用多元线性回归法建立厦门市臭氧预报及评估系统。     

220 kV高压输电线电磁辐射水平及防护距离预测

依据<500 kV超高压送变电工程电磁辐射环境影响评价技术规范>(HJ/T 24-1998)中的预测模式对监测点周围地面1.5 m处工频电场进行了验证性监测,表明实际测定结果与理论计算结果基本吻合.通过对220 kV双回同相、双回逆相和单回线路下地面1.5 m、4.5 m、和7.5 m处工频电场变化趋势分析,预测了220 kV高压输电线产生的电磁辐射水平,以及不同房屋结构的防护距离.提出了220 kV高压输电线电磁辐射的防护措施.     

Study of fuel oxygenates solubility in aqueous media as a function of temperature and tert-butyl alcohol concentration

Methyl tert-butyl ether (MTBE) is the most widely used oxygenate in gasoline blending and has become one of the world’s most widespread groundwater and surface water pollutants. Alternative oxygenates to MTBE, namely ethyl tert-butyl ether (ETBE), tert-amyl ether (TAME) and diisopropyl ether (DIPE) have been hardly studied yet. The solubility of these chemicals is a key thermodynamic information for the assessment of the fate and transport of these pollutants. This work reports experimental data of water solubility at the range from 278.15 to 313.15 K and atmospheric pressure of ethers used in fuels (MTBE, ETBE, TAME and DIPE) due to the strong influence of temperature on its trend. From the experimental data, temperature dependent polynomials were fitted, thermodynamic parameters were calculated and theoretical models were used for prediction. Finally, the tert-butyl alcohol (TBA) influence in the solubility of MTBE and ETBE in aqueous media was studied.     

地下商业街建筑人员疏散预测

利用网络控制原理地下商业街建筑人员疏散行为进行模拟,建立疏散预测模型,通过计算机软件的开发预测建筑人员疏散所需时间动态模拟疏散过程。并根据预测结果对建筑方案及疏散计划方案加以修改完善,以保证建筑中所有人员在火灾发生时得以安全疏散。     

用灰色建模法预测矿井瓦斯涌出量

在分析了传统的矿井瓦斯涌出量预测方法的基础上 ,应用灰色系统理论 GM(1,1)模型 ,对矿井瓦斯涌出量进行预测 ,并在实际中得到了较好的验证。     

Logistic回归模型在尘肺发病预测与控制中的应用研究

目的 :探讨 L ogistic回归模型在尘肺发病预测与控制中的应用。方法 :采用多元Logistic回归统计方法建立粉尘作业工人的接尘工龄 (ET)、工龄平均浓度 (AEC)、粉尘毒性 (T)三因素与尘肺发病概率的回归模型。结果 :尘肺发病预测与控制的回归模型为 :P=1/ { 1+ exp[- (- 5.4 70 7+ 0 .0 94 7ET+ 0 .0 0 2 4 AEC+ 1.9784 T) ]} ,接尘工龄等三因素对尘肺发病影响的比数比分别为 :1.0 994 (ET)、1.0 0 2 4 (AEC)和 7.2 310 (T)。结论 :所建立尘肺发病预测与控制的回归模型与所研究人群的符合率较高 ,对今后预防尘肺发生的科学化管理与决策有较好的实用性和应用价值。     

Importance of insects in environmental impact assessment

Insects are particularly suited for use in environmental impact assessment (e.i.a.) because of their high species diversity, ubiquitous occurrence, and importance in the functioning of natural ecosystems. Examples are given of the use of insects in the predictive phase of e.i.a., in the monitoring and assessment phase, and in the much rarer instance of an e.i.a. that includes both of these phases. The importance of working at the species level to understanding the results of e.i.a. is emphasized.