Effect of parameters on back-EMF in permanent magnet brushless DC motor with concentrated winding
A method for analyzing the concentrated windings back-EMF in permanent magnet brushless DC motor, based on the analytical calculation of one phase back-EMF by using Fourier series, has been developed and validated by comparing computing waves to measured waveforms. And the paper discussed the influence on back-EMF of design parameters.
Magnetic equivalent circuit model of surface type fractional-slot permanent magnet synchronous generator
Design of permanent magnet synchronous machines becomes more of an issue for all systems lately. There are many parameters that have influence for machine design. Each parameter should have optimized and their effects on the system should be determined. Any desired pre-design have been done for machine design except a few paper and it only showed by of Finite element analysis (FEA). In this article, analytical method is used in permanent magnet synchronous machine design and the effects of geometric on the performance of machine are presented. Magnetic equivalent circuit (MEC) model is used as numeric method. It is observed that the proposed MEC model is pertinent to Speed PC-BDC model and FEA. Besides proposed MEC model provides to calculate performances of the machines which have the desirable slot/pole combinations correctly. Proposed model is applied on the recently increased fractional slot direct drive synchronous generators.
Pig Vocalizations Under Selected Husbandry Practices
Acoustical characteristics of vocalizations of sows, piglets, and nursery pigs under selected husbandry practices were analyzed with a digital signal processing system. The duration (D) and major energy-resonance frequency (P) for each call were determined as follows: a) processing of piglets (D = 0.81 s and f* = 3 700 Hz); b) food anticipation of breeding-gest ation sows (2.50 s and 3 000 Hz); c) isolation of piglet (0.34 s and 500, 3 500 Hz); d) startling of nursery pigs (0.29 s and 900 Hz); e) sows in heat (3.07 s and 1 375 Hz); f) farrowing (0.10 s and 3 000 Hz); g) sow nursing (0.15 s and 1 000 Hz); and h) mate greeting of sow (0.13 s and 1 000 Hz). Calls a) to d) are responses to human generated stressors, and calls e) through h) responses to social and physiological states of the pigs. Thus, vocalizations can be segmented for different pig production situations.