Search results for "matemaattiset mallit"

Analysis of errors caused by incomplete knowledge of material data in mathematical models of elastic media

2011

Bifurcation method of stability analysis and some applications

2014

In this paper a new approach to the analysis of implicitly given function- als is developed in the frame of elastic stability theory. The approach gives an effective procedure to analyse stability behaviour, and to determine the bifur- cation points. Examples of application of the proposed approach for analysis of stability are presented, more precisely we consider the stability problem of an axially moving elastic panel, with no external applied tension, performing transverse vibrations. The analysis is applicable for many practical cases, for example, paper making and band saw blades.

Harmonic balance analysis of pull-in range and oscillatory behavior of third-order type 2 analog PLLs

2020

The most important design parameters of each phase-locked loop (PLL) are the local and global stability properties, and the pull-in range. To extend the pull-in range, engineers often use type 2 PLLs. However, the engineering design relies on approximations which prevent a full exploitation of the benefits of type 2 PLLs. Using an exact mathematical model and relying on a rigorous mathematical thinking this problem is revisited here and the stability and pull-in properties of the third-order type 2 analog PLLs are determined. Both the local and global stability conditions are derived. As a new idea, the harmonic balance method is used to derive the global stability conditions. That approach…

Stability and oscillation of dynamical systems : theory and applications

2008

Discrete exterior calculus for photonic crystal waveguides

2022

The discrete exterior calculus (DEC) is very promising, though not yet widely used, discretization method for photonic crystal (PC) waveguides. It can be seen as a generalization of the finite difference time domain (FDTD) method. The DEC enables efficient time evolution by construction and fits well for nonhomogeneous computational domains and obstacles of curved surfaces. These properties are typically present in applications of PC waveguides that are constructed as periodic structures of inhomogeneities in a computational domain. We present a two-dimensional DEC discretization for PC waveguides and demonstrate it with a selection of numerical experiments typical in the application area. …

Stability of Local Out-of-Plane Deformations of Orthotropic Sheet : Numerical Approach

2018

An evolutionary perspective on stress responses, damage and repair

2022

Variation in stress responses has been investigated in relation to environmental factors, species ecology, life history and fitness. Moreover, mechanistic studies have unravelled molecular mechanisms of how acute and chronic stress responses cause physiological impacts (‘damage’), and how this damage can be repaired. However, it is not yet understood how the fitness effects of damage and repair influence stress response evolution. Here we study the evolution of hormone levels as a function of stressor occurrence, damage and the efficiency of repair. We hypothesise that the evolution of stress responses depends on the fitness consequences of damage and the ability to repair that damage. To o…

K-kertaisesti kiellettyjen uniikkien β-siirtymien faasiavaruusintegraalit

2018

Tässä tutkimuksessa perehdytään K-kertaisesti kiellettyjen uniikkien beetasiirtymien faasiavaruusintegraaleihin. K-kertaisesti kielletyt uniikit beetasiirtymät ovat beetahajoamisten alaryhmä, ja faasiavaruusintegraalit kuvaavat hajoamisreaktion jälkeisiä lopputiloja ja antavat muun muassa tärkeää tietoa siirtymän hajoamisvakiosta. Tutkimuksessa laskettiin numeerisesti faasiavaruusintegraalit useille tunnetuille beetasiirtymille, jotka voivat olla kaksi- tai useampikertaisesti kiellettyjä. Saatua laskentadataa analysoitiin eri näkökulmista. Tärkein näkökulma on kielletyn uniikin beetasiirtymän ja samaa beetahajoamista kuvaavan perus- eli sallitun siirtymän välinen suhde, koska tämä näkökulma…

Rungen lause ja sovelluksia inversio-ongelmiin

2018

New insights on the role of ecology and life-history in social evolution

2017

Biological altruism, defined as a behaviour that benefits others at an apparent cost to the focal individual, is found abundantly across different levels of biological organization. While kin selection has been useful for explaining both cooperation and conflict in specialized cooperative societies, more theoretical work has to be done to develop models for realistic ecological and life-history contexts. This thesis aims to fill this gap by providing several new insights on the role of ecology and life-history in various social systems. Firstly, I propose a model that incorporates realistic ecological mechanisms of population regulation and study how different population regulation mechanisms affe…