Search results for "Modeling and Simulation"
showing 10 items of 1561 documents
Using random networks to study the dynamics of respiratory syncytial virus (RSV) in the Spanish region of Valencia
2011
[EN] Seasonal fluctuations in the incidence of several respiratory infections are a feature of epidemiological surveys all around the world. This phenomenon is characteristic of influenza and respiratory syncytial virus pandemics. However, the explanation of the seasonal outbreaks of these diseases remains poorly understood. Many statistical studies have been carried out in order to provide a correlation of the outbreaks with climatic or social factors without achieving a definitive conclusion. Here we show that, in a random social network, self-sustained seasonal epidemics emerge as a process modulated by the infection probability and the immunity period after recovering from the infection…
Interindividual Differences in Treatment Effects based on Structural Equation Models with Latent Variables: An EffectLiteR Tutorial
2019
The investigation of interindividual differences in the effects of a treatment is challenging, because many constructs-of-interest in psychological research such as depression or anxiety are latent variables and modeling heterogeneity in treatment effects requires interactions and potentially nonlinear relationships. In this paper, we present a tutorial of the EffectLiteR approach (Mayer, Dietzfelbinger, Rosseel, & Steyer, 2016) that allows for estimating individual treatment effects based on latent variable models. We describe step by step how to apply the approach using the EffectLiteR software package with data from the multicenter randomized controlled trial of the Social Phobia…
Rosenberg's self‐esteem scale: Two factors or method effects
1999
Self‐esteem is one of the most studied constructs in psychology. It has been measured with a variety of methods and instruments. Although Rosenberg's (1965) self‐report scale is one of the most widely used, empirical evidence on factor validity of this scale is somewhat contradictory, with either 1 or 2 factors. The results of this study suggest the existence of a global self‐esteem factor underlying responses to the scale, although the inclusion of method effects is needed to achieve a good model fit.
Explaining Method Effects Associated With Negatively Worded Items in Trait and State Global and Domain-Specific Self-Esteem Scales
2013
Several investigators have interpreted method effects associated with negatively worded items in a substantive way. This research extends those studies in different ways: (a) it establishes the presence of methods effects in further populations and particular scales, and (b) it examines the possible relations between a method factor associated with negatively worded items and several covariates. Two samples were assessed: 592 high school students from Valencia (Spain), and 285 batterers from the same city. The self-esteem scales used were Rosenberg's Self-Esteem Scale, the State Self-Esteem Scale, and Self-Esteem 17. Anxiety was also assessed with the State-Trait Anxiety Inventory, and gend…
Soft computing-based aggregation methods for human resource management
2008
Abstract We are interested in the personnel selection problem. We have developed a flexible decision support system to help managers in their decision-making functions. This DSS simulates experts’ evaluations using ordered weighted average (OWA) aggregation operators, which assign different weights to different selection criteria. Moreover, we show an aggregation model based on efficiency analysis to put the candidates into an order.
Ultimate strain and deformability of elementary flax fibres
2011
Flax fibres possess high specific strength and stiffness, and thus are competitive in terms of mechanical properties with the traditional reinforcing fibres used in polymer-matrix composite materials. The mechanical properties of fibres have considerable variability that needs to be characterized and allowed for in the analysis of mechanical response of composites. In this study, the distribution of ultimate strain of elementary flax fibres and its dependence on gauge length is considered. The applicability of the modified Weibull distribution, used for fibre strength, to fibre ultimate strain is evaluated. A simplified relation of ultimate strain and fibre strength distributions is propos…
Analytical evaluation of structural response for stationary multicorrelated input
1990
Abstract An analytical procedure is presented which can drastically reduce computational effort in the evaluation of the spectral moments of an elastic linear multi-degree-of-freedom system subjected to a stationary multicorrelated input process. The reduction in computer time is possible since the cross-spectral moments of two oscillators can be obtained in recursive manner as a linear combination of the spectral moment of each oscillator taken separately, which is evaluated by means of a very fast numerical technique.
Analysis of pattern recognition by man using detection experiments.
1981
This paper addresses the problem of analyzing biological pattern recognition systems. As no complete analysis is possible due to limited observability, the theoretical part of the paper examines some principles of construction for recognition systems. The relations between measurable and characteristic variables of these systems are described. The results of the study are: 1. Human recognition systems can always be described by a model consisting of an analyzer (FA) and a linear classifier. 2. The linearity of the classifier places no limits on the universal validity of the model. The principle of organization of such a system may be put into effect in many different ways. 3. The analyzer f…
Performance potential for simulating spin models on GPU
2012
Graphics processing units (GPUs) are recently being used to an increasing degree for general computational purposes. This development is motivated by their theoretical peak performance, which significantly exceeds that of broadly available CPUs. For practical purposes, however, it is far from clear how much of this theoretical performance can be realized in actual scientific applications. As is discussed here for the case of studying classical spin models of statistical mechanics by Monte Carlo simulations, only an explicit tailoring of the involved algorithms to the specific architecture under consideration allows to harvest the computational power of GPU systems. A number of examples, ran…
New stage-discharge relationship for inclined non-rectangular weirs
2018
Abstract In this paper, the outflow process of inclined non-rectangular weirs is studied applying the dimensional analysis and the incomplete self-similarity theory. At first, a new stage-discharge equation, applicable for the non-rectangular weirs having a different geometrical shape (parabolic, semicircular, inverted semicircular), is theoretically deduced using a characteristic width. Then, this power stage-discharge relationship (Eq. (17) ) is calibrated and tested using measurements carried out by Raiknar for parabolic, semicircular and inverted semicircular weirs having different inclination respect to the vertical (10°, 20°, 30°, 40° and 45°). For each geometrical shape, the analysis…