An inexact optimization approach for river water-quality management

A previously developed fuzzy waste load allocation model (FWLAM) for a river system is extended to address uncertainty involved in fixing the membership functions for the fuzzy goals of the pollution control agency (PCA) and the dischargers using the concept of grey systems. The model provides flexibility for the PCA and the dischargers to specify their goals independently, as the parameters for membership functions are considered as interval grey numbers instead of deterministic real numbers. An inexact or a grey fuzzy optimization model is developed in a multiobjective framework, to maximize the width of the interval valued fractional removal levels for providing latitude in decision-making and to minimize the width of the goal fulfillment level for reducing the system uncertainty. The concept of an acceptability index for order relation between two partially or fully overlapping intervals is used to get a deterministic equivalent of the grey fuzzy optimization model developed. The improvement of the optimal solutions over a previously developed grey fuzzy waste load allocation model (GFWLAM) is shown through an application to a hypothetical river system. The fuzzy multiobjective optimization and fuzzy goal programming techniques are used to solve the deterministic equivalent of the GFWLAM.     

陶瓷厂喷雾干燥塔白烟形成的机理及解决措施

针对陶瓷厂烟囱冒“白烟”,造成环境污染的现象,提出了“降温法”和“升温法”两种治理方案,并对“升温法”方案建立了数学模型,通过数值求解,得到需要升高的最小临界温度值。计算结果已用于陶瓷厂烟气治理中,验证了其正确性。     

全国辐射环境监测网络射频综合场强测量比对

在2011年全国辐射环境监测网络射频综合场强项目测量比对中,采用稳健统计方法对36家参比单位的78个比对测量结果进行统计分析。结果表明,全国各监测机构满意结果占87.3%,有问题结果占7.7%,离群结果占5%。对可能影响监测结果的若干因素进行了研究,如仪器型号等,反映了目前全国辐射环境监测网络射频电磁场测量项目的监测能力水平,为进一步开展质保工作提供了科学依据。     

重点污染行业环境统计准专家系统制作

以燃煤发电行业废气污染核算为例,介绍了环境统计准专家系统的制作原理。将环境统计专家的专业知识优势与先进的计算机技术结合,制作准专家系统辅助基层环境统计人员工作,可以提高环境统计数据质量。目前我国基层环境统计部门非常需要这种易用、相对准确的方式来辅助其工作,环境统计准专家系统为在当前我国国情下提高环境统计数据质量探索了一条低成本、易推广的道路。     

应用稳健统计方法对环境空气臭氧自动监测现场比对核查结果的分析研究

根据2015年9个城市53台现场臭氧分析仪的现场比对核查结果,比较研究了稳健统计方法和一般统计方法在评价国控网臭氧自动监测数据准确性和精密性上的应用。研究表明:稳健统计能够在不剔除异常数据的前提下降低异常值对正确评价臭氧自动监测数据质量的影响,适合评价现场比对核查结果;采用Hubers方法进行稳健统计,2015年国控网臭氧日常浓度点相对偏差的95%置信区间约为-0.1%至4.5%,95%预测区间为-14.0%~18.3%,变异系数约为9.5%,数据质量仍有提升空间。     

How does the spatial structure of habitat loss affect the eco-epidemic dynamics?

Habitat loss is considered as one of the primary causes of species extinction, especially for a species that also suffers from an epidemic disease. Little attention has been paid to the combined effect of habitat loss and epidemic transmission on the species spatiotemporal dynamics. Here, a spatial model of the parasite–host/prey–predator eco-epidemiological system with habitat loss was studied. Habitat patches in the model, instead of undergoing a random loss, were spatially clustered by different degrees. Not only the quantity of habitat loss but also its clustering degree was shown to affect the equilibrium of the system. The infection rate and the probability of successful predation were keys to determine the spatial patterns of species. The epidemic disease is more likely to break out if only a small amount of suitable patches were lost. Counter-intuitively, infected preys are more sensitive to habitat loss than predators if the lost patches are highly clustered. This result is new to eco-epidemiology and implies a possibility of using spatial arrangement of suitable (or unsuitable) patches to control the spread of epidemics in the ecological system.     

A derivation of the statistical characteristics of forest fires

The analysis of large data sets concerning fires in various forested areas of the world has pointed out that burned areas can often be described by different power-law distributions for small, medium and large fires and that a scaling law for the time intervals separating successive fires is fulfilled. The attempts of deriving such statistical laws from purely theoretical arguments have not been fully successful so far, most likely because important physical and/or biological factors controlling forest fires were not taken into account. By contrast, the two-layer spatially extended forest model we propose in this paper encapsulates the main characteristics of vegetational growth and fire ignition and propagation, and supports the empirically discovered statistical laws. Since the model is fully deterministic and spatially homogeneous, the emergence of the power and scaling laws does not seem to necessarily require meteorological randomness and geophysical heterogeneity, although these factors certainly amplify the chaoticity of the fires. Moreover, the analysis suggests that the existence of different power-laws for fires of various scale might be due to the two-layer structure of the forest which allows the formation of different kinds of fires, i.e. surface, crown, and mixed fires.     

Outlier detection in phosphorus dry deposition rates measured in South Florida

Dry atmospheric deposition contributes a significant amount of phosphorus to the Everglades of South Florida. Measurement of this deposition is problematic, because samples often are contaminated to varying degrees by bird droppings and other foreign materials. This study attempted to detect and remove the outliers in phosphorus (P) flux rates measured from dry deposition samples. Visual inspection of the samples, recorded in field notes, found that 30.1% of the samples contained animal droppings and frogs. Some of the samples with droppings and frogs (2.3%) had P values greater than 884 μg P m⁻² d⁻¹ (a value twice the standard deviation of the raw data mean), and were removed from further analysis. Outlier detection statistics based on a linear regression were then used for additional data screening. Eight stations in the network of 19 were removed because high contamination precluded the use of the regression model. Of the remaining samples, 15.7% were identified through the regression procedure as contaminated and were removed. The 11 station mean for P dry deposition was 85.8±79.0 μg P m⁻² d⁻¹, prior to the regression analysis, and 74.8±75.1 μg P m⁻² d⁻¹ after removal.     

高锰酸钾预氧化后地表水中三氯甲烷生成量的预测模型研究

在饮用水处理中,适当地采用高锰钾预氧化可以降低水中的三氯甲烷生成量。本文研究了影响三氯甲烷生成量的因素,如反应时间,反应温度等,并以这些影响因素为参数通过一元线性回归等数学方法,建立了各影响因素下三氯甲烷生成量折了模型和综合预测模型。     

一级动力学反应方程参数估计中若干问题的讨论

在农药的环境行为研究中,常用一级动力学反应方程来模拟农药的降解或残留。本文论述了用线性回归分析法估计一级化学动力学方程参数时存在的初始浓度飘移和非本义最优化问题,讨论了与此相关联的试验设置、安全间隔期、分段模拟和试验数据处理等问题,提出了解决问题的初步设想。