933 research outputs found

    User Participation in Consulting Projects: Client and Provider Role Variations

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    This study presents a variation scheme of participation roles in consulting projects. Typical consulting assignments in the area known as IS planning involve strategic planning and information systems management, enterprise architecture, information management or information technology governance. Participation is a crucial issue in consulting on these issues. In the literature on participation, different roles and tasks have been found, but it is not always specified, on what types of projects or systems the results are based. The literature on consulting suggests some models for work division. In a two-phase qualitative study, we first collect possible tasks in ICT consulting projects, and then, based on further explorations, create a model for role variations in consulting. We compare roles suggested in the literature on participation and on consulting to our findings. The suggested variation model gives a common framework of reference for negotiations between the provider and the client, and helps to anticipate the needed competences and resources from both parties, and discern between their responsibilities

    An Overview of Science Challenges Pertaining to our Understanding of Extreme Geomagnetically Induced Currents

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    Vulnerability of man-made infrastructure to Earth-directed space weather events is a serious concern for today's technology-dependent society. Space weather-driven geomagnetically induced currents (GICs) can disrupt operation of extended electrically conducting technological systems. The threat of adverse impacts on critical technological infrastructure, like power grids, oil and gas pipelines, and communication networks, has sparked renewed interest in extreme space weather. Because extreme space weather events have low occurrence rate but potentially high impact, this presents a major challenge for our understanding of extreme GIC activity. In this chapter, we discuss some of the key science challenges pertaining to our understanding of extreme events. In addition, we present an overview of GICs including highlights of severe impacts over the last 80 years and recent U.S. Federal actions relevant to this community

    Perturbation Monte Carlo Method for Quantitative Photoacoustic Tomography

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    Quantitative photoacoustic tomography aims at estimating optical parameters from photoacoustic images that are formed utilizing the photoacoustic effect caused by the absorption of an externally introduced light pulse. This optical parameter estimation is an ill-posed inverse problem, and thus it is sensitive to measurement and modeling errors. In this work, we propose a novel way to solve the inverse problem of quantitative photoacoustic tomography based on the perturbation Monte Carlo method. Monte Carlo method for light propagation is a stochastic approach for simulating photon trajectories in a medium with scattering particles. It is widely accepted as an accurate method to simulate light propagation in tissues. Furthermore, it is numerically robust and easy to implement. Perturbation Monte Carlo maintains this robustness and enables forming gradients for the solution of the inverse problem. We validate the method and apply it in the framework of Bayesian inverse problems. The simulations show that the perturbation Monte Carlo method can be used to estimate spatial distributions of both absorption and scattering parameters simultaneously. These estimates are qualitatively good and quantitatively accurate also in parameter scales that are realistic for biological tissues
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