Search results for "Aerospace engineering"

Road to unity? : Nordic economic convergence in the long run

2022

This study examines Nordic economic convergence from the sixteenth to twentieth century respective of the economic leaders, in effect the UK before 1914 and USA thereafter. The paper uses a novel approach of combining the analysis of both GDP and wages. The examination of real GDP per capita suggests that there was a catch-up process in play, both with the economic leaders and among the Nordic states, from the early nineteenth century onwards. However, the examination of the adjusted silver wages suggests convergence among the Nordic economies by the end of the eighteenth century. Therefore, we argue, no single Nordic Model emerged from these development patterns, even though the Nordic sta…

Defending dissertations on economic history

2016

In most disciplines, the number, quality and topics of doctoral dissertations afford useful information on the state of affairs in research and formal graduate education. Moreover, dissertations ma...

Towards debate and open conversation

2016

Unequal poverty and equal industrialisation: Finnish wealth, 1750–1900

2018

We present the first comprehensive, long-run estimates of Finnish wealth and its distribution from 1750 to 1900. Using wealth data from 17,279 probate inventories, we show that Finland was very unequal between 1750 and 1850; the top decile owned about 90% of total wealth. This means that Finland was more unequal than the much wealthier economies Britain, France and the US, which goes against the common assumption of richer economies being more unequal. Moreover, when industrialisation took off in Finland, inequality started a downward trajectory. High inequality 1750–1850 was bottom-driven, by a large share of the population owning nothing or close to nothing of value, while economic develo…

A New Procedure for the Evaluation of Non-Uniform Residual Stresses by the Hole Drilling Method Based on the Newton-Raphson Technique

2010

The hole drilling method is one of the most used semi-destructive techniques for the analysis of residual stresses in mechanical components. The non-uniform stresses are evaluated by solving an integral equation in which the strains relieved by drilling a hole are introduced. In this paper a new calculation procedure, based on the Newton-Raphson method for the determination of zeroes of functions, is presented. This technique allows the user to introduce complex and effective forms of stress functions for the solution of the problem. All the relationships needed for the evaluation of the stresses are obtained in explicit form, eliminating the need to use additional mathematical tools. The t…

Measurement of residual stresses by the hole-drilling method: General stress-strain relationship and its solution

1990

RESIDUAL STRESS ANALYSIS OF ORTHOTROPIC MATERIALS BY THE THROUGH-HOLE DRILLING METHOD

2007

The present study deals with the development and the application of the through-hole drilling method for the residual stress analysis in orthotropic materials. Through a systematic theoretical study of the stress field present on orthotropic plates with a circular hole, the relationships between the relaxed strains measured by a rectangular strain gauge rosette and the Cartesian components of the unknown residual stresses are obtained. The theoretical formulas of each influence coefficient allow the user an easy application of the method to the analysis of uniform-residual stresses on a generic homogeneous orthotropic material. Furthermore, to extend the method to the analysis of the residu…

Optimal calculation steps for the evaluation of residual stress by the incremental hole-drilling method

1999

The integral method is a suitable calculation procedure for the determination of nonuniform residual stresses by semidestructive mechanical methods such as the hole-drilling method and the ring-core method. However, the high sensitivity to strain measurement errors due to the ill conditioning of the equations has hindered its practical use. the analysis of the influence of the strain measurment error on the computed stresses carried out in the present work has showed that, given both maximum hole depth and number of total steps, the error sensitivity depends on the particular depth increment distribution used. By means of the matrix formulation, the depth increment distribution that optimiz…

Convergent Analytic Solutions for Homoclinic Orbits in Reversible and Non-reversible Systems

2013

In this paper, convergent, multi-infinite, series solutions are derived for the homoclinic orbits of a canonical fourth-order ODE system, in both reversible and non-reversible cases. This ODE includes traveling-wave reductions of many important nonlinear PDEs or PDE systems, for which these analytical solutions would correspond to regular or localized pulses of the PDE. As such, the homoclinic solutions derived here are clearly topical, and they are shown to match closely to earlier results obtained by homoclinic numerical shooting. In addition, the results for the non-reversible case go beyond those that have been typically considered in analyses conducted within bifurcation-theoretic sett…

Modified post-bifurcation dynamics and routes to chaos from double-Hopf bifurcations in a hyperchaotic system

2012

In order to understand the onset of hyperchaotic behavior recently observed in many systems, we study bifurcations in the modified Chen system leading from simple dynamics into chaotic regimes. In particular, we demonstrate that the existence of only one fixed point of the system in all regions of parameter space implies that this simple point attractor may only be destabilized via a Hopf or double Hopf bifurcation as system parameters are varied. Saddle-node, transcritical and pitchfork bifurcations are precluded. The normal form immediately following double Hopf bifurcations is constructed analytically by the method of multiple scales. Analysis of this generalized double Hopf normal form …