Improvements in Air Quality Modelling by Using Surface Boundary Layer Parameters derived from Satellite Land Cover Data

Many atmospheric dispersion models include only simpletreatment of surface features to estimate the wind profilesand stability parameters. Detailed characterisation of theland cover, particularly in large and complex urbanconurbations, is especially important, as the surfacefeatures can vary significantly over the area. This paperdiscusses the use of satellite land cover data to derivespatially resolved surface boundary layer (SBL) parameters.These parameters have been used in an air quality model,PEARL (Prediction Air Quality in Urban and RegionalLocations) for estimating monthly and annual COconcentrations. Land cover data, derived from LANDSATThematic Mapper Imagery, has been used to estimate SBLparameters (surface roughness length, albeedo, Bowen ratioand anthropogenic heat flux) for a study area of 10000km² encompassing Greater London and the surroundingcounties. The SBL parameters have been assigned according tomajor land cover types for the whole area at a spatialresolution of 1 × 1 km. Predictions from two versions of the PEARL model (one with land cover data and one without)have been compared with each other and with measured data forannual and monthly CO concentrations from seven London airquality monitoring sites. This comparison shows thatdifferences between predicted and observed values can bereduced by up to a factor of three. The use of SBLparameters derived from land cover data also yields moredetailed predicted annual CO spatial patterns especially inand around suburban areas. The performance of both versionsof the model for monthly CO concentrations has been comparedwith a range of statistical measures. This comparisonconfirms that improved agreement is observed betweenmodelled and measured monthly CO concentrations when use ismade of spatially resolved SBL parameters.     

NONLINEAR SOLUTIONS OF THE BQUSSINESQ EQUATION AND COMPARISONS WITH FIELD OBSERVATIONS1

ABSTRACT: Two models based on variations of the one dimensional Boussinesq equation are presented. The models are formulated by treating each of the two nonlinearities appearing in the equation separately, and the resulting equations are solved by implicit finite difference techniques. The models have been used to predict drawdowns created from large scale pumping at an open coal mine pit dewatering project in Poland. The predictions were found to be in good agreement with data collected over a period of seven years.     

THE DEVELOPMENT OF A COMBINED WATER QUALITY INDEX1

ABSTRACT: Use-oriented benefits and treatment costs analysis has been incorporated into a water quality index to show an economically optimized concentration for the treatment of the pollutants and the resulting water quality. This combined water quality index can be used in decisionmaking at the federal and local government levels. Five major pollutants, i.e., coliforms, nitrogen, phosphorus, suspended solids, and detergent, have been considered for the municipal waste water. With each higher level of improvement the treatment costs increase accordingly and the benefits associated with the reuse of this treated waste water will increase too but not for the nutrient removal in agricultural use. The optimal concentration is determined when the marginal costs equal the marginal benefits. The combined water quality index is the combination of the maximum net benefits and the water quality index of the optimized residual concentrations. This water quality index is zero dollars for the Tucson region in this study. The possible reclaimed use of municipal waste water is for agricultural irrigation and recreational lakes for the Tucson region.     

COMPARATIVE STUDY OF FRESH-SALT WATER INTERFACES USING FINITE ELEMENT AND SIMPLE APPROACHES

ABSTRACT: The fresh-salt water interface in artesian aquifers has been investigated by various techniques on the basis of its analogy to the free surface in earth dams or cores of dams. Although various approximations are used, some more or less exact solutions exist. One of the simple methods, that would appeal to practical workers, was developed by the analysis of hydraulic forces. However, this method has not been checked thoroughly due to the lack of wide ranges of coverage by the more or less exact solutions. In this paper a suggested finite element method is used for the purpose of comparing with the method of hydraulic forces. The presented procedure eliminates some of the difficulties and uncertainties in current finite element procedures. Both methods proved to be in close agreement. Moreover, the hydraulic heads along the upper boundary of the artesian aquifer were found to be in close agreement with Dupuit's equation. The results of this investigation would greatly simplify the more complex management problems when the effects of discharge and/or recharge wells are added to the natural flow effects.     

PROBABILISTIC METHODS IN STREAM QUALITY MANAGEMENT1

ABSTRACT. Recent advances in water quality modelling have pointed out the need for stochastic models to simulate the probabilistic nature of water quality. However, often all that is needed is an estimate of the uncertainty in predicting water quality variables. First order analysis is a simple method of providing an estimate in the uncertainty in a deterministic model due to uncertain parameters. The method is applied to the simplified Streeter-Phelps equations for DO and BOD; a more complete Monte Carlo simulation is used to check the accuracy of the results. The first order analysis is found to give accurate estimates of means and variances of DO and BOD up to travel times exceeding the critical time. Uncertainty in travel time and the BOD decay constant are found to be most important for small travel times; uncertainty in the reaeration coefficient dominates near the critical time. Uncertainty in temperature was found to be a negligible source of uncertainty in DO for all travel times.     

Initial phase modelling in numerical explosion applied to process safety

The utilisation of computational fluid dynamics (CFD) in process safety has increased significantly in recent years. The modelling of accidental explosion via CFD has in many cases replaced the classical Multi Energy and Brake Strehlow methods. The benefits obtained with CFD modelling can be diminished if proper modelling of the initial phase of explosion is neglected. In the early stages of an explosion, the flame propagates in a quasi-laminar regime. Proper modelling of the initial laminar phase is a key aspect in order to predict the peak pressure and the time to peak pressure. The present work suggests a modelling approach for the initial laminar phase in explosion scenarios. Findings are compared with experimental data for two classical explosion test cases which resemble the common features in chemical process areas (confinement and congestion). A detailed analysis of the threshold for the transition from laminar to turbulent regime is also carried out. The modelling is implemented in a fully 3D Navier–Stokes compressible formulation. Combustion is treated using a laminar flamelet approach based on the Bray, Moss and Libby (BML) formulation. A novel modified porosity approach developed for the unstructured solver is also considered. Results agree satisfactorily with experiments and the modelling is found to be robust.     

Evaluating the usability of a commercial cooling vest in the Hong Kong industries

Objective. The provision of appropriate personal cooling vests is recognized as an effective measure to combat heat stress. However, personal cooling vests are not widely implemented in the Hong Kong industries. The current study aims to evaluate the usability of a hybrid cooling vest that is associated with the success of its application in industrial settings. Methods. A self-administrated questionnaire focusing on 10 subjective attributes of cooling effect, ergonomic design and usability of a hybrid cooling vest was administered with 232 occupational workers in the construction, horticultural and cleaning, airport apron services and kitchen and catering industries. Results. A structural equation model estimated by analysis of moment structures was constructed to evaluate the usability of the cooling vest, as influenced by cooling effect and ergonomic design. Results showed that cooling effect (path coefficient?=?0.69, p?p?Conclusions. The structural equation model is feasible to examine the complex nature of the structural relationships among the subjective perceptions of personal cooling vests. The empirical findings furnish sound evidence for further optimization of the hybrid cooling vest in terms of cooling effect and ergonomic design for occupational workers.     

Assessment of Air Quality, Emissions and Management in a Local Urban Environment

This paper describes one example of how the UK National Air Quality Strategy (NAQS) is implemented in a local urban environment. The paper reviews the beginning of this process, by examining the review and assessment procedures of the NAQS in the London Borough of Barnet. By the application of available UK tools of local air quality management (LAQM), the process began through analysis of the levels of local emissions and progressed onto modelling of current and future air quality. A map showing combined emission hotspot areas for the Borough indicated and higher emission rates occur in the south of the Borough and along the major transport corridors, as road sources dominate emissions. Dispersion modelling studies were also conducted for this purpose, using the screening models GRAM, PGRAM and ADMS Urban for an in-depth assessment. These analyses found that some local point sources and the majority of Borough roads with over 20,000 vehicles per day produced exceedances of the future objectives for air quality for some pollutants.Recommendations for the progression of LAQM in the Borough are made and include the update and expansion of the emissions information held for use in future modelling studies. The paper demonstrates the experience of implementing the Strategy, using the tools and procedures available for this purpose, in a local urban environment that is similar to many in the UK.     

九寨沟旅游者地方感对资源保护态度的影响

地方感是国外游憩地理学和环境心理学的研究热点,旅游者地方感对其资源保护态度与行为的影响是地方感应用研究的重要内容。以九寨沟为例,设计量表测量了旅游者的地方感及其资源保护态度,通过构建结构方程模型探讨了旅游者地方感与其资源保护态度的关系。研究结果表明：（1）九寨沟的自然风景、社会人文对旅游功能有显著的正向影响,自然风景、旅游功能对旅游者的情感依恋有显著的正向影响;（2）旅游者的资源保护态度直接受其对九寨沟的情感依恋的影响,九寨沟的自然风景、社会人文和旅游功能主要通过旅游者的情感依恋影响资源保护态度,情感依恋在其中起着媒介作用;（3）对自然风景的感知评价是影响旅游者的资源保护态度的主要因素;（4）感知体验水平越高的旅游者,对九寨沟资源环境保护的重要性的认同程度也越高。最后讨论了增强旅游者资源保护意识的途径以及地方感研究的实际意义     

自主神经功能紊乱化学品的机器学习筛查模型

化学品可以引起继发性自主神经功能紊乱(autonomic dysfunction, AD),对人体健康造成危害。通过动物实验和临床测试手段筛查AD化学品,过程复杂、耗时长且成本高,有必要发展高通量的筛查方法。目前,化学品诱发AD的机制复杂,尚缺乏筛查AD化学品的机器学习模型。本研究基于文献和数据库挖掘,构建了涵盖4种AD临床不良症状(直立性低血压、失禁、尿失禁、肛门失禁)的数据集,包括466种阳性数据,427种阴性数据。基于该数据集,计算ToxPrint毒性指纹,采用5种机器学习算法(决策树、支持向量机、k近邻、随机森林、梯度提升决策树)构建了AD化学品的筛查模型。随机森林模型的分类性能最优,训练集准确率达0.738,验证集准确率达0.737,若考虑模型应用域,当相似性阈值为0.75时,验证集准确率提高至0.752。此外,本研究耦合SHAP(SHapley Additive exPlanations)方法和子结构片段频率分析方法,揭示了诱发AD的16种警示子结构,包括9种键、3种链、3种环和1种基团结构。基于所发展的机器学习筛查模型,拓展了对AD机制的认识和理解,为神经毒性化学品的筛查和评价提供参考。