环巢湖典型农业区土壤重金属来源解析

重金属来源解析是防止或减少土壤重金属污染的必要前提。为此,采集并分析了环巢湖典型农业区408个表层土壤样品中As、Cd、Cr、Cu、Ni、Pb、Zn等7种重金属元素含量。地积累指数评价结果表明土壤重金属污染总体处于0~1级。综合相关性分析、主成分分析和聚类分析结果可知:(1)Cd、Cu、Pb、Zn主要来源于大气沉降、畜禽粪肥和化肥等人类活动;(2)成土母质是Cr和Ni的主要来源;(3)As有人类活动和成土母质双重来源。用绝对主成分得分-多元线性回归模型(APCS-MLR)对土壤中重金属来源进行了定量解析,解析结果与主成分分析和聚类分析结果相符。可见,多元统计分析结合APCS-MLR模型能很好地应用于土壤重金属来源解析。     

基于航班运行规律的典型机场NOx浓度临近预测方法研究

针对天津机场区域考虑航班运行影响,应用广义加性模型（Generalized Additive Model,GAM）建立污染物浓度预测模型,对因子间的共线性问题和交互作用进行改进,得到最优的NO_x浓度预测模型.选取天津机场区域2019年11月—2020年3月环境、气象及航班数据,建立改进的GAM.结果显示：（1）改进的GAM预测效果优,可以更加准确地预测浓度峰值及变化趋势;（2）样本量会影响模型选择的因子数量及模型性能;（3）改进模型adj-R²为0.940,实测和预测NO_x浓度的相关系数为0.975,预测效果好;（4）航班活动对机场区域污染物浓度影响较大.改进的GAM考虑污染物浓度与影响因子之间的复杂非线性关系及影响因子之间交互作用对污染物浓度变化的影响,使模型精度进一步提升. GAM对污染物浓度的准确预测可为机场区域污染防治提供依据.     

生态全息论对发展循环经济的启示

作者根据生态全息的理论，提出了推行工业生态系统和循环经济的具体步骤。发展循环经济是一个大的系统工程，涉及到经济、环境、社会的各个层面，涉及到国民经济的各个行业和企业，必须进行系统的研究和战略部署，理念不能作为目标，没有政府的支持和企业的积极参与是不行的。     

Effect of sediment properties on the sorption of C12-2-LAS in marine and estuarine sediments

Linear alkylbenzene sulfonates (LAS) are anionic high production volume surfactants used in the manufacture of cleaning products. Here, we have studied the effect of the characteristics of marine and estuarine sediments on the sorption of LAS. Sorption experiments were performed with single sediment materials (pure clays and sea sand), with sediments treated to reduce their organic carbon content, and with field marine and estuarine sediments. C₁₂-2-LAS was used as a model compound. Sorption to the clays montmorillonite and kaolinite resulted in non-linear isotherms very similar for both clays. When reducing the organic content, sorption coefficients decreased proportionally to the fraction removed in fine grain sediments but this was not the case for the sandy sediment. The correlation of the sediment characteristics with the sorption coefficients at different surfactant concentrations showed that at concentrations below 10 μg C₁₂-2-LAS/L, the clay content correlated better with sorption, while the organic fraction became more significant at higher concentrations.     

Numerical Analysis of Heat Transfer and Gas Flow in PEM Fuel Cell Ducts by a Generalized Extended Darcy Model

Abstract

In this work, gas flow and heat transfer have been numerically investigated and analyzed for both cathode/anode ducts of proton exchange membrane (PEM) fuel cells. The simulation is conducted by solving a set of conservation equations for the whole domain consisting of a porous medium, solid structure, and flow duct. A generalized extended Darcy model is employed to investigate the flow inside the porous layer. This model accounts for the boundary-layer development, shear stress, and microscopic inertial force as well. Effects of inertial coefficient, together with permeability, effective thermal conductivity, and thickness of the porous layer on gas flow and heat transfer are investigated.     

Inventing the future: scenarios, imagination, mastery and control

The complexity of mixed social, behavioral, and natural systems—such as those encountered while analyzing, understanding, and trying to manage aspects of climate change and sustainability, requires more common theoretical frameworks and technical tools than either can bear. How does human activity relate to greenhouse gas emissions, changes in the atmosphere, climate variability, and multiple impacts, outcomes, and effects? Some of the connections can be observed and measured, many cannot. Uncertainties of every conceivable sort can occur. As the time frame into the future extends, uncertainties essentially dominate conventional theories, tools, experiences, habits, processes, and so forth. The scientific consensus linking human activity to climate change is now all but settled according to The Fourth Assessment Report of the Intergovernmental Panel on Climate Change. The consensus says little, however, about who should be doing what and for what reasons under this singular, even unique circumstance. There are no data about the future on which to rely. We are challenged to imagine many different and possible “futures” as humankind seeks to exert its mastery and control. This essay considers and then weaves together several basic issues, ideas, and topics: complexity, the concept of human intentionality, several means used to exert control in organizations and social systems, and different methods being used to imagine, invent, and communicate the future.     

Analysis of 3-D Urban Databases with Respect to Pollution Dispersion for a Number of European and American Cities

Dispersion models require as input various geometrical parameters to calculate the flow field and dispersion characteristics in the urban environment. As a result of recent advances in digital photogrammetry and remote sensing, databases of the actual 3-D geometry of city centre areas are now increasingly available. In this work we outline a procedure to reduce this large amount of data to a structured input for urban pollution dispersion models, i.e. to extract the important flow and dispersion parameters from the urban databases. Based on a review of the scientific literature, we have identified a number of parameters relevant to the modelling of pollution dispersion and atmospheric flows in urban areas. These parameters are: the plan and frontal area densities, the plan and frontal area density as a function of height, the distribution of heights, their standard deviation, the aerodynamic roughness length and the sky view factor.These parameters are obtained by analysing urban Digital Elevation Models (DEMs) which are regularly spaced grids of elevation values. Examples of the parameters calculated from high-resolution databases (with pixel size of about 1 m) for three European (London, Toulouse and Berlin) and two North American (Salt Lake City and Los Angeles) cities are presented and discussed. The calculated aerodynamic roughness length was smaller for the European cities than for the North American ones. A multiplicative correction factor to the aerodynamic roughness length is proposed to include the effect of the variability of the building heights.     

A cost analysis technique for research management and design

A classic research approach is to optimize experimental design and available resources. However, that approach does not guarantee that results will be useful. This article takes the view that research should not be undertaken unless there is assurance that final results will be significant to a level specified before any work is begun. Given that assurance, the relationship between cost and statistical significance is explored, a new approach to optimization s developed, and the use of models in research design is considered.     

建筑设计的安全系统工程初探

建筑设计的任务是全面贯彻安全、适用、经济、美观的方针,高质量、高效率、高可靠地创造具有综合效益的现代环境。以当代世界安全科学的观点,中国建筑要充分地利用资金、资源、环境、土地外,更应关注与设计变量相关的“故障——风险——灾害”的背景及设计原则。本文以建筑工程设计的系统观点,总结多年来诸项建筑子系统的安全对策[6][7][8][9][16]等;探讨安全设计系统工程方法的框架体系;试图扩展可靠性工程、运筹学及新近发展的失误控制论等安全技术。     

PLANNING AND SELECTING MULTIOBJECTIVE PROJECTS BY GOAL PROGRAMMING1

ABSTRACT. A multiple goal planning approach is proposed as a solution to the public water resources project selection problem. The goal programming technique enables a comprehensive water resources model. The model considers both economic and environmental objectives and may be implemented with data which are available to project planners.