Transient state

Abstract: This paper proposes a control strategy of finite-control-set model predictive torque control (FCS-MPTC) with a deadbeat (DB) solution for permanent-magnet synchronous motor drives. By using a DB solution, the process of selection of the best switching vector is optimized. The predicted DB voltage sector consisting of the desired voltage vector (VV) avoids the complete enumeration for testing all feasible VVs, which relieves the big calculation effort of the traditional FCS-MPTC method. The proposed system is experimentally carried out both in the steady state and in the transient state.

Abstract: Recently Wang et al. carried out a laboratory experiment, where a Brownian particle was dragged through a fluid by a harmonic force with constant velocity of its center. This experiment confirmed a theoretically predicted work related integrated transient fluctuation theorem (ITFT), which gives an expression for the ratio for the probability to find positive or negative values for the fluctuations of the total work done on the system in a given time in a transient state. The corresponding integrated stationary state fluctuation theorem (ISSFT) was not observed. Using an overdamped Langevin equation and an arbitrary motion for the center of the harmonic force, all quantities of interest for these theorems and the corresponding nonintegrated ones (TFT and SSFT, respectively) are theoretically explicitly obtained in this paper. While the TFT and the ITFT are satisfied for all times, the SSFT and the ISSFT only hold asymptotically in time. Suggestions for further experiments with arbitrary velocity of the harmonic force and in which also the ISSFT could be observed, are given. In addition, a nontrivial long-time relation between the ITFT and the ISSFT was discovered, which could be observed experimentally, especially in the case of a resonant circular motion of the center of the harmonic force.

Abstract: An expression is presented for the difference between the pressure in a producing well and the average pressure of its drainage area. It has been pointed out that the Mathews-Brons-Hazebroek method works accurately in the transient state, although the assumption of steady state is used in the division into drainage areas. The present method relies more heavily on this assumption, and, in the transient state, becomes increasingly inaccurate for smaller production times. Identical results are obtained in the steady state, and in this region the present method may be preferred for its simplicity. Under complete water drive the pressure at any point tends to become constant. Drainage areas, defined in the usual sense, have very irregular shapes, each one having to be in contact with the advancing water front. In this case it is preferable to divide the reservoir as regularly as possible into what can be called associated reservoir areas allocated to the wells.