In this paper, a new loss minimization control algorithm for inverter-fed permanent-magnet synchronous motors (PMSMs), which allows for the reduction of the power losses of the electric drive without penalty on its dynamic performance, is analyzed, experimentally realized, and validated. In particular, after a brief recounting of two loss minimization control strategies, namely, the "search control" and the "loss-model control," both a new modified dynamic model of the PMSM (which takes into account the iron losses) and an innovative "loss-model" control strategy are presented. Experimental tests on a specific PMSM drive employing the proposed loss minimization algorithm have been performed, aiming to validate the actual implementation. The main results of these tests confirm that the dynamic performance of the drive is maintained, and in small motors enhancement up to 3.5% of the efficiency can be reached in comparison with the PMSM drive equipped with a more traditional control strategy. Index Terms-Control systems, efficiency improvement, permanent-magnet synchronous motor (PMSM), variable-speed motor drives. NOMENCLATURE , Direct-and quadrature-axes current components. , Direct-and quadrature-axes iron loss current components. , Direct-and quadrature-axes voltage components. , Direct-and quadrature-axes inductances. , Direct-and quadrature-axes leakage inductances. , Direct-and quadrature-axes magnetizing inductances Magnetic saliency ratio. , Stator and core loss resistances. Permanent-magnet rotor flux. Motor pole pairs. Angular electrical frequency. Rotor mechanical angular speed. Electromagnetic torque. Load torque.

SYNOPSISTime-resolved studies of network self-organization from homogeneous solutions of the representative biostructural polymer agarose are presented. Solutions are temperature quenched and observed by several techniques. Consistent with previous suggestions by the authors, experiments at concentrations up to about 1.75% w/v provide direct kinetic evidence for the occurrence of at least two distinct processes, leading, in sequence, to selfassembly. These are as follows: ( a ) a liquid-liquid phase separation of the solution occurring via spinodal demixing and resulting in two sets of regions that have, respectively, higher and lower than average concentrations of random-coiled polymers; and ( b ) the subsequent 2 coils + double helix transition and accompanying cross-linking and gelation (due to branching of double helices ), occurring in the high-concentration regions. The size of the high-concentration regions depends upon agarose concentration and quenching temperature, and is in the range from a fraction of micrometers to a few micrometers, in agreement with earlier experiments. Bundling of the double-helical segments is known to follow self-assembly and can be considered as a third step (gel curing). This follows from the thermodynamic instability of the helical segments in the solvent, behaving as a system of rod-like particles connected by more or less flexible joints.The two processes leading in succession to self-assembly are discussed in terms of a phase diagram consistent with available data. Their time scales differ remarkably. A t the end of the first process, all polymers remain random coiled and freely drifting. Much later coil-helix transition is observed, always in coincidence with polymer cross-linking and gelation. The enhancement of concentration of random-coiled polymers in specific regions of the sol caused by spinodal demixing is thus a prerequisite for self-assembly of these biostructural gels in the concentration interval studied. Conceptually, concentration enhancements of this type can provide a new pathway for promotion of functional biomolecular interactions even at very low average concentrations. The mechanism will work identically if the region of instability is reached by varying the polymer concentration (e.g., by biosynthesis), rather than by temperature quenching.

We investigate the stochastic resonance phenomenon in a physical system based on a tunnel diode. The experimental control parameters are set to allow the control of the frequency and amplitude of the deterministic modulating signal over an interval of values spanning several orders of magnitude. We observe both a regime described by the linear response theory and the nonlinear deviation from it. In the nonlinear regime we detect saturation of the power spectral density of the output signal detected at the frequency of the modulating signal and a dip in the noise level of the same spectral density. When these effects are observed we detect a phase and frequency synchronization between the stochastic output and the deterministic input. 85.30.Mn

In this paper Noise Enhanced Stability in magnetic systems is studied by both an Ising like model and a Preisach Arrhenius model as well as a Dynamic Preisach Model. It is shown that in one non equilibrium Ising systems Noise Enhanced Stability occurs and that Dynamic Preisach Model has the capability to predict the occurrence of NES in magnetic systems. On the contrary, in a Preisach Arhhenius model of a single quadrant magnetic material NES is not detected