Search results for "stabiilius"
showing 10 items of 11 documents
Theoretical study on travelling web dynamics and instability under non-homogeneous tension
2013
Problems of dynamics and stability of a moving web, travelling between two rollers at a constant velocity, are studied using analytical approaches. Transverse vibrations of the web are described by a partial differential equation that includes the centrifugal force, in-plane tension, elastic reaction and nonstationary inertial terms. The model of a thin elastic plate subjected to bending and non-homogeneous tension is used to describe the bending moment and the distribution of membrane forces. The stability of the plate is investigated with the help of studies of small out-of-plane vibrations. The influence of linearly distributed in-plane tension on the characteristics of the web vibration…
Dynamic analysis for axially moving viscoelastic panels
2012
In this study, stability and dynamic behaviour of axially moving viscoelastic panels are investigated with the help of the classical modal analysis. We use the flat panel theory combined with the Kelvin–Voigt viscoelastic constitutive model, and we include the material derivative in the viscoelastic relations. Complex eigenvalues for the moving viscoelastic panel are studied with respect to the panel velocity, and the corresponding eigenfunctions are found using central finite differences. The governing equation for the transverse displacement of the panel is of fifth order in space, and thus five boundary conditions are set for the problem. The fifth condition is derived and set at the in-…
Politics of Mobility and Stability in Authorizing European Heritage : Estonia’s Great Guild Hall
2019
AbstractKaasik-Krogerus scrutinizes the European Heritage Label (EHL) as an authorized heritage discourse (AHD) in the making. She analyses how the discourse is formed in a politics of mobility and stability between the local, national, and European scales resulting from the interplay of europeanization (of the national and local) and domestication (of the European). The chapter asks how this politics of mobility and stability is conducted to manage the scalar dissonance in one of the sites, the Great Guild Hall in Tallinn, Estonia. Kaasik-Krogerus argues that the politics conducted in the exhibitions works in two controversial ways: legitimizing mobility and stability as natural and simult…
Optimization and analysis of processes with moving materials subjected to fatigue fracture and instability
2013
We study systems of traveling continuum modeling the web as a thin elastic plate of brittle material, traveling between a system of supports at a constant velocity, and subjected to bending, in-plane tension and small initial cracks. We study crack growth under cyclic in-plane tension and transverse buckling of the web analytically. We seek optimal in-plane tension that maximizes a performance vector function consisting of the number of cycles before fracture, the critical velocity and process effectiveness. The present way of applying optimization in the studies of fracture and stability is new and affords an analytical tool for process analysis. peerReviewed
Stability of moving viscoelastic panels interacting with surrounding fluid
2012
We study a model describing the out-of-plane vibrations of an axially moving viscoelastic panel submerged in flowing fluid. The panel is assumed to travel at a constant velocity between two fixed supports, and it is modeled as a flat panel made of viscoelastic Kelvin-Voigt material. The fluid flow is modeled with the help of the added mass coefficients. The resulting dynamic equation is a partial differential equation of fifth order in space. Five boundary conditions are set for the studied problem. The behavior of the panel is analyzed with the help of its eigenvalues (eigenfrequencies). These characteristics are studied with respect to the velocity of the panel. In our study, we have incl…
Hopeananoklusterien synteesit, stabiilisuus ja monodispersiivisyys
2014
Tämän pro gradun kirjallisuusosassa tarkastellaan hopeananoklustereiden synteesejä. Tarkastelussa keskitytään erityisesti hopeaklustereiden stabiilisuuteen ja monodispersiivisyyteen. Hopeaklustereiden synteesimenetelmät on jaoteltu liuoksessa tehtyihin synteeseihin, kiinteässä olomuodossa tehtyihin synteeseihin ja templaattisynteeseihin. Lisäksi tarkastellaan hopean seosklustereiden synteesejä. Työn lopussa on lyhyet katsaukset klustereiden stabiilisuuteen vaikuttavista tekijöistä ja klustereiden karakterisoitimenetelmistä. Kokeellisen osan tarkoituksena oli syntetisoida hopeaklustereita käyttäen ligandina C5-tetrametoksiresorsinareeni-bis-tiakruunua ja muita resorsinareenipohjaisia molekyy…
Assessment of nonnegative matrix factorization algorithms for electroencephalography spectral analysis.
2020
AbstractBackgroundNonnegative matrix factorization (NMF) has been successfully used for electroencephalography (EEG) spectral analysis. Since NMF was proposed in the 1990s, many adaptive algorithms have been developed. However, the performance of their use in EEG data analysis has not been fully compared. Here, we provide a comparison of four NMF algorithms in terms of accuracy of estimation, stability (repeatability of the results) and time complexity of algorithms with simulated data. In the practical application of NMF algorithms, stability plays an important role, which was an emphasis in the comparison. A Hierarchical clustering algorithm was implemented to evaluate the stability of NM…
Longitudinal Stability of Reading Difficulties : Examining the Effects of Measurement Error, Cut-Offs, and Buffer Zones in Identification
2020
This study examined the stability of reading difficulties (RD) from grades 2 to 6 and focused on the effects of measurement error and cut-off selection in the identification of RD and its stability with the use of simulations. It addressed methodological limitations of prior studies by (a) applying a model-based simulation analysis to examine the effects of measurement error and cut-offs in the identification of RD, (b) analyzing a non-English and larger sample, and (c) examining RD in both reading fluency and reading comprehension. Reading fluency and reading comprehension of 1,432 Finnish-speaking children were assessed in grades 2 and 6. In addition to the use of single cut-off points on…
Static instability analysis of an elastic band travelling in the gravitational field
2011
Static instability analysis is performed for an axially moving elastic band, which is travelling at a constant velocity in a uniform gravitational field between two supports. The buckling of the band is investigated with the help of admitting small transverse deflections. The model of a thin elastic beam (panel) subjected to bending, centrifugal forces and nonhomogeneous tension (including a gravitational term) is used. Buckling analysis and estimation of the critical velocities of elastic instability are based on variational principles and variational inequalities. As a result, explicit formulas for upper and lower limits for critical velocities are found. It is shown analytically that a c…
Longitudinal tests of the theory of planned behaviour : A meta-analysis
2023
In a meta-analysis of longitudinal analyses of the theory of planned behaviour, we tested a series of extended or auxiliary theory-consistent hypotheses: construct stability, theory predictions within and between occasions, consistency over time or stationarity in theory effects and reciprocal effects among constructs. We also tested the effects of moderators on theory effects: measurement lag, health behaviour type (protection, risk) and specific health behaviours (alcohol, dietary and physical activity). A systematic search identified 87 studies eligible for inclusion. Meta-analytic structural equation models supported construct stability and theory effects within and between occasions. O…