Designing an efficient adaptive cluster sample

The choice of neighborhood definition and critical value in adaptive cluster sampling is critical for designing an efficient survey. In designing an efficient adaptive cluster sample one should aim for a small difference between the initial and final sample size, and a small difference between the within-network and population variances. However, the two aims can be at odds with each other because small differences between initial and final sample size usually means small within-network variance. One way to help in designing an efficient survey is to think in terms of small network sizes since the network size is a function of both critical value and neighborhood definition. One should aim for networks that are small enough to ensure the final sample size is not excessively large compared with the initial sample size but large enough to ensure the within-network variance is a reasonable fraction of the population variance. In this study surveys that had networks that were two to four units in size were the most efficient.     

网络音乐作品著作权的保护的几点建议

在数字作品著作权越来越频繁受到侵犯的今天,如何对其进行有效的保护,维护著作权人的利益,给法律提出了更高的要求.因此,来阐述与著作权保护相关的几个理论问题,提出对网络音乐作品保护的几点建议,以形成一个以保护音乐作品著作权人利益为宗旨的保护体制.     

Subgrid-Scale Modeling of Reacting Scalar Fluxes in Large-Eddy Simulations of Atmospheric Boundary Layers

In large-eddy simulations of atmospheric boundary layer turbulence, the lumped coefficient in the eddy-diffusion subgrid-scale (SGS) model is known to depend on scale for the case of inert scalars. This scale dependence is predominant near the surface. In this paper, a scale-dependent dynamic SGS model for the turbulent transport of reacting scalars is implemented in large-eddy simulations of a neutral boundary layer. Since the model coefficient is computed dynamically from the dynamics of the resolved scales, the simulations are free from any parameter tuning. A set of chemical cases representative of various turbulent reacting flow regimes is examined. The reactants are involved in a first-order reaction and are injected in the atmospheric boundary layer with a constant and uniform surface flux. Emphasis is placed on studying the combined effects of resolution and chemical regime on the performance of the SGS model. Simulations with the scale-dependent dynamic model yield the expected trends of the coefficients as function of resolution, position in the flow and chemical regime, leading to resolution-independent turbulent reactant fluxes.     

环境专家系统

本文介绍了国内外环境专家系统的发展状况。环境专家系统成功的应用表明环境专家系统是解决环境问题的一个有力工具，环境专家系统将越来越广泛地应用于环境科学中，环境专家系统与决策支持系统相结合以及将神经网络技术应用于环境专家系统中，是环境专家系统的发展方向，文中还介绍了我们正在研究的大气污染总量控制规划专家系统。     

沈阳市大气颗粒物的特征

本文根据沈阳市环境监测及科学研究的有关信息，简要综述了沈阳市区大气颗粒物的污染水平、物理和化学性质及针对性的防治颗粒物污染的建议。     

滇池流域水资源调控仿真框架研究

以滇池流域为例，介绍一种利用概化网络进行水资源调控仿真与预测的思路与方法，为流域水资源的宏观调控与管理规划提供决策支持。     

抚顺市空气环境容量达标对策研究

论述了科学测算城市的空气环境容量、实施污染物总量控制、优化污染治理方案、实现环境质量达标的意义。通过对抚顺市区环境空气质量的分析得出影响抚顺市区环境空气质量达标的主要因子是TSP,其主要来源是燃煤和扬尘。由此．提出了空气质量达标的对策和具体措施。     

ADMS仿真模拟在总量控制中的应用

ADMs是新一代的大气扩散模型，用来评估空气污染扩散的问题。抚顺市2004年采取了大气污染治理措施并使用ADMs模型予以评估。仿真模拟的结果表明各项措施的效果并不和治理时的投资成比例，也不和污染物的削减总量成比例．说明治理过程中的科学性和经济性不够理想，也表明总量控制方针在实施中有许多实际问题需要解决。     

七台河市大气污染特征及变化浅析

通过对七台河市2006年1月起空气连续监测系统正式运行以来的监测数据分析,归纳、总结七台河市大气污染物随季节变化规律,每日、小时变化规律及市区不同地区大气污染物分布特征,并对这种特征及变化规律进行分析.     

化石燃料结构变化对大气中δ~(13)CO_2的影响

根据煤炭、石油和天然气等化石燃料的CO2排放量及其碳稳定同位素组成,用按比例叠加的方法逐年计算1860~1996年CO2化石燃料源的d13CO2(PDB),用简单全球碳循环模式研究该变化对大气d13CO2的影响,并将计算结果与CMDL近10年的监测数据进行对比.结果表明,化石燃料源的d13CO2在140年内下降了4.5,在碳循环模式中考虑这种动态变化之后,大气d13CO2的模拟结果与同期实测值的相关程度有较大提高.