Publish in OALib Journal
APC: Only $99
The dynamical processes of the interaction of slow wind
beyond Red Giant phase with fast wind of central star of nebula are evaluated.
The mechanism of interaction stellar wind model (ISW) is found to be
responsible for producing a relatively dense shell of gas which increases in mass
and radius at a constant rate. Both slow wind and superwind are assumed to be
time independent and radial density is calculated at initial time to ~ 60 yrs with the
fast wind velocity (v ≈ 1000
km/s). The results showed that, at the outer rim of super wind region, a
small density hump appears due to the relative velocity between slow winds and
central star winds, in a good agreement with the previous models. The dynamical
requirements of the observed expansion of planetary nebulae can be satisfied by
the mechanism of interacting stellar wind model with reasonable mass loss rate
from central star.
Planetary Nebulae (PN)
distances represent the fundamental parameter for the determination the
physical properties of the central star of PN. In this paper the distances
scale to Planetary Nebulae in the Galactic bulge were calculated related
to previous distances scales. The proposed distance scale was done by
recalibrated the previous distance scale technique CKS/D82. This scale limited
for nearby PN (D ≤ 3.5 kpc), so the
surface fluxes less than other distance scales. With these criteria the results
showed that the proposed distance scale is more accurate than other scales
related to the observations for adopted sample of PN distances, also the limit
of ionized radius (Rio) for all both optically thick and optically thin in the rang of sizes (0.45
> Rio (pc) > 0.03).
Studying of operation balance in single-phase induction motors is an issue of interest due to the need for reducing the power consumption and increasing the motors’ life. The paper focuses on improving the motor performance by balancing the stator phase operation for the most common-used connection diagrams of single-phase capacitor-run induction motors (SPCRIMs) and three-phase induction motors (TPIMs) operating from single-phase supply (SPS). Therefore, a mathematical model is used to balance the motor operation by varying the frequency supply voltage. Characteristics of balancing parameters are investigated, various methods of motor balancing are presented and comparisons were done among these balancing methods.