Search results for "Boundary"

Strictly convergent algorithm for an elliptic equation with nonlocal and nonlinear boundary conditions

2012

The paper describes a formally strictly convergent algorithm for solving a class of elliptic problems with nonlinear and nonlocal boundary conditions, which arise in modeling of the steady-state conductive-radiative heat transfer processes. The proposed algorithm has two levels of iterations, where inner iterations by means of the damped Newton method solve an appropriate elliptic problem with nonlinear, but local boundary conditions, and outer iterations deal with nonlocal terms in boundary conditions.

Lower bound limit analysis by bem: Convex optimization problem and incremental approach

2013

Abstract The lower bound limit approach of the classical plasticity theory is rephrased using the Multidomain Symmetric Galerkin Boundary Element Method, under conditions of plane and initial strains, ideal plasticity and associated flow rule. The new formulation couples a multidomain procedure with nonlinear programming techniques and defines the self-equilibrium stress field by an equation involving all the substructures (bem-elements) of the discretized system. The analysis is performed in a canonical form as a convex optimization problem with quadratic constraints, in terms of discrete variables, and implemented using the Karnak.sGbem code coupled with the optimization toolbox by MatLab…

The work-family interface and its correlates : integrating variable and person oriented approaches

2017

The aim of this research was to examine key correlates of the interaction between work and family in one Nordic country, Finland, using a person- oriented and variable-oriented approach. The correlates that were chosen and examined over the course of three studies were job control and work-family boundary management styles, turnover intention, core self-evaluations, and vigor at work. Study I was part of a 2-year longitudinal study which was conducted in two Finnish universities (n = 700); Study II consisted of two samples, one of university employees (University 1, n = 666; University 2, n = 644), and the other of nurses (n = 301) from one healthcare district in Finland; and Study III used…

Monitoring water and carbon fluxes at fine spatial scales using HyspIRI-like measurements

2012

Remotely sensed observations in the visible to the shortwave infrared (VSWIR) and thermal infrared (TIR) regions of the electromagnetic spectrum can be used synergistically to provide valuable products of land surface properties for reliable assessments of carbon and water fluxes. The high spatial, spectral and temporal resolution VSWIR and TIR observations provided by the proposed Hyperspectral - InfraRed (HyspIRI) mission will enable a new era of global agricultural monitoring, critical for addressing growing issues of food insecurity. To enable predictions at fine spatial resolution (<100m), modeling efforts must rely on a combination of high-frequency temporal and highresolution spa…

The Billiemi breccia: the record of Rhaetian/lowermost Jurassic brittle deformations along the Panormide shelf edge

2010

The academic identity and boundaries of the discipline of social work : reflections of social work professors on the recruitment and research of doct…

2019

Finland has a strong and long tradition of research-oriented doctoral education in social work. Recent general changes in doctoral education, such as increased regulation, internationalisation and time pressures, have had an impact on social work as an academic discipline. This article examines the recruitment of social work doctoral students and the perceived value of doctoral dissertations as academic research. The data consist of written responses by Finnish full professors of social work to open-ended questions presented in an electronic questionnaire. The analysis is based on the idea of ‘boundary work’ within and between disciplines, and between science and society and on the professo…

Stieltjes Differential Inclusions with Periodic Boundary Conditions without Upper Semicontinuity

2021

We are studying first order differential inclusions with periodic boundary conditions where the Stieltjes derivative with respect to a left-continuous non-decreasing function replaces the classical derivative. The involved set-valued mapping is not assumed to have compact and convex values, nor to be upper semicontinuous concerning the second argument everywhere, as in other related works. A condition involving the contingent derivative relative to the non-decreasing function (recently introduced and applied to initial value problems by R.L. Pouso, I.M. Marquez Albes, and J. Rodriguez-Lopez) is imposed on the set where the upper semicontinuity and the assumption to have compact convex value…

Age-Structured Human Population Dynamics

2006

ABSTRACT A von Foerster-McKendrick model to study age-structured human population dynamics is presented in this paper. Forecasts of population density (population per age unit) depending on ages are possible using this model. The model consists of a quasi-linear first order partial differential equation for the dynamics of population density per age-unit (except for the zero-age), a boundary condition for the births flow at zero-age, and an initial condition for the population density at the initial instant. A general solution independent of the particular human-system under study is obtained based on some hypotheses about the mathematical structure of its input variables. The model has bee…

Existence and uniqueness results for a nonlinear evolution equation arising in growing cell populations

2014

Abstract The present paper is concerned with a nonlinear initial–boundary value problem derived from a model introduced by Rotenberg (1983) describing the growth of a cell population. Each cell of this population is distinguished by two parameters: its degree of maturity μ and its maturation velocity v . At mitosis, the daughter cells and mother cells are related by a general reproduction rule. We prove existence and uniqueness results in the case where the total cross-section and the boundary conditions are depending on the total density of population. Local and nonlocal reproduction rules are discussed.

An existence and uniqueness principle for a nonlinear version of the Lebowitz-Rubinow model with infinite maximum cycle length

2017

The present article deals with existence and uniqueness results for a nonlinear evolution initial-boundary value problem, which originates in an age-structured cell population model introduced by Lebowitz and Rubinow (1974) describing the growth of a cell population. Cells of this population are distinguished by age a and cycle length l. In our framework, daughter and mother cells are related by a general reproduction rule that covers all known biological ones. In this paper, the cycle length l is allowed to be infinite. This hypothesis introduces some mathematical difficulties. We consider both local and nonlocal boundary conditions.