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• Investigation of the Resistance Force Acting on a Sailing Craft in the Case of a Change of Draft Caused by a Change of Powertrain Using Numerical CFD Simulations

  30-35

  Péter Ficzere

  Emese Lévai

  Views:

  201

  Nowdays In the case of recreational craft, interfering with motor drive solutions is a common workflow due to increasingly strict rules for environmental reasons. When switching from an internal combustion engine to an electric engine, the change in draft varies from boat to boat, but it can be said in all cases that as the mass changes, so does the draft. Because of this, the magnitude of the resistance force acting on the ship also varies. In this paper, we examine, through a specific example, the benefits of a change in dive caused by weight gain at different travel speeds.

• Global Inversion of Pressure Dependent Acoustic Velocity Data Based on a New Rock Physical Model

  47-55

  Judit Somogyiné Molnár

  Tünde Edit Dobróka

  Views:

  115

  In this paper with the further development of our previously published single exponential model, the new multiple exponential model describing the pressure dependence of acoustic longitudinal wave velocity is presented. Since with increasing pressure in the rock several relaxation mechanisms at the same time can cause the increasing propagation velocity, the new model can handle two or more physical mechanisms (e.g. the closure of pore volume or microcracks or friction on grain boundaries etc.). The previously applied linearized inversion procedure can trap in a local minimum, so during laboratory measured longitudinal velocity-pressure data processing a global optimization method was used to find the absolute minimum. Using the developed model equation as response equation in a Simulated Annealing algorithm the petrophysical parameters of the model can be determined. Inversion results proved that the calculated data using the new model and algorithm matched more accurate with measured data on a rock sample.