Sökresultat

In this paper we study the application of boundary integral equation methods to the solution of the Helmholtz equation in a locally perturbed half-plane with Robin or impedance boundary conditions. This problem models outdoor noise propagation from a cutting onto a surrounding flat plane, and also the harbour resonance problem in coastal engineering. We employ Green's theorem to derive a system of

The asymptotic states of numerical methods for initial value problems are examined. In particular, spurious steady solutions, solutions with period 2 in the timestep, and spurious invariant curves are studied. A numerical method is considered as a dynamical system parameterised by the timestep h. It is shown that the three-kinds of spurious solutions can bifurcate from genuine steady solutions of

We consider second kind integral equations of the form x(s) - ʃΩ k(s, t)x(t) dt = y(s) (abbreviated x - Kx = y), in which Ω is some unbounded subset of Rn Let Xp denote the weighted space of functions x continuous on Ω and satisfying x(s) = O(|s| -p), s → ∞. We show that if the kernel k(s, t) decays like | s - t | -q as | s - t | → ∞ for some sufficiently large q (and some other mild conditions on

In this paper we present a semi-analytical model which enables the acoustic pressure field created by two spheres radiating close together to be predicted at any point outside the spheres. By representing the pressure field from each sphere as a finite sum of spherical harmonics and satisfying the boundary conditions at a finite number of points on the surface of each sphere, the problem reduces t

A spectral element method is described which enables reduced wave equation problems defined in regular, arbitrary length regions to be solved as a set of coupled problems over neighbouring domains. A combination of trial functions are considered, namely the specific eigenfunctions of a differential operator and a set of hierarchical polynomials. The coefficients in the representation of the acoust

A boundary integral equation is described for the prediction of acoustic propagation from a monofrequency coherent line source in a cutting with impedance boundary conditions onto surrounding Hat impedance ground. The problem is stated as a boundary value problem for the Helmholtz equation and is subsequently reformulated as a system of boundary integral equations via Green's theorem. The numerica

A super-spectral finite element method is developed for the study of acoustical wave propagation in nonuniform waveguides. The formulation is based on a finite-element approach using a mixture of high order element shape functions and wave solutions. The numerical method provides solutions to acoustic duct or fluid waveguide environments which may be divided into rectangular sectors. Examples of i

A measurement of event-shape variables in proton-proton collisions at large momentum transfer is presented using data collected at s = 13 TeV with the ATLAS detector at the Large Hadron Collider. Six event-shape variables calculated using hadronic jets are studied in inclusive multijet events using data corresponding to an integrated luminosity of 139 fb−1. Measurements are performed in bins of je

Research on children's literature mainly involves literary texts. This article focuses on the underresearched genre of information books, and analyses the Swedish translation of a French information book intended for children aged 4-7. The source and target texts are studied from a Hallidayan perspective by situating the texts in their respective contexts of situation and culture, and comparing th

Background Good nutrition is essential for individual health, a notion that is particularly true during pregnancy. We have used a nutrition index that measures the adequacy of one's diet relative to the unique nutritional needs of individuals due to, for example, their activity level, dietary restrictions, lifestyle and body size. The use of this personalised metric of dietary nutritiousness in th

MI, motivational interviewing, is a counseling method for increasing a person's motivation for behavior change with a large prevalence in social work. MI emphasizes building trusting social worker-client relationships and is presented as concrete and simple to follow. MI's benefit is limited by actual opportunities for change through poverty, the labor market and health. The article aims to criticMI, motivational interviewing, is a counseling method for increasing a person's motivation for behavior change with a large prevalence in social work. MI emphasizes building trusting social worker-client relationships and is presented as concrete and simple to follow. MI's benefit is limited by actual opportunities for change through poverty, the labor market and health. The article aims to critic

Residential buildings consume up to 40% of total global energy production annually. Making the residential and commercial buildings less energy dependent is essential in reduction of greenhouse gas affects. One type of such buildings are known as Net-Zero Energy Building (ZEB). This paper introduces a summary of scholar works, which have been executed in the last decade to achieve Net-ZEB by using

Recent years have seen a surge of interest in prefigurative politics, which refers to the political strategies that model a future society on a micro level and aim to instantiate radical social change in and through practice. While most previous studies have focused on defining the concept and categorizing various types of prefiguration, this paper contributes by investigating under what circumsta

Today’s ambition to adapt and individualize welfare delivery poses a challenge to human service organizations at the same time seeking to standardize clients, with consequences for street-level bureaucrats. In this article, the implementation of an instrument for standardized assessment of income support (IA) in Swedish social services is used to investigate what strategies street-level bureaucrat

Background: Metalworkers are said to have heavy exposure to metals, but the amount of released metal ions from alloys and deposition on the hands is unknown. Objective: To analyze nickel, cobalt, and chromium in vitro release to the artificial sweat from nails and wire made of different alloys, and to test metal deposition on the fingers of metalworkers. Material and Methods: Six different samples

This article publishes results from a study on how formal equality is “done” in 48 individual action plans for handling social assistance. We use a street-level perspective to understand how policy is ‘done’ to enhance equality for applicants of social assistance. The analysis is based on theory on street-level bureaucracy as well as concept of equality. Applicants‘ difficulties with an uncomprehe

Organo-metal-halide (OMH) perovskites form a new class of materials withperovskite crystal structure ABX3 where A is an organic molecule, B is lead (Pb)and X is a halide atom (I or Br). OMH perovskite semiconductors have been widely used in photovoltaics due to their very strong absorption of sun light, very suitable electrical properties, and the ease of preparation. Today the power conversion ef

Purpose: While big data creates business value, knowledge on how value is created remains limited and research is needed to discover big data’s value mechanism. The purpose of this paper is to explore value creation capabilities of big data through an alignment perspective. Design/methodology/approach: The paper is based on a single case study of a service division of a large Danish wind turbine g

Natural resources, especially energy resources, are often considered vital to the process of economic development, with the availability of coal considered central for the nineteenth century. Clearly, however, although coal might have spurred economic development, development might also have spurred the discovery and use of coal. To shed light on this, we suggest that the case of resource-poor Den

This paper investigates the effect of educational mismatch of R&D workers on firm's returns to innovation. R&D labour mismatch emerges when R&D workers have competencies different from those required by their occupation providing a contribution to innovation lower than in the case of perfect educational matching. By estimating a knowledge production function on data for 13 manufacturin