47 research outputs found
Sparse Identification of Nonlinear Duffing Oscillator From Measurement Data
In this paper we aim to apply an adaptation of the recently developed
technique of sparse identification of nonlinear dynamical systems on a Duffing
experimental setup with cubic feedback of the output. The Duffing oscillator
described by nonlinear differential equation which demonstrates chaotic
behavior and bifurcations, has received considerable attention in recent years
as it arises in many real-world engineering applications. Therefore its
identification is of interest for numerous practical problems. To adopt the
existing identification method to this application, the optimization process
which identifies the most important terms of the model has been modified. In
addition, the impact of changing the amount of regularization parameter on the
mean square error of the fit has been studied. Selection of the true model is
done via balancing complexity and accuracy using Pareto front analysis. This
study provides considerable insight into the employment of sparse
identification method on the real-world setups and the results show that the
developed algorithm is capable of finding the true nonlinear model of the
considered application including a nonlinear friction term.Comment: 6 pages, 8 figures, conference pape
Copper Gate MOS Capacitors Utilizing Chemical-Mechanical Planarization
Applying chemical mechanical planarization techniques to form the gate for a Cu/Ti/SiO2/Si capacitor stack has shown to be a viable alternative to conventional etching techniques used in the fabrication of MOS devices. Furthermore, it is reported that CMP does not compromise the integrity of the dielectric nor does it have an adverse affect on device performance
Identification of Synchronous Machine Magnetization Characteristics From Calorimetric Core-Loss and No-Load Curve Measurements
The magnetic material characteristics of a wound-field synchronous machine are identified based on global calorimetric core-loss and no-load curve measurements. This is accomplished by solving a coupled experimental-numerical electromagnetic inverse problem, formulated to minimize the difference between a finite-element (FE) simulation-based Kriging surrogate model and the measurement results. The core-loss estimation in the FE model is based on combining a dynamic iron-loss model and a static vector Jiles-Atherton hysteresis model, the parameters for which are obtained by solving the inverse problem. The results show that reasonable hysteresis loops can be produced for a grid-supplied machine, while for an inverter-supplied machine the limitations in the FE and iron-loss models seemingly exaggerate the area of the loop. In addition, the effect of the measurement uncertainty on the inverse problem is quantitatively estimated.Peer reviewe
Effect of Multilevel Inverter Supply on Core Losses in Magnetic Materials and Electrical Machines
The effect of multilevel inverter supply on power losses in magnetic cores and electrical machines is studied. A dynamic numerical model for the hysteresis, eddy current, and excess losses in a core lamination is first developed. By both measurements and simulations for a ring-core inductor, we demonstrate how increasing the number of inverter voltage levels decreases the iron losses when compared with traditional two-level supply. Although the switching frequency has a significant impact on the iron losses in the case of a traditional two-level inverter, using three or five voltage levels makes the losses almost independent of the switching. Finally, finite-element simulations show that simi-lar reductions are also possible for the core losses of 150-kVA and 12.5-MW wound-field synchronous machines, in which rather low switching frequencies are typically used. Calorimetric loss measurements are also presented for the 150-kVA machine in order to confirm the significant effect of switching frequency on the core losses with two-level inverter supply.Peer reviewe