Kurt Jörnsten

Previously, mathematical programming models for an early evaluation of a petroleum field have been developed. Among these is a mixed integer programming model, that incorporates a reservoir simulation and an economic evaluation model. This model is formulated in order to answer questions related to where wells should be drilled in order to get the best total value from the field development. Motivated by the new technology in flexible platform systems, we make an extension of this model. In many cases, it is desirable to determine the value of a possibility to move a production platform. We develop a model to find when, if at all, the platform should be moved to another location on the field. We also present some experimental results illustrating the value of this feature.

The basic, reasonable hypothesis underlying this paper is that many individuals are comfortable with their current combination of job and residential location and have no intention of changing job location or moving from where they live. This causes autocorrelation in the time series of commuting flows and provides a rationale for introducing fixed components in the trip distribution model. The fixed components are assumed to be constant in time and separated from the observed trip distribution. We next consider the residuals and fit the model by a constrained entropy-maximization procedure. Based on commuting data from Stockholm County in Sweden, the fixed component spatial interaction model is demonstrated to lead to a substantial improvement in goodness of fit compared with conventional spatial interaction models. The identification of fixed components leads to significantly lower estimates of the distance deterrence parameter, and fixed components are further argued to be potentially useful in a prediction perspective. The distance deterrence parameter in the fixed component model reflects the spatial interaction of workers who are actually considering changes in their residential and/or job location. We also compare alternative measures of spatial separation and discuss differences in commuting behaviour by gender.

Recently Beltran-Royo et.al presented a semi-Lagrangean relaxation for the classical p-median location problem. The results obtained using the semi-Lagrangean relaxation framework approach were quite impressive. In this paper we use a reformulation of the p-median problem in order to start from a formulation more suitable for semi Lagrangean relaxation and analyse the new approach on examples from the OR library .

Based on the coauthorship networks of the Norwegian School of Economics (NHH) and the BI Norwegian Business School we present a comparative analysis in terms of structures, collaborations and publicationsThe paper uses partly or exclusively text and data from Belik, I. & Jörnsten, K. (2014, May) and Belik, I. & Jörnsten, K. (2014, July). The networks’ structures are based on the NHH and the BI faculties’ publications recognized by the ISI Web of Science for the period 1950 - Spring, 2014 for the currently employed faculty members as of Spring, 2014. The analyzed networks cover the publication activities of the NHH and the BI faculty members based on the data retrieved from ISI Web of Science in Spring, 2014.