COMPARISON OF PROCESS‐BASED AND ARTIFICIAL NEURAL NETWORK APPROACHES FOR STREAMFLOW MODELING IN AN AGRICULTURAL WATERSHED1

ABSTRACT: The performance of the Soil and Water Assessment Tool (SWAT) and artificial neural network (ANN) models in simulating hydrologic response was assessed in an agricultural watershed in southeastern Pennsylvania. All of the performance evaluation measures including Nash‐Sutcliffe coefficient of efficiency (E) and coefficient of determination (R²) suggest that the ANN monthly predictions were closer to the observed flows than the monthly predictions from the SWAT model. More specifically, monthly streamflow E and R² were 0.54 and 0.57, respectively, for the SWAT model calibration period, and 0.71 and 0.75, respectively, for the ANN model training period. For the validation period, these values were ?0.17 and 0.34 for the SWAT and 0.43 and 0.45 for the ANN model. SWAT model performance was affected by snowmelt events during winter months and by the model's inability to adequately simulate base flows. Even though this and other studies using ANN models suggest that these models provide a viable alternative approach for hydrologic and water quality modeling, ANN models in their current form are not spatially distributed watershed modeling systems. However, considering the promising performance of the simple ANN model, this study suggests that the ANN approach warrants further development to explicitly address the spatial distribution of hydrologic/water quality processes within watersheds.     

EVAPOTRANSPIRATION DYNAMICS AT AN ECOHYDROLOGICAL RESTORATION SITE: AN ENERGY BALANCE AND REMOTE SENSING APPROACH1

ABSTRACT: Little work is reported where spatial methods are employed to monitor evapotranspiration (ET) changes as a result of vegetation and wetland restoration. A remote sensing approach with the Surface Energy Balance Algorithm for Land (SEBAL) for estimating ET at The Nature Conservancy's Glacial Ridge prairie‐wetland restoration site in northwestern Minnesota is presented. The calibrated 24‐hour ET from SEBAL was estimated with an average error of prediction of ?4.3 percent. Monthly, interseasonal, and seasonal ET for the period of June to September (2000 to 2003) from three adjacent land‐uses: a hydrologic control preserved wetland; a treated or restored site; and a nontreated or impacted wetland, were used in the study. Results from comparing ET behavior to the preserve suggest restoration efforts have affected monthly and seasonal ET within the treated site. Spatial average standard deviations of the seasonal ET within the preserve, treated, and nontreated sites give 47.3, 75.7, and 109.9 mm, respectively, suggesting hydrologic stabilization within the treated site. Monthly and interseasonal comparisons show similar behavior to that of the seasonal data, where monthly correlations suggest increasing agreement within the treated site, approaching those within the preserve.     

微波消解石墨炉原子吸收法测定空气中的锰(铅)

本文介绍了用微波消解技术消解滤膜以测定空气中的锰（铅）的方法，与传统的稀硝酸浸出法、流酸-灰化法相比，微波消解更加简单、快速、节省、准确、沾污少、环境污染少，回收率高。     

Designating Air Quality Management Areas (AQMAs) in the UK Implications for Securing UK Air Quality Objectives

Across the United Kingdom, the majority of local authoritieshave now completed their first phase of local air qualityreview and assessment work, as required under the AirQuality Strategy for England, Scotland, Wales and NorthernIreland (DETR, 2000a). Emerging from this first phasework is an anticipated suite of over 110 Air QualityManagement Areas (AQMAs). These areas are identifiedlocations where one or more of the national air qualityobjectives are predicted to exceed by specific target dates,and their spatial extent and shape is emerging as highlyvariable. Local authorities are guided to use a variety ofscientific tools to underpin the scientific assessments, anda consideration of uncertainty in both the tools used andsubsequent delineation of AQMAs is likely to affect theemerging management areas significantly. With subsidiarity underpinning the process of local air qualitymanagement (LAQM), local decision-making is anticipated toinfluence the outcome of the LAQM process in its entirety,with the declaration of AQMAs necessitating the preparationand implementation of air quality action plans. UKexperience of the effective management of local air quality,through the designation of AQMAs, demonstrates a valuableframework for other European countries developing mechanismsto manage air quality locally.     

Effects of Starch Moisture on Properties of Wheat Starch/Poly(Lactic Acid) Blend Containing Methylenediphenyl Diisocyanate

Methylenediphenyl diisocyanate was found to improve the interfacial interaction between poly(lactic acid)(PLA) and granular starch. The objective of this research was to study the effect of starch moisture content on the interfacial interaction of an equal-weight blend of wheat starch and PLA containing 0.5% methylenediphenyl diisocyanate by weight. Starch moisture (10% to 20%) had a negative effect on the interfacial binding between starch and PLA. The tensile strength and elongation of the blend both decreased as starch moisture content increased. At 20% moisture level, the starch granules embedded in the PLA matrix were observed to be swollen, resulting in poor strength properties and high water absorption by the blend.     

广安市大气环境质量现状评价与优化布点监测

采用网格布点法对广安市城区大气环境质量进行了第一次普查监测，利用模糊综合评判法做出简易的现状评价，并评选出了一组优化点位作为日后大气自动化监测点位。     

简易石灰石/石膏湿法烟气脱硫技术在连州电厂的应用

在介绍了连州电厂的广东省第一套简易石灰石／石膏湿法烟气脱硫（FGD）系统主要设计参数和工艺流程的基础上，重点对FGD系统在近2年的运动过程中出现的主要问题进行了分析，包括系统与锅炉的相互影响，烟道腐蚀问题，脱硫石膏与灰渣水的混排及吸收塔内搅拌器叶片的损坏等，同时从技术，经济两方面对该套FGD系统进行了总体的评价。     

计算机局域网络保密措施

随着计算机的普及 ,局域网络越来越广为利用 ,但也出现了相应的失密问题。本文从信息及实体两个方面 ,论述了局域网络的保密措施。     

隧洞施工通风系统事故树分析

在采矿、铁路、公路及水利水电工程中，常常采用长距离隧洞或隧道来穿越高山。而隧洞的施工以其施工技术复杂、难度大、风险高，经常成为控制工程工期的主要环节，隧洞施工中的通风换气系统，关系到施工能否顺利进行和施工作业人员的人身安全，根据隧洞施工通风系统的运行特点，采用安全系统分析中的事故树（FTA）方法，对隧洞施工中通风系统的安全性进行定性分析，找出影响通风安全的主要因素，并提出了通风安全管理对策，可以保证施工作业的顺利进行和人身安全，提高整个施工作业的安全度。     

计算流体力学(CFD)中的迭代法及其并行计算方法

应用计算流体力学 (CFD)方法分析事故原因已被广泛采用 ,笔者针对事故理论分析和流体计算过程中 ,运用CFD方法所存在计算量大的问题 ,分析和讨论了几种古典迭代法及其并行计算方法