The study and application of a novel hybrid system for air quality early-warning

Air quality early-warning plays a vital role in improving air quality and human health, especially multi-step ahead air quality early-warning, which is significant for both citizens and environmental protection departments. However, most previous studies have only employed simple data decomposition to perform one-step forecasting and were aimed at enhancing forecasting accuracy or stability. Little research has improved these two standards simultaneously, leading to poor forecasting performance. Because of its significance, relevant research focused on multi-step ahead air quality early-warning is especially needed. Therefore, in this paper, a novel hybrid air quality early-warning system, which consists of four modules: data preprocessing module, optimization module, forecasting module and evaluation module, is proposed to perform multi-step ahead air quality early-warning. In this system, an effective data decomposition method called the modified complete ensemble empirical mode decomposition with adaptive noise is developed to effectively extract the characteristics of air quality data and to further improve the forecasting performance. Moreover, the hybrid Elman neural network model, optimized by the multi-objective salp swarm algorithm, is successfully developed in the forecasting module and simultaneously achieves high forecasting accuracy and stability. In addition, the evaluation module is designed to conduct a reasonable and scientific evaluation for this system. Three cities in China are employed to test the effectiveness of the proposed early-warning system, and the results reveal that the proposed early-warning system has superior ability in both accuracy and stability than other benchmark models and can be used as a reliable tool for multi-step ahead air quality early-warning.     

An evolutionary system for ozone concentration forecasting

Nowadays, with more than 50 % of the world’s population living in urban areas, cities are facing important environmental challenges. Among them, air pollution has emerged as one of the most important concerns, taking into account the social costs related to the effect of polluted air. According to a report of the World Health Organization, approximately seven million people die each year from the effects of air pollution. Despite this fact, the same report suggests that cities could greatly improve their air quality through local measures by exploiting modern and efficient solutions for smart infrastructures. Ideally, this approach requires insights of how pollutant levels change over time in specific locations. To tackle this problem, we present an evolutionary system for the prediction of pollutants levels based on a recently proposed variant of genetic programming. This system is designed to predict the amount of ozone level, based on the concentration of other pollutants collected by sensors disposed in critical areas of a city. An analysis of data related to the region of Yuen Long (one of the most polluted areas of China), shows the suitability of the proposed system for addressing the problem at hand. In particular, the system is able to predict the ozone level with greater accuracy with respect to other techniques that are commonly used to tackle similar forecasting problems.     

汽车环境污染预警机制研究*

对汽车环境污染预警机制进行了研究,通过分析汽车环境污染的种类和危害提出了建立汽车环境污染预警机制的必要性。设计了预警机制的基本结构,建立了基于预警指标体系和知识表示的预警综合数据库,并且通过划分预警指标等级、设计预警规则及其知识表示建立了预警知识库,用预警推理机来协调整个预警机制。通过研制原型系统并设计预警实验,证实了提出的汽车环境污染预警机制的正确性和可行性。     

基于离群点检测和误差修正的空气质量指数预测

空气质量指数(Air Quality Index,AQI)预测可以为人们日常生产活动以及空气污染治理工作提供指导.针对空气质量指数预测模型受离群点影响较大的问题,利用孤立森林算法对空气质量数据集进行离群点分析,采用离群鲁棒极限学习机模型(ORELM)对空气质量指数进行预测,并构建误差修正模块对模型预测误差进行修正.最后...     

面向深度学习的空气质量预测研究进展

空气污染是影响公共卫生的重要因素,空气质量预测是空气污染预警的关键,是近年来环境学、统计学、计算机科学等领域中的热点研究课题.本文综述了空气质量预测方法的研究现状与进展,尤其对近年来新发展起来的深度学习方法在空气质量预测方面的应用进行了系统分析与总结.首先,介绍了空气质量预测方法的演变历程和空气污染数据集.然后,阐述了传统空气质量预测方法.随后,从时间信息、时空信息、注意力机制等角度出发,重点分析和比较了现有面向深度学习的空气质量预测方法的进展.最后,对空气质量预测方法的未来发展趋势进行了总结与展望.     

Dynamic Ensemble Multivariate Time Series Forecasting Model for PM2.5

In forecasting real time environmental factors, large data is needed to analyse the pattern behind the data values. Air pollution is a major threat towards developing countries and it is proliferating every year. Many methods in time series prediction and deep learning models to estimate the severity of air pollution. Each independent variable contributing towards pollution is necessary to analyse the trend behind the air pollution in that particular locality. This approach selects multivariate time series and coalesce a real time updatable autoregressive model to forecast Particulate matter (PM) PM2.5. To perform experimental analysis the data from the Central Pollution Control Board (CPCB) is used. Prediction is carried out for Chennai with seven locations and estimated PM’s using the weighted ensemble method. Proposed method for air pollution prediction unveiled effective and moored performance in long term prediction. Dynamic budge with high weighted k-models are used simultaneously and devising an ensemble helps to achieve stable forecasting. Computational time of ensemble decreases with parallel processing in each sub model. Weighted ensemble model shows high performance in long term prediction when compared to the traditional time series models like Vector Auto-Regression (VAR), Autoregressive Integrated with Moving Average (ARIMA), Autoregressive Moving Average with Extended terms (ARMEX). Evaluation metrics like Root Mean Square Error (RMSE), Mean Absolute Error (MAE) and the time to achieve the time series are compared.     

大气污染暴露风险防控可视化决策支持平台

针对当前我国大气污染防治正逐步由污染治理转向风险防控,而现有空气质量监测设备和平台服务仅限于环境监测而非暴露监测的问题,设计研发了一套基于B/S架构的可视化综合分析与决策支持平台——大气污染暴露风险测量系统（APERMS）。首先,基于大气污染浓度监测数据和暴露时空行为活动模式,耦合集成污染浓度制图、个体暴露测量、人群暴露测量、暴露风险评价这一完整的大气污染暴露风险测量技术路线;其次,基于高可用和可靠原则,进行系统的总体架构设计、数据库设计和功能模块设计;最终,采用GIS与J2EE Web等技术,完成APERMS开发,实现了大气污染浓度分布高时空分辨率模拟、个体和人群大气污染暴露状况精准评估、大气污染暴露风险水平全方位评价等功能。APERMS主要应用于大气污染监控和环境健康管理行业,为风险规避和污染防控提供有效的技术支持。     

基于GCN-LSTM的空气质量预测

随着我国环境监测技术的不断发展,环境空气质量的网格化监测体系越来越受到相关工作人员的青睐,为应对空气污染的网格化监测体系中的小型、微型监测站的空气质量预测问题,本文提出了一种基于GCN和LSTM的空气质量预测模型.首先利用GCN网络提取网格化监测体系中的小微型监测站之间的空间特征,然后再使用LSTM提取时间特征,最后使...     

Predicting daily ozone concentration maxima using fuzzy time series based on a two-stage linguistic partition method

Air pollution is a result of global warming, greenhouse effects, and acid rain. Especially in highly industrialization areas, air pollution has become a major environmental issue. Poor air quality has both acute and chronic effects on human health. The detrimental effects of ambient ozone on human health and the Earth’s ecosystem continue to be a national concern in Taiwan. The pollutant standard index (PSI) has been adopted to assess the degree of air pollution in Taiwan. The standardized daily air quality report provides a simple number on a scale of 0 to 500 related to the health effects of air quality levels. The report focuses on health and the current PSI subindices to reflect measured ozone (O₃) concentrations. Therefore, this study uses the O₃ attribute to evaluate air quality. In an effort to forecast daily maximum ozone concentrations, many researchers have developed daily ozone forecasting models. However, this continuing worldwide environmental problem suggests the need for more accurate models. This paper proposes two new fuzzy time series based on a two-stage linguistic partition method to predict air quality with daily maximum O₃ concentration: Stage 1, use the fuzzy time series based on the cumulative probability distribution approach (CPDA) to partition the universe of discourse into seven intervals; Stage 2, use two linguistic partition methods, the CPDA and the uniform discretion method (UDM), to repartition each interval into three subintervals. To verify the forecasting performance of the proposed methods in detail, the practical collected data is used as and evaluating dataset; five other methodologies (AR, MA, ARMA, Chen’s and Yu’s) are used as comparison models. The proposed methods both show a greatly improved performance in daily maximal ozone concentration prediction accuracy compared with the other models.     

Measurement and modelling of pollutant emissions from Hong Kong

During November 1997 a detailed airborne investigation of air pollution in the Hong Kong region was undertaken. The airborne investigation formed part of a larger study funded by the Hong Kong Environmental Protection Department (EPD) and included the development of a state of the art numerical air quality modelling system to simulate air pollution in the Hong Kong region.The system consisted of a numerical weather prediction module, a prognostic air–chemistry/transport model, an emissions inventory system and a Graphical User Interface for display of results and preparation of simulations. The purpose of the airborne investigations was to provide data on the fluxes of selected pollutants arising from or entering the Hong Kong airshed as a check on the inventory. In addition the aircraft was to provide data on other pollutants of interest particularly with respect to the formation of photochemical smog.This paper describes the inventory data obtained from the aircraft and makes comparisons between the predictions of the model and the aircraft data for one of the days when the aircraft was able to be used to estimate the total fluxes of NMHC and NO_x from the study area.     

Inferring urban air quality based on social media

Outdoor air pollution is a serious environmental problem in many developing countries; obtaining timely and accurate information about urban air quality is a first step toward air pollution control. Many developing countries however, do not have any monitoring stations and therefore the means to measure air quality. We address this problem by using social media to collect urban air quality information and propose a method for inferring urban air quality in Chinese cities based on China's largest social media platform, Sina Weibo combined with other meteorological data. Our method includes a data crawler to locate and acquire air-quality associated historical Weibo data, a procedure for extracting indicators from these Weibo and factors from meteorological data, a model to infer air quality index (AQI) of a city based on the extracted Weibo indicators supported by meteorological factors. We implemented the proposed method in case studies at Beijing, Shanghai, and Wuhan, China. The results show that based the Weibo indicators and meteorological factors we extracted, this method can infer the air quality conditions of a city within narrow margins of error. The method presented in this article can aid air quality assessment in cities with few or even no air quality monitoring stations.     

基于多元回归分析的PM2.5预测研究

PM2.5对人体健康和大气环境质量的影响众所周知,分析、预测PM2.5浓度对污染天气防治与干预有着非常重要的作用。利用灰色关联度、多元回归分析等方法对全国各大城市空气质量进行了研究,分析了影响PM2.5浓度的主要因素并进行了影响程度排序,构建了PM2.5预测模型并进行了预测实践,为我国环境空气质量预报和污染天气防治干预提供了有效的决策信息。     

基于LabVIEW的水质监测中心软件设计

针对目前我国的水质污染情况严重,水质监测手段相对落后的现状,设计了基于LabVIEW的多功能水质监测上位机软件。系统采用网络通信方式,从物联网云平台上获取数据,并结合MATLAB、Access数据库和Elman神经网络技术,分别设计出了系统概述模块、数据接收模块、水质报警模块、数据存储模块、记录查询模块和数据预测模块,完成了数据接收、存储、查询、预测等功能。测试结果表明,该系统稳定可靠,各功能模块均能正常运行,达到了软件设计标准,实现了预期的功能。     

An optimization platform for Poland's power sector considering air pollution and health effects

The article demonstrates the features and applicability of the πESA platform designed for optimization of the Poland's power sector considering air pollution and health effects. πESA is comprised of: a bottom-up energy-economic model TIMES-PL, an air quality modelling system Polyphemus and a module for assessment of environmental and health impacts MAEH. It has been designed as a web application employing computational resources of the ZEUS cluster of the PL-Grid infrastructure. The results show, that the impact of carbon prices on the fuel and technological power generation structure is much stronger as compared to impact of fuel prices. Future PM emissions from the centralized power and heat generation sector do not differ much irrespective of energy scenario considered. For analysed cases, the statistical life expectancy in Poland due to long-term exposure to PM_2.5 air pollution is reduced on average by approx. 183 days. That gives over 12 million years lost for all cohorts included in the analysis.     

基于时空相似LSTM的空气质量预测模型

由传统机器学习方法组成的空气质量预测模型得到了普遍应用,但是此类模型对于数据有效性,特别是时空相关数据的选取仍旧存在不足.针对深度学习输入数据有效性问题进行研究,提出了一种基于时空相似LSTM的预测模型(spatial-temporal similarity LSTM model,STS-LSTM),以便在时间和空间层面选取更加有效的数据.STS-LSTM分为前序、中序和后序三个模块,前序模块为时空相似选择输入模块,提出了格兰杰因果权重动态时间折叠(Granger causal index weighted dynamic time warping,GCWDTW)算法,用于选取具有更高时空相似性的数据;中序模块使用LSTM作为深度学习网络进行训练;后序模块根据目标站点特征选择不同的输出组合进行集成.STS-LSTM整体模型在空气质量预测误差上较现有算法提升了8％左右,经过有效性选取的数据对于模型精度达到了最高21％的提升.实验结果表明,对于有效数据的选取该算法取得了显著效果,将数据输入输出方法作为应用型深度学习网络的一部分,可以有效提升深度学习网络的最终效果.     

Modelling and analysis of ozone episodes

Air pollution is one of the primary environmental concerns in France due to the public health question. People wish to be informed of the air pollution level in real time or to be warned in advance of a peak of pollution.The goal of this study is to show the feasibility of developing an operational system to forecast the air pollution level. In our case, this level depends on the ozone concentration in the atmosphere.This prediction has been made by using a fuzzy logic based method. One advantage of this kind of model is to be able to extract information on the phenomena.Results obtained with this method are encouraging and some supplementary work needs to be done.     

基于机器学习的软件缺陷预测研究

基于机器学习的软件缺陷预测是一种有效的提高软件可靠性的方法。该方法基于软件模块的统计特性预测软件模块可能出现的缺陷数或是否容易出现缺陷。通过对软件模块缺陷状况的预测,软件开发组织可以将有限的资源集中于容易出现缺陷的模块,从而有效地提高软件产品的质量。基于机器学习的软件缺陷预测近年来出现了很多研究成果,文章概述该领域近年来的主要研究成果,并根据各方法的特点进行了分类。     

基于注意力机制和高斯概率估计的PM2.5浓度预测

作为衡量空气污染物浓度的重要指标, 对PM_2.5浓度进行监控预测, 能够有效地保护大气环境, 进一步地减少空气污染带来的危害. 随着空气质量自动监测站的大范围建立, 由传统的机器学习搭建的空气质量预测模型已经不能满足当今的需求. 本文提出了一种基于多头注意力机制和高斯概率估计的高斯-注意力预测模型, 并对沈阳市某监测站点的数据进行了训练和测试. 该模型考虑了PM_2.5浓度受到其他空气质量数据的影响, 将空气质量数据的分层时间戳(周、日、小时)的信息对齐作为输入, 使用多头注意力机制对于不同子空间的时间序列关联特征进行提取, 能够获得更加完善有效的特征信息, 再经过高斯似然估计得到预测结果. 通过与多种基准模型进行对比, 相较于性能较优的DeepAR, 高斯-注意力预测模型的MSE、MAE分别下降了21%、15%, 有效地提高了预测准确率, 能够较准确地预测出PM_2.5浓度.     

Accurate decision-making for timely washing of substation insulators, based on a pollution model

Substation insulators near coastal areas rapidly become polluted due to the salty wind blowing in from the sea. Hazardous levels of pollution deposit cause higher leakage currents under damp conditions, resulting in system blackouts and damage to substations due to flash-overs. This research is aimed at developing a method of reliable decision-making to determine the time at which to wash polluted insulators to avert detrimental conditions. The proposed method consists of modelling the pollution deposits, and deciding on the best time to wash the insulators by using the actual data related to pollution deposits and weather information. The effectiveness of the proposed method is demonstrated by applying it to actual data taken at the Karatsu substation in Japan.     

Short-term air quality prediction using a case-based classifier

In the frame of air quality monitoring of urban areas the task of short-term prediction of key-pollutants concentrations is a daily activity of major importance. Automation of this process is desirable but development of reliable predictive models with good performance to support this task in operational basis presents many difficulties. In this paper we present and discuss the NEMO prototype that has been built in order to support short-term prediction of NO₂ maximum concentration levels in Athens, Greece. NEMO is based on a case-based reasoning approach combining heuristic and statistical techniques. The process of development of the system, its architecture and its performance, are described in this paper. NEMO performance is compared with that of a back propagating neural network and a decision tree. The overall performance of NEMO makes it a good candidate to support air pollution experts in operational conditions.