@article{Schlosser2016, author = {Schlosser, Rainer}, title = {Stochastic dynamic pricing and advertising in isoelastic oligopoly models}, series = {European Journal of Operational Research}, volume = {259}, journal = {European Journal of Operational Research}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0377-2217}, doi = {10.1016/j.ejor.2016.11.021}, pages = {1144 -- 1155}, year = {2016}, abstract = {In this paper, we analyze stochastic dynamic pricing and advertising differential games in special oligopoly markets with constant price and advertising elasticity. We consider the sale of perishable as well as durable goods and include adoption effects in the demand. Based on a unique stochastic feedback Nash equilibrium, we derive closed-form solution formulas of the value functions and the optimal feedback policies of all competing firms. Efficient simulation techniques are used to evaluate optimally controlled sales processes over time. This way, the evolution of optimal controls as well as the firms' profit distributions are analyzed. Moreover, we are able to compare feedback solutions of the stochastic model with its deterministic counterpart. We show that the market power of the competing firms is exactly the same as in the deterministic version of the model. Further, we discover two fundamental effects that determine the relation between both models. First, the volatility in demand results in a decline of expected profits compared to the deterministic model. Second, we find that saturation effects in demand have an opposite character. We show that the second effect can be strong enough to either exactly balance or even overcompensate the first one. As a result we are able to identify cases in which feedback solutions of the deterministic model provide useful approximations of solutions of the stochastic model.}, language = {en} } @article{BuschmannTrappDoellner2016, author = {Buschmann, Stefan and Trapp, Matthias and D{\"o}llner, J{\"u}rgen Roland Friedrich}, title = {Animated visualization of spatial-temporal trajectory data for air-traffic analysis}, series = {The Visual Computer}, volume = {32}, journal = {The Visual Computer}, publisher = {Springer}, address = {New York}, issn = {0178-2789}, doi = {10.1007/s00371-015-1185-9}, pages = {371 -- 381}, year = {2016}, abstract = {With increasing numbers of flights worldwide and a continuing rise in airport traffic, air-traffic management is faced with a number of challenges. These include monitoring, reporting, planning, and problem analysis of past and current air traffic, e.g., to identify hotspots, minimize delays, or to optimize sector assignments to air-traffic controllers. To cope with these challenges, cyber worlds can be used for interactive visual analysis and analytical reasoning based on aircraft trajectory data. However, with growing data size and complexity, visualization requires high computational efficiency to process that data within real-time constraints. This paper presents a technique for real-time animated visualization of massive trajectory data. It enables (1) interactive spatio-temporal filtering, (2) generic mapping of trajectory attributes to geometric representations and appearance, and (3) real-time rendering within 3D virtual environments such as virtual 3D airport or 3D city models. Different visualization metaphors can be efficiently built upon this technique such as temporal focus+context, density maps, or overview+detail methods. As a general-purpose visualization technique, it can be applied to general 3D and 3+1D trajectory data, e.g., traffic movement data, geo-referenced networks, or spatio-temporal data, and it supports related visual analytics and data mining tasks within cyber worlds.}, language = {en} }