The MIIS Eprints Archive: No conditions. Results ordered -Date Deposited. 2019-04-23T10:12:21ZEPrintshttp://www.maths-in-industry.org/images/sitelogo.gifhttp://www.maths-in-industry.org/miis/2012-10-29T16:50:47Z2015-05-29T20:13:14Zhttp://www.maths-in-industry.org/miis/id/eprint/597This item is in the repository with the URL: http://www.maths-in-industry.org/miis/id/eprint/5972012-10-29T16:50:47ZDHV water pumping optimizationhis contribution investigates the possibilities for optimizing a drinking water network over a horizon of 48 hours, given variable water demands, energy prices and constraints on the pumping strategy and water levels in the reservoirs. Both the dynamic model and goal function are non-linear in the control inputs, the pump flow rates. Since each pump can be switched on or off every 15 minutes and since there are 15 pumps in the system, for a horizon of 48 hours there are 2(4×48×15) switching possibilities. Obviously, this problem is too big to solve it in real-time by enumeration. Hence, a decomposition of the problem is needed. Relaxing the constraints and assuming a continuous-time flow rate, allows a (semi)-analytical solution using Lagrangian theory. Furthermore, a numerical solution of the constrained optimization problem is found by using the TomLab PROMPT toolbox. The conversion from a continuous-time pump flow rate to a strategy with on/off switching is also investigated, as well as the possibility of linear feedback control. The resulting trajectories of the pump flow rates and water levels in the reservoirs are realistic and can be physically interpreted.S van MourikJ BierkensH Stigter2012-10-29T16:48:44Z2015-05-29T20:13:10Zhttp://www.maths-in-industry.org/miis/id/eprint/596This item is in the repository with the URL: http://www.maths-in-industry.org/miis/id/eprint/5962012-10-29T16:48:44ZStiffening while dryingWe present two models for the drying of waterborne paints, which consist of non-volatile latex particles suspended in water. One model considers the water and latex density in a layer as a function of time. Water evaporation at the surface represents the drying. This model results in a one-dimensional free boundary problem, which is solved numerically. Extensions to the model are given that describe the stiffening of the paint. A second model is a particle based dynamical simulation where latex particles form a network through which water particles move. A thin slab of the suspension in a three-dimensional box is studied. Water particles escaping the slab at the surface represent the drying, progressing network formation the stiffening of the paint. Both models allow for validation with material properties as determined experimentally on real coatings.F van BeckumJ Bouwe van den BergS Boettche2012-10-29T16:46:17Z2015-05-29T20:13:06Zhttp://www.maths-in-industry.org/miis/id/eprint/595This item is in the repository with the URL: http://www.maths-in-industry.org/miis/id/eprint/5952012-10-29T16:46:17ZApproximate solution to a hybrid model with stochastic volatility: a singular-perturbation strategyWe study a hybrid model of Schobel-Zhu-Hull-White-type from a singular-perturbation-analysis perspective. The merit of the paper is twofold: On one hand, we find boundary conditions for the deterministic non-linear degenerate parabolic partial differential equation for the evolution of the stock price. On the other hand, we combine two-scales regular- and singular-perturbation techniques to find an approximate solution to the pricing PDE. The aim is to produce an expression that can be evaluated numerically very fast.T FatimaL GrzelakH Hendriks2012-10-29T16:43:22Z2015-05-29T20:13:02Zhttp://www.maths-in-industry.org/miis/id/eprint/594This item is in the repository with the URL: http://www.maths-in-industry.org/miis/id/eprint/5942012-10-29T16:43:22ZHow to Mix Molecules with MathematicsIn this paper we develop two methods to calculate thermodynamic properties of mixtures. Starting point are the basic assumptions that also form the basis for the COSMO-RS model. In this approach, the individual molecules are represented by their geometrical shape with an electrical charge density on their surfaces. Next, the surface is split up into surface segments each with its own charge. In COSMO-RS a strong reduction is introduced by treating the segments as if they are completely independent. In the present study we take into account that the coupling between two patches is essentially dependent on the charge distribution on neighboring segments and on the local geometrical structure of the surface. Two approaches are followed. The first one points out how the model
equations, which comprise the optimization of the entropy and conservation of internal energy, can efficiently be solved in general, thus also if the dependency between segments and the local geometry is included in the expression for the coupling energy between segments. In the second method the configuration with maximal entropy and prescribed energy is sought via simulation. Successive molecular configurations of the mixture are simulated and updated via a genetic algorithm to optimize the entropy. The second method is more time consuming but very general.B van’t HofJ MolenaarL RosM Zaal2012-10-29T16:40:32Z2015-05-29T20:12:58Zhttp://www.maths-in-industry.org/miis/id/eprint/593This item is in the repository with the URL: http://www.maths-in-industry.org/miis/id/eprint/5932012-10-29T16:40:32ZAn objective method to associate local weather extremes with characteristic circulation structuresIn this paper we give methods to find characteristic circulation patterns which are connected to local extreme temperature anomalies. Two data reduction techniques are applied: Legendre polynomial fitting and watershedding. For polynomial fitting a clear trend is found with respect to local temperatures. However, the trend is not distinctive enough to give clear answers on the type of circulation patterns belonging to local extremes. The main advantage of watershedding is that the physical properties of the circulation patterns are retained while the dimension of the data is largely reduced. Expert knowledge, however, is needed to model these main features as predictors.C ZiemerK MarczyskaA Szczepanska2012-10-29T16:36:09Z2015-05-29T20:12:55Zhttp://www.maths-in-industry.org/miis/id/eprint/592This item is in the repository with the URL: http://www.maths-in-industry.org/miis/id/eprint/5922012-10-29T16:36:09ZDynamical Models of Extreme Rolling of Vessels in Head WavesRolling of a ship is a swinging motion around its length axis. In particular vessels transporting containers may show large amplitude roll when sailing in seas with large head waves. The dynamics of the ship is such that rolling interacts with heave being the motion of the mass point of the ship in vertical direction. Due to the shape of the hull of the vessel its heave is influenced considerably by the phase of the wave as it passes the ship. The interaction of heave and roll can be modeled by a mass-spring-pendulum system. The effect of waves is then included in the system by a periodic forcing term. In first instance the damping of the spring can be taken infinitely large making the system a pendulum with an in vertical direction periodically moving suspension. For a small angular deflection the roll motion is then described by the Mathieu equation containing a periodic forcing. If the period of the solution of the equation without forcing is about twice the period of the forcing then the oscillation gets unstable and the amplitude starts to grow. After describing this model we turn to situation that the ship is not anymore statically fixed at the fluctuating water level. It may move up and down showing a motion
modeled by a damped spring. One step further we also allow for pitch, a swinging motion around a horizontal axis perpendicular to the ship. It is recommended to investigate the way waves may directly drive this mode and to determine the amount of energy that flows along this path towards the roll mode. Since at sea waves are a superposition of waves with different wavelengths, we also pay attention to the properties of such a type of forcing containing stochastic elements. It is recommended that as a measure for the
occurrence of large deflections of the roll angle one should take the expected time for which a given large deflection may occur instead of the mean amplitude of the deflection.C ArcherE van DaalenS Dobbersch ̈tz