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Empirical Modeling (empirical + modeling)

Distribution by Scientific Domains
Business, Economics, Finance and Accounting28%

Selected Abstracts

STATEWIDE EMPIRICAL MODELING OF BACTERIAL CONTAMINATION OF SURFACE WATERS,

JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 3 2006
James D. Wickham
ABSTRACT: Bacterial contamination of surface waters is attributed to both urban and agricultural land use practices and is one of the most frequently cited reasons for failure to meet standards established under the Clean Water Act (CWA) (P.L. 92,500). Statewide modeling can be used to determine if bacterial contamination occurs predominantly in urban or agricultural settings. Such information is useful for directing future monitoring and allocating resources for protection and restoration activities. Logistic regression was used to model the likelihood of bacterial contamination using watershed factors for the state of Maryland. Watershed factors included land cover, soils, topography, hydrography, locations of septic systems, and animal feeding operations. Results indicated that bacterial contamination occurred predominantly in urban settings. Likelihood of bacterial contamination was highest for small watersheds with well drained and erodible soils and a high proportion of urban land adjacent to streams. The number of septic systems and animal feeding operations and the amount of agricultural land were not significant explanatory factors. The urban infrastructure tends to "connect" more of the watershed to the stream network through the creation of roads, storm sewers, and wastewater treatment plants. This may partly explain the relationship between urbanization and bacterial contamination found in this study. [source]

Empirical Modeling of Butyl Acrylate/Vinyl Acetate/Acrylic Acid Emulsion-Based Pressure-Sensitive Adhesives

MACROMOLECULAR MATERIALS & ENGINEERING, Issue 5 2004
Renata Jovanovic
Abstract Summary: Butyl acrylate/vinyl acetate/acrylic acid (BA/VAc/AA) emulsion latexes were produced in a semi-batch mode. The objective was to generate polymers with properties favoring their application as pressure-sensitive adhesives. The influence of the individual monomer concentrations on final properties such as glass transition temperature (Tg), peel strength, shear strength and tack was investigated. To obtain the maximum amount of information in a reasonable number of runs, a constrained three-component mixture design was used to define the experimental conditions. Latexes were coated onto a polyethylene terephthalate carrier and dried. Different empirical models (e.g. linear, quadratic and cubic mixture models) governing the individual properties (i.e. Tg, peel adhesion, shear resistance and tack) were developed and evaluated. In the given experimental region, no single model was found to fit all of the responses (i.e. the final properties). However, in all models the most significant factor affecting the final properties was the AA concentration, followed by the VAc concentration. Shear strength contour lines over the investigated region. [source]

Absorption and fluorescence properties of acridinones, thioacridinones, aminoacridines and related crown ethers

JOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 5 2001
Anne-Marie Patellis
We report a study on the absorptive and emissive properties of 9-acridinones, 9-thioacridinones and 9-aminoacridines including six crown ether derivatives. The effect of solvents and of the addition of cations (Na+, K+, Ca2+ and Mg2+) on these properties has been studied. The absorption of the crown ether derivative of 9-thioacridinone is sensitive to solvents while the fluorescence of crown ethers derived from 9-aminoacridines shows some specificity towards cations. Empirical modeling was used to discuss the emission characteristics of these compounds. [source]

Meshing noise effect in design of experiments using computer experiments

ENVIRONMETRICS, Issue 5-6 2002
J. P. Caire
Abstract This work is intended to show the influence of grid length and meshing technique on the empirical modeling of current distribution in an industrial electroplating reactor. This study confirms the interest of usual DOEs for computer experiments. Any 2D mesh generator induced, in this sensitive case, a significant noise representing only less than 5 per cent of the response. The ,experimental error' obeys a normal distribution and the associated replicate SDs represents 20 per cent of the global residual standard deviation. The geometry seems also to influence the corresponding noise. If the current density uniformity could be considered as a severe test, it is obvious that the noise generated by meshing would be amplified for 3D grids that will be in common use in future years. Copyright © 2002 John Wiley & Sons, Ltd. [source]

What Determines Rule of Law?

KYKLOS INTERNATIONAL REVIEW OF SOCIAL SCIENCES, Issue 3 2009
An Empirical Investigation of Rival Models
SUMMARY In the growing literature on the creation of institutions, the theories emphasizing colonial origin (Mauro, 1995), legal origin and religious affiliation (La Porta et al., 1999), Western European influence (Hall and Jones, 1999), and settler mortality (Acemoglu et al., 2001), have been especially influential. The validity and influence of these studies rests heavily on empirical modeling, which, since the theories are obviously closely related, might actually capture the same primary mechanism. It is therefore unclear whether the empirical relationships found are the same or if they are different. Therefore, this paper takes the empirical models seriously in order to discriminate among the existing models and to identify the model and variables that best explain the variation in institutional quality. The aim of this paper is thus to provide answers to the following questions: (i) Is there one model which explains more of the variation in institutional quality than the other models? (ii) Do these models capture the same information? And (iii), if we let the information in the data decide, which combination of variables would be selected? [source]

The Role of Universities in Building Local Economic Capacities

POLITICS & POLICY, Issue 2 2008
Michael Taylor
As the knowledge economy develops and intensifies, increasing pressure is being placed on universities to help in local economic capacity building to meet the challenges of globalization. This article explores this expanded university role from the perspective of the provision of policy analysis and advice they can provide. It proposes the use of mixed-methods analysis, combining informed empirical modeling and "intensive" case studies to reveal local economic processes. An analysis of Australia's regional problems to exemplify this approach highlights the significance of "enterprising human capital" in promoting regional economic growth and suggests a policy prescription that includes enterprising education. In contradistinction, using U.K. evidence, the pitfalls of entrepreneurship education are outlined as it relates to the role of universities in local economic capacity building. The study calls for dialogue to bring about radical rethinking of policy analysis, advice, and the role universities can play in local economic capacity building. [source]

Land Market Interactions between Heterogeneous Agents in a Heterogeneous Landscape,Tracing the Macro-Scale Effects of Individual Trade-Offs between Environmental Amenities and Disamenities

CANADIAN JOURNAL OF AGRICULTURAL ECONOMICS, Issue 4 2009
Tatiana Filatova
Heterogeneity in both the spatial environment and economic agents is a crucial driver of land market dynamics. We present an agent-based land market model where land from agriculture use is transferred into urban. The model combines the microeconomic demand, supply, and bidding foundations of spatial economics models with the spatial heterogeneity of spatial econometric models in a single methodological platform. Heterogeneous agents exchange heterogeneous spatial goods via simulated bilateral market interactions. We model a coastal city where both coastal amenities and flooding or erosion disamenities drive land market outcomes, facilitating separate analysis of the effects of each driver on land rents and land development patterns. We also analyze the implications of homogeneous versus heterogeneous but unbiased flood risk perceptions. Since buyers with low risk perceptions drive market outcomes, spatial development under heterogeneous risk perceptions differs qualitatively, with more expansion into risky areas. Our results highlight the shortcomings of policy models based on representative agent assumptions and the importance of including agent-level data in empirical modeling. L'hétérogénéité de l'environnement spatial et des agents économiques constitue un élément moteur crucial de la dynamique du marché foncier. Nous présentons un modèle multi-agent du marché foncier dans lequel des terres agricoles ont été transférées pour des fins urbaines. Le modèle combine les fondements microéconomiques de la demande, de l'offre et des enchères de modèles de l'économie spatiale avec l'hétérogénéité spatiale des modèles de l'économétrie spatiale dans une plateforme méthodologique unique. Les agents hétérogènes échangent des biens hétérogènes par le biais du jeu des forces du marché bilatéral simulé. Nous avons modélisé une ville côtière où les agréments côtiers et les désagréments causés par les inondations ou l'érosion influent sur le marché foncier, facilitant l'analyse individuelle des effets de chaque élément moteur sur les loyers fonciers et les modèles d'aménagement de terrain. Nous avons également analysé les répercussions des perceptions homogènes et hétérogènes mais non biaisées à l'égard du risque d'inondation. Étant donné que les acquéreurs qui ont de faibles perceptions du risque motivent les effets du marché, le développement spatial selon des perceptions hétérogènes à l'égard du risque varie qualitativement, avec plus d'expansion dans les zones à risque. Nos résultats ont mis en lumière les lacunes des modèles de politiques fondés sur les hypothèses d'un agent représentatif et l'importance d'inclure des données sur l'hétérogénéité des agents dans la modélisation empirique. [source]