1,721,304 research outputs found
DC networks including multi-port DC/DC converters: Fault analysis
No full textDC networks that include storage systems, renewable sources, dc loads, and front-end converters can provide some advantages as compared with ac grids. However, the interruption of fault currents is difficult due to no-zero crossing of the current. Moreover, the fault clearing time of traditional dc circuit breakers can be too long for protecting power electronics switching components. Multiport converters seem to be a good solution for solving the aforementioned problem. The introduction of a multiport dc/dc converter, along with its configuration and a centralized control for power flow management, is proposed in the initial sections of this study. After this, this paper focuses on the study of system behavior during fault functioning conditions. Both pole-to-pole and pole-to-ground faults are investigated. The authors propose some control strategies and hardware solutions to overcome dc protection issues during several fault types. Some numerical simulation results are provided
the asymptotic behaviour of a proliferant-quiescent cell system
No full textThe authors study an age-structured model for the growth of cell populations. Their model accounts for the transition between different phases in the cell cycle and for transitions between proliferating and quiescent stages. In quiescence the maturation stops. Reproduction is assumed to occur via mitosis. The authors show the existence and the exponential stability of a stationary normalized age-distribution. This stationary normalized age-distribution corresponds to an exponentially growing solution of the cell-population model, where all components grow at the same rate. This rate, and the rate of convergence towards it, are derived from the model parameters. For the proof of stability the authors use Laplace transform methods, since the method of characteristics is not applicable
- …
