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Additional Models (additional + models)
Selected AbstractsOn the Pervasiveness of Home Market EffectsECONOMICA, Issue 275 2002Keith Head Paul Krugman's model of trade predicts that the country with the relatively large number of consumers is the net exporter and hosts a disproportionate share of firms in the increasing returns sector. He terms these results ,home market effects'. This paper analyses three additional models featuring increasing returns, firm mobility, and trade costs to assess the robustness of home market effects to alternative modelling assumptions. We find strikingly similar results for two of the models that relax assumptions about the nature of demand, competition and trade costs. However, a model that links varieties to nations rather than firms can generate opposite results. [source] Factors influencing territorial occupancy and reproductive output in the Booted Eagle Hieraaetus pennatusIBIS, Issue 4 2006JOSÉ E. MARTÍNEZ During a 7-year research project in a forested area of southeastern Spain, we studied territorial occupancy and reproductive success in a Booted Eagle Hieraaetus pennatus population. We monitored 65 territories, gathering information on 406 occupancy events and 229 breeding attempts, including those of two potential competitors, the Northern Goshawk Accipiter gentilis and the Common Buzzard Buteo buteo. Generalized linear mixed models were used to explain occupancy and productivity, by evaluating the relative contribution of three different types of variables (habitat, competition and past events) and considering territory as a random effect. We examined a set of a priori hypothesized models, together with a number of additional models, and selected the best models following an information-theoretic approach. Our best models related territorial occupancy and productivity to previous breeding success (the fledging of one or two young), which appeared to be the most important factor determining the probability of reoccupation and the reproductive output in the subsequent year. The best occupation model revealed that the probabilities of occupancy were also conditioned by a competition variable (intraspecific nearest-neighbour distance) and two habitat variables (the location of the nest on the valley slope and the distance to the nearest forest track). Unlike the best occupation model, however, the selected model for reproductive output did not incorporate any competition variable besides previous breeding success, but included another two habitat variables (the effects of trunk height and NNE orientation). [source] Predictive adaptive control of plants with online structural changes based on multiple modelsINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 8 2008J. M. Lourenço Abstract The objective of this paper is to present a new algorithm to improve the adaptation rate of a predictive adaptive controller. For that sake, the possible plant dynamic outcomes are covered by a bank of models. Each model is used to re-initialize the adaptive controller every time there is a large change in dynamics. The contribution of the paper consists in the development of a procedure that includes additional models in the bank when found suitable according to defined criteria. The algorithm is demonstrated in a benchmark problem consisting of the position control of two masses coupled by a spring of varying stiffness. Copyright © 2008 John Wiley & Sons, Ltd. [source] Simultaneous refinement of structure and microstructure of layered materialsJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 1 2004Matteo Leoni The recursive description of stacking in layered crystals, originally developed by Treacy et al. [Proc. R. Soc. London Ser. A (1991), 433, 499,520] and implemented in the DIFFaX code, is enclosed in a non-linear least-squares minimization routine and combined with additional models (of specimen-related broadening and instrumental broadening) to allow the simultaneous refinement of both structural and microstructural parameters of a layered crystal. This implementation is named DIFFaX+. As examples, the refinements both of a simulated pattern of diamond, showing fault clustering, and of the observed powder pattern of a synthetic stoichiometric nanocrystalline chrysotile are reported. [source] Student and Teacher Perceptions of School Climate: A Multilevel Exploration of Patterns of DiscrepancyJOURNAL OF SCHOOL HEALTH, Issue 6 2010Mary M. Mitchell PhD BACKGROUND: School climate has been linked with improved academic achievement and reduced discipline problems, and thus is often a target of school improvement initiatives. However, few studies have examined the extent to which student and teacher perceptions vary as a function of individual, classroom, and school characteristics, or the level of congruence between teachers' and their students' perceptions of school climate. METHODS: Using data from 1881 fifth-grade students and their 90 homeroom teachers, we examined parallel models of students' and teachers' perceptions of overall school climate and academic emphasis. Two additional models were fit that assessed the congruence between teacher and student perceptions of school climate and academic emphasis. RESULTS: Multilevel analyses indicated that classroom-level factors were more closely associated with teachers' perceptions of climate, whereas school-level factors were more closely associated with the students' perceptions. Further analyses indicated an inverse association between student and teacher ratings of academic emphasis, and no association between student and teacher ratings of overall climate. CONCLUSIONS: Teacher ratings were more sensitive to classroom-level factors, such as poor classroom management and proportion of students with disruptive behaviors, whereas student ratings were more influenced by school-level factors such as student mobility, student-teacher relationship, and principal turnover. The discrepancy in ratings of academic emphasis suggests that while all of the respondents may have shared objectively similar experiences, their perceptions of those experiences varied significantly. These results emphasize the importance of assessing both student and teacher perceptions in future research on school climate. [source] A Co-Simulation Approach for the 3D Dynamic Simulation of Vehicles Considering Sloshing in Cargo and Fuel TanksPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2009Florian Fleissner The sloshing of liquids in cargo and fuel tanks mounted on vehicles can have a significant influence on the vehicle's driving dynamics and stability. To evaluate and optimize the quality of tank designs, we propose a co-simulation approach that consists of a coupled multibody system simulation for the vehicle and a Discrete Element Method and Smoothed Particle Hydrodynamics simulation for the sloshing cargo. This approach is beneficial especially for the simulation of fluid cargos, as Smoothed Particle Hydrodynamics does not require additional models to track and reconstruct free fluid surfaces. By means of dynamic 3D simulations of a double lane change maneuvers we compare the two different cargo models and demonstrate the viability of the co-simulation approach. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] BML revisited: Statistical physics, computer simulation, and probability,COMPLEXITY, Issue 2 2006Raissa M. D'Souza Abstract Statistical physics, computer simulation, and discrete mathematics are intimately related through the study of shared lattice models. These models lie at the foundation of all three fields, are studied extensively, and can be highly influential. Yet new computational and mathematical tools may challenge even well-established beliefs. Consider the BML model, which is a paradigm for modeling self-organized patterns of traffic flow and first-order jamming transitions. Recent findings, on the existence of intermediate states, bring into question the standard understanding of the jamming transition. We review the results and show that the onset of full-jamming can be considerably delayed based on the geometry of the system. We also introduce an asynchronous version of BML, which lacks the self-organizing properties of BML, has none of the puzzling intermediate states, but has a sharp, discontinuous, transition to full jamming. We believe this asynchronous version will be more amenable to rigorous mathematical analysis than standard BML. We discuss additional models, such as bootstrap percolation, the honey-comb dimer model and the rotor-router, all of which exemplify the interplay between the three fields, while also providing cautionary tales. Finally, we synthesize implications for how results from one field may relate to the other, and also implications specific to computer implementations. © 2006 Wiley Periodicals, Inc. Complexity, 12, 30,39, 2006 [source] | ||||||||||