We discuss epistemological and methodological aspects of the Bayesian approach in astrophysics and cosmology. The introduction to the Bayesian framework is given for a further discussion concerning the Bayesian inference in physics. The interplay between the modern cosmology, Bayesian statistics, and philosophy of science is presented. We consider paradoxes of confi rmation, like Goodman’s paradox, appearing in the Bayesian theory of confirmation. As in Goodman’s paradox the Bayesian inference is susceptible to some epistemic limitations in the logic of induction. However, Goodman’s paradox applied to cosmological hypotheses seems to be resolved due to the evolutionary character of cosmology and the accumulation of new empirical evidence. We argue that the Bayesian framework is useful in the context of falsifiability of quantum cosmological models, as well as contemporary dark energy and dark matter problem.
The aim of this paper is to present a new approach to the problem of silicon integrated spiral inductors modeling. First, an overview of models and modeling techniques is presented. Based on 3D simulations and published measurement results, a list of physical phenomena to be taken into account in the model is created and based on it, the spiral inductor modeling by frequency sampling method is presented. To verify the proposed method a test circuit, containing 6 spiral inductors was designed and integrated in a silicon technology. The parameters of the spiral inductors from the test circuit were next measured and compared with simulations results. The comparison for one of those six spiral inductors is presented in the article.
An electric power steering system (EPS) is a new type of steering system developed after a mechanical hydraulic power system (MHPS) and electric-hydraulic power steering system (EHPS). In order to coordinate and solve the portability and sensitivity of the steering system optimally, taking an induction power steering system as the research object, the control algorithm of induction motor control under the EPS is studied in this paper. In order to eliminate the feed-forward performance degradation caused by the change of feed-forward parameters, an on-line identification algorithm of feed-forward parameters is proposed. It can improve the control performance of online identification among three feed-forward parameters in the T-axle motor, it improves on the robustness of feed-forward control performance, at the same time it also gives simulation and test results. This method can improve the control performance of the three feed-forward parameter online identification of the T-axis motor and improve the robustness of feed-forward control performance. At the same time, simulation and test results are given. The simulation results show that the algorithm can significantly improve the response speed and control accuracy of EPS system control.
Quality of electric current delivered to the magnets of a particle accelerator is essential for safety and reliability of its operation. Even small discrepancies strongly affect the properties of particle beams. One of the sources of the disturbances is the appearance of induced currents caused by the electromagnetic interactions between the elements of the machine. In this paper the calculations of induced currents in by-pass lines of a SIS100 particle accelerator are presented. In order to find the values of the currents the self-inductances and mutual inductances of the by-pass lines are found. Due to the complex geometry of the line, especially of Ω-shaped dilatations, the numerical approach was employed. The calculations show that the size of induced currents increases with the distance between the cables in an individual bus-bar. The maximum discrepancy of the magnetic field in a dipole magnet is found to be 7.7 μT. The decrease of distance between the cables allows one to obtain a discrepancy of 1.2 μT.
This paper presents active inductor based VCO design for wireless applications based on analysis of active inductor models (Weng-Kuo Cascode active inductor & Liang Regular Cascode active inductor) with feedback resistor technique. Embedment of feedback resistor results in the increment of inductance as well as the quality factor whereas the values are email@example.comGHz (Liang) and firstname.lastname@example.orgGHz (Weng-Kuo). The Weng-Kuo active inductor based VCO shows a tuning frequency of 1.765GHz ~2.430GHz (31.7%), while consuming a power of 2.60 mW and phase noise of -84.15 dBc/Hz@1MHz offset. On the other hand, Liang active inductor based VCO shows a frequency range of 1.897GHz ~2.522GHz (28.28%), while consuming a power of 1.40 mW and phase noise of -80.79 dBc/Hz@1MHz offset. Comparing Figure-of-Merit (FoM), power consumption, output power and stability in performance, designed active inductor based VCOs outperform with the stateof- the-art.
We present the development of a technique for studying laser-induced magnetization dynamics, based on inductive measurement. The technique could provide a simple tool for studying laser-induced demagnetization in thin films and associated processes, such as Gilbert damping and magnetization precession. It was successfully tested using a nanosecond laser and NiZn ferrite samples and – after further development – it is expected to be useful for observation of ultra-fast demagnetization. The combination of optical excitation and inductive measurement enables to study laser-induced magnetization dynamics in both thin and several micrometre thick films and might be the key to a new principle of ultrafast broadband UV–IR pulse detection.
This paper deals with the modelling of traction linear induction motors (LIMs) for public transportation. The magnetic end effect inherent to these motors causes an asymmetry of their phase impedances. Thus, if the LIM is supplied from the three-phase symmetrical voltage, its phase currents become asymmetric. This effect must be taken into consideration when simulating the LIMs’ performance. Otherwise, when the motor phase currents are assumed to be symmetric in the simulation, the simulation results are in error. This paper investigates the LIM performance, considering the end-effect induced asymmetry of the phase currents, and presents a comparative study of the LIM performance characteristics in both the voltage and the current mode.
This paper investigates the application of a novel Model Predictive Control structure for the drive system with an induction motor. The proposed controller has a cascade-free structure that consists of a vector of electromagnetics (torque, flux) and mechanical (speed) states of the system. The long-horizon version of the MPC is investigated in the paper. In order to reduce the computational complexity of the algorithm, an explicit version is applied. The influence of different factors (length of the control and predictive horizon, values of weights) on the performance of the drive system is investigated. The effectiveness of the proposed approach is validated by some experimental tests.
In this paper a scaling approach for the solution of 2D FE models of electric machines is proposed. This allows a geometrical and stator and rotor resistance scaling as well as a rewinding of a squirrel cage induction machine enabling an efficient numerical optimization. The 2D FEM solutions of a reference machine are calculated by a model based hybrid numeric induction machine simulation approach. In contrast to already known scaling procedures for synchronous machines the FEM solutions of the induction machine are scaled in the stator-current-rotor-frequency-plane and then transformed to the torque- speed-map. This gives the possibility to use a new time scaling factor that is necessary to keep a constant field distribution. The scaling procedure is validated by the finite element method and used in a numerical optimization process for the sizing of an electric vehicle traction drive considering the gear ratio. The results show that the scaling procedure is very accurate, computational very efficient and suitable for the use in machine design optimization.