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Selected AbstractsA MATLAB toolbox for solving acid-base chemistry problems in environmental engineering applicationsCOMPUTER APPLICATIONS IN ENGINEERING EDUCATION, Issue 4 2005Chetan T. Goudar Abstract A MATLAB toolbox incorporating several computer programs has been developed in an attempt to automate laborious calculations in acid-base chemistry. Such calculations are routinely used in several environmental engineering applications including the design of wastewater treatment systems and for predicting contaminant fate and transport in the subsurface. The computer programs presented in this study do not replace student thinking involved in formulating the problem solving strategy but are merely tools that simplify the actual problem solving process. They encompass a wide variety of acid-base chemistry topics including equilibrium constant calculations, construction of distribution diagrams for mono and multiprotic systems, ionic strength and activity coefficient calculations, and buffer index calculations. All programs are characterized by an intuitive graphical user interface where the user supplies input information. Program outputs are either numerical or graphical depending upon the nature of the problem. The application of this approach to solving actual acid-base chemistry problems is illustrated by computing the pH and equilibrium composition of a 0.1 M Na2CO3 system at 30°C using several programs in the toolbox. As these programs simplify lengthy computations such as ionization fraction and activity coefficient calculations, it is hoped they will help bring more complicated problems to the environmental engineering classroom and enhance student understanding of important concepts that are applicable to real-world systems. The programs are available free of charge for academic use from the authors. © 2005 Wiley Periodicals, Inc. Comput Appl Eng Educ 13: 257,265, 2005; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.20051 [source] Evaluating explicit and implicit routing for watershed hydro-ecological models of forest hydrology at the small catchment scaleHYDROLOGICAL PROCESSES, Issue 8 2001C. L. Tague Abstract This paper explores the behaviour and sensitivity of a watershed model used for simulating lateral soil water redistribution and runoff production. In applications such as modelling the effects of land-use change in small headwater catchments, interactions between soil moisture, runoff and ecological processes are important. Because climate, soil and canopy characteristics are spatially variable, both the pattern of soil moisture and the associated outflow must be represented in modelling these processes. This study compares implicit and explicit routing approaches to modelling the evolution of soil moisture pattern and spatially variable runoff production. It also addresses the implications of using different landscape partitioning strategies. This study presents the results of calibration and application of these different routing and landscape partitioning approaches on a 60 ha forested watershed in Western Oregon. For comparison, the different approaches are incorporated into a physically based hydro-ecological model, RHESSys, and the resulting simulated soil moisture, runoff production and sensitivity to unbiased error are examined. Results illustrate that both routing approaches can be calibrated to achieve a reasonable fit between observed and modelled outflow. Calibrated values for effective watershed hydraulic conductivity are higher for the explicit routing approach, which illustrates differences between the two routing approaches in their representation of internal watershed dynamics. The explicit approach illustrates a seasonal shift in drainage organization from watershed to more local control as climate goes from a winter wet to a summer dry period. Assumptions used in the implicit approach maintain the same pattern of drainage organization throughout the season. The implicit approach is also more sensitive to random error in soil and topographic input information, particularly during wetter periods. Comparison between the two routing approaches illustrates the advantage of the explicit routing approach, although the loss of computational efficiency associated with the explicit routing approach is noted. To compare different strategies for partitioning the landscape, the use of a non-grid-based method of partitioning is introduced and shown to be comparable to grid-based partitioning in terms of simulated soil moisture and runoff production. Copyright © 2001 John Wiley & Sons, Ltd. [source] Estimation of Compartmental Half-lives of Organic Compounds , Structural Similarity versus EPI-SuiteMOLECULAR INFORMATICS, Issue 4 2007Ralph Kühne Abstract A k Nearest Neighbors (KNN) approach is developed to extrapolate from existing semiquantitative compartmental half-lives of organic compounds to respective data for untested substances. It is based on the evaluation of structural similarity through atom-centered fragments (ACFs). For the model development and leave-one-out cross-validation, a set of 293 compounds with reference half-lives for the four compartments air, water, soil, and sediment was taken from literature. Comparative analysis of the model performance with results based on EPI-Suite predictions of degradation rates due to indirect photolysis, biodegradation, and hydrolysis demonstrates the superiority of the new approach to predict compartmental half-lives. The latter are needed as input information for modeling the multimedia fate and life-time of organic compounds. The discussion includes an analysis of the problems associated with converting process-specific loss rates into compartmental half-lives. [source] Robust QFD: framework and a case studyQUALITY AND RELIABILITY ENGINEERING INTERNATIONAL, Issue 1 2007Kwang-Jae Kim Abstract Quality function deployment (QFD) provides a specific approach for ensuring quality throughout each stage of the product development. Since the focus of QFD is placed on the early stage of product development, the uncertainty in the input information of QFD is inevitable. If the uncertainty is neglected, the QFD analysis results can be misleading. This paper proposes an extended version of the QFD methodology, called Robust QFD, which is capable of considering the uncertainty of the input information and the resulting variability of the output. The proposed framework aims to model, analyze, and dampen the effects of the uncertainty and variability in a systematic manner. The proposed framework is demonstrated through a case study on the ADSL-based high-speed Internet service. Copyright © 2007 John Wiley & Sons, Ltd. [source] The Economics of Erosion and Sustainable Practices: The Case of the Saint-Esprit WatershedCANADIAN JOURNAL OF AGRICULTURAL ECONOMICS, Issue 2 2000Jean-Christophe Dissart This paper examines the economics of the adoption of sustainable production practices for soil erosion control. The research was conducted on three case farms within the Saint-Esprit watershed in Quebec using a two-stage process. The first stage involved the use of GIS (Geographical Information Systems) to record erosion characteristics (slope, etc.) for these farmers'fields. This erosion information was then included as input information in the second stage of the process. Mixed integer linear programming (MILP) was used to model both individual farms and the watershed. Increasing erosion constraints were applied to these models to investigate changes in crop production mixes for farms and the watershed. A comparison of the results (farms versus watershed) was used to investigate policy questions concerning an optimal erosion constraint for society. Results generated indicate that farms with higher net incomes would be advantaged by erosion constraints set at the watershed level, whereas farms with lower net revenues would be disadvantaged. Thus, trading of pollution permits could be encouraged. Cet article examine les aspects économiques de l'adoption de pratiques de production durables visant a réduire l'érosion du sol. La recherche fut effectuée sur trois fermes situées dans le has sin du Saint-Esprit au Québec, et impliqua un processus à deux étapes. Le premier étape consiste en l'utilisation du systéme d'informations géographiques " SIG " afin de noter les caractéristiques de l'érosion (pente, etc.) dans ces champs agricoles. Ces renseignements servirent de données au sein du deuxième étape. La méthode de programmation linéaire à nombres entiers mixtes fut employée afin de modéliser les fermes individuelles, ainsi que le bassin. Ensuite, les contraintes d,érosion furent appliquées sur ces modèles de manière croissante, et ce afin d'étudier les changements dans le melange des productions de cultures pour les fermes et le bassin. Une comparaison des résultats (fermes vs. bassin) fut accomplie pour examiner les questions de politiques pouvant mener à une contrainte d,érosion optimale pour la société. Les résultats obtenus démontrent que les fermes ayant des revenus nets élevés seraient avantagées par des contraintes d'érosion établies au niveau du bassin, tandis que les fermes aux revenus nets plus bas en seraient désavantagées. En conséquence, l'échange de permis de pollution est recommandé. [source] Belief-Independent Processes and the Generality Problem for ReliabilismDIALECTICA, Issue 1 2005Mark McEvoy The Generality Problem for process reliabilism is to outline a procedure for determining when two beliefs are produced by the same process, in such a way as to avoid, on the one hand, individuating process types so narrowly that each type is instantiated only once, or, on the other hand, individuating them so broadly that beliefs that have different epistemic statuses are subsumed under the same process type. In this paper, I offer a solution to the problem which takes belief-independent processes to be functions that take as inputs information about distal states of affairs, and produce beliefs as outputs. Processes are individuated narrowly, so as to avoid the latter aspect of the Generality problem, but, by holding process tokens to be of the same type when they take perceptually equivalent scenes as inputs, and produce beliefs of the same kind as outputs, the former aspect of the problem is avoided too. Having argued that this method of typing process tokens solves the Generality Problem, I then argue that my solution does not fall prey to objections that have been, or might be, raised for similar proposals. [source] | ||||||||||