Search results for "modeling"
showing 10 items of 4489 documents
Links and Bifurcations in Nonsingular Morse–Smale Systems
1997
Wada's theorem classifies the set of periodic orbits in NMS systems on S3 as links, that can be written in terms of six operations. This characterization allows us to study the topological restrictions that links require to suffer a given codimension one bifurcation. Moreover, these results are reproduced in the case of NMS systems with rotational symmetries, introducing new geometrical tools.
3D objects descriptors methods: Overview and trends
2017
International audience; Object recognition or object's category recognition under varying conditions is one of the most astonishing capabilities of human visual system. The scientists in computer vision have been trying for decades to reproduce this ability by implementing algorithms and providing computers with appropriate tools. Hence, several intelligent systems have been proposed. To act in this field, numerous approaches have been proposed. In this paper we present an overview of the current trend in 3D objects recognition and describe some representative state of the art methods, highlighting their limits and complexity.
Skewness in individual stocks at different investment horizons
2002
Abstract This paper examines the (a)symmetry of several individual stock returns at different investment horizons: daily, weekly and monthly. While some asymmetries are observed in daily returns, they disappear almost completely in weekly and monthly returns. The explanation for this fact lies in the convergence to normality that takes place when the investment horizon increases. These features allow one to question several financial models; in particular, they question the preference for positive skewness as a factor for investments in stock markets.
New-stage discharge relationships for free and submerged sluice gates
2012
Abstract The flow movement through a sluice gate is investigated for both free and submerged flow conditions. For free flow condition, the current dimensionless formula, indicated acceptable accuracy; while for submerged flow condition it was modified especially for low submerged condition. In this regard, Buckingham theorem along with the Incomplete Self-Similarity concept was employed and a new stage–discharge relationship was developed accordingly. Also, to achieve a suitable formula for submerged flow condition being accurate in low submergence, the maximum tailwater depth allowing the free flow condition and head loss factor were identified as missing parameters in the functional dimen…
New stage-discharge relationship for cylindrical and semi-cylindrical edged sluice gates
2019
Abstract Gates are simple hydraulic structures which have been widely used for flow control and measurement in irrigation networks. In this paper new sluice gates with cylindrical and semi-cylindrical edges were introduced and the flow movement below these types of gates was experimentally investigated for both free- and submerged-flow conditions. The Buckingham theorem of dimensional analysis and the self-similarity theory were applied for developing the stage-discharge relationships for the two investigated flow conditions. For these cylindrical and semi-cylindrical edged gates and a free-flow condition, the proposed stage-discharge relationship was characterized by an estimate error less…
ENTROPY SOLUTIONS IN THE STUDY OF ANTIPLANE SHEAR DEFORMATIONS FOR ELASTIC SOLIDS
2000
The concept of entropy solution was recently introduced in the study of Dirichlet problems for elliptic equations and extended for parabolic equations with nonlinear boundary conditions. The aim of this paper is to use the method of entropy solutions in the study of a new problem which arise in the theory of elasticity. More precisely, we consider here the infinitesimal antiplane shear deformation of a cylindrical elastic body subjected to given forces and in a frictional contact with a rigid foundation. The elastic constitutive law is physically nonlinear and the friction is described by a static law. We present a variational formulation of the model and prove the existence and the uniquen…
The accumulation of problems of social functioning as a long-term process: Women and men compared
2000
Structural equation modelling was used to analyse the developmental processes involved in the accumulation of problems of social functioning from age 8 to age 36 in men ( n = 152) and women ( n = 145). The accumulation of risk factors in childhood and adolescence, including low control of emotions (aggressiveness and anxiety), school problems (poor adjustment, success, and motivation), and problems in the family (parental drinking and low socioeconomic status), predicted career instability, early timing of parenthood, and a sense of failure at age 27 in both sexes. Similarly, the accumulation of problems of social functioning (e.g. poor financial standing, poor intimate relationships, and d…
Resilience and Parental Burnout Among Finnish Parents During the COVID-19 Pandemic: Variable and Person-Oriented Approaches.
2021
During the coronavirus disease 2019 (COVID-19) crisis, different personality characteristics may have influenced parental well-being in different ways. In the present study, we combined variable and person-oriented approaches and examined relationships between resilience, parental burnout, and perfectionism during the lockdown. We first used structural equation modeling to assess the paths between variables. We then used latent profile analysis to examine different profiles of parents based on resilience, perfectionism, and symptoms of parental burnout. Finally, we examined how these profiles differ in terms of relevant background variables. The results showed that resilience predicted par…
The Task and Ego Orientation in Sport Questionnaire: Testing for Measurement Invariance and Latent Mean Differences in Spanish and Portuguese Adolesc…
2010
Within the theoretical framework of achievement goals (Nicholls, 1989), Duda and Nicholls (see Duda, 1989; Duda & Whitehead, 1998) developed the Task and Ego Orientation in Sport Questionnaire (TEOSQ) to assess individual differences in achievement goal orientations. This study searches for validity evidence of the TEOSQ in the case of Spanish (2473) and Portuguese (2486) junior high school. The results showed that factor structure, factor loadings, and intercepts could be considered invariant across groups. Between group differences in latent means showed slightly higher mean scores for the Spanish group for both factors. The results also provide high support for the internal consistency o…
Learning strategies explaining differences in reading proficiency. Findings of Nordic and Baltic countries in PISA 2009
2015
Abstract There are useful metacognitive learning strategies improving learning results significantly. Students can be trained to use them to achieve a higher level of proficiency in different academic domains, including reading. The current study was aimed to discover how student awareness and use of learning strategies explains differences in reading literacy test results, using PISA (the Program for International Student Assessment) 2009 data of three Nordic and three Baltic countries. The student level differences appeared partly due to the differences between schools, in the Baltic countries more than in the Nordic countries, which is considered a concern in the countries stating the eq…