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Parameters Leads (parameter + lead)
Selected AbstractsParameterization of charge model 3 for AM1, PM3, BLYP, and B3LYPJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 11 2003Jason D. Thompson Abstract We have recently developed a new Class IV charge model for calculating partial atomic charges in molecules. The new model, called Charge Model 3 (CM3), was parameterized for calculations on molecules containing H, Li, C, N, O, F, Si, S, P, Cl, and Br by Hartree,Fock theory and by hybrid density functional theory (DFT) based on the modified Perdew,Wang density functional with several basis sets. In the present article we extend CM3 to semiempirical molecular orbital theory, in particular Austin Model 1 (AM1) and Parameterized Model 3 (PM3), and to the popular BLYP and B3LYP DFT and hybrid DFT methods, respectively. For the BLYP extension, we consider the 6-31G(d) basis set, and for the B3LYP extension, we consider three basis sets: 6-31G(d), 6-31+G(d), and MIDI!6D. We begin with the previous CM3 strategy, which involves 34 parameters for 30 pairs of elements. We then refine the model to improve the charges in compounds that contain N and O. This modification, involving two new parameters, leads to improved dipole moments for amides, bifunctional H, C, N, O compounds, aldehydes, ketones, esters, and carboxylic acids; the improvement for compounds not containing N results from obtaining more physical parameters for carbonyl groups when the OCN conjugation of amides is addressed in the parameterization. In addition, for the PM3 method, we added an additional parameter to improve dipole moments of compounds that contain bonds between C and N. This additional parameter leads to improved accuracy in the dipole moments of aromatic nitrogen heterocycles with five-membered rings. © 2003 Wiley Periodicals, Inc. J Comput Chem 24: 1291,1304, 2003 [source] Comparison between the charring rate model and the conductive model of Eurocode 5FIRE AND MATERIALS, Issue 3 2009Paulo B. Cachim Abstract Eurocode 5, Part 1,2, presents several models for the calculation of fire resistance of timber structures. These models are based on the hypothesis that for temperatures above 300°C , wood is no longer able to sustain any stress, which makes the determination of the location of the 300°C isotherm decisive for the result provided by the models. In this paper, the charring rate model and the conductive model presented in Eurocode 5, Part 1,2 are compared regarding the determination of the location of the 300°C isotherm. The main wood parameters investigated are density, moisture content and anisotropy. The almost complete independence of the charring rate model from these parameters leads to some inconsistencies between the models. To reduce these inconsistencies some proposals to improve the conductive and the charring rate models are presented. Copyright © 2008 John Wiley & Sons, Ltd. [source] Bifurcation behaviour in parallel-connected boost convertersINTERNATIONAL JOURNAL OF CIRCUIT THEORY AND APPLICATIONS, Issue 3 2001H. H. C. Iu Abstract This paper describes the bifurcation phenomena of a system of parallel-connected d.c./d.c. boost converters. The results provide important information for the design of stable current sharing in a master,slave configuration. Computer simulations and experiments are performed to capture the effects of variation of some chosen parameters on the qualitative behaviour of the system. In particular, it is found that variation of some parameters leads to Neimark,Sacker bifurcation. Analysis is presented to establish the possibility of the bifurcation phenomena. Copyright © 2001 John Wiley & Sons, Ltd. [source] THE EFFECT OF INFORMATION ON A STOCHASTIC, SPATIALLY DISTRIBUTED FISHERYNATURAL RESOURCE MODELING, Issue 2 2003GREG CRIPE ABSTRACT. Survival rates and carrying capacities in a fishery may be strongly affected by variations in climatic factors. When the stock is under the control of a single manager, information about the stochastic growth parameters leads to improved economic returns. However, when the stock is transboundary, additional information concerning the stochastic parameters can lead to over harvesting and in turn to lower economic returns. When the harvests are taken sequentially by more than one fleet, additional information will benefit the first harvester while harming those who follow. [source] Modelling the impact of an influenza A/H1N1 pandemic on critical care demand from early pathogenicity data: the case for sentinel reportingANAESTHESIA, Issue 9 2009A. Ercole Summary Projected critical care demand for pandemic influenza H1N1 in England was estimated in this study. The effect of varying hospital admission rates under statistical uncertainty was examined. Early in a pandemic, uncertainty in epidemiological parameters leads to a wide range of credible scenarios, with projected demand ranging from insignificant to overwhelming. However, even small changes to input assumptions make the major incident scenario increasingly likely. Before any cases are admitted to hospital, 95% confidence limit on admission rates led to a range in predicted peak critical care bed occupancy of between 0% and 37% of total critical care bed capacity, half of these cases requiring ventilatory support. For hospital admission rates above 0.25%, critical care bed availability would be exceeded. Further, only 10% of critical care beds in England are in specialist paediatric units, but best estimates suggest that 30% of patients requiring critical care will be children. Paediatric intensive care facilities are likely to be quickly exhausted and suggest that older children should be managed in adult critical care units to allow resource optimisation. Crucially this study highlights the need for sentinel reporting and real-time modelling to guide rational decision making. [source] | ||||||||||