Publish in OALib Journal
APC: Only $99
The 27-level cascaded multilevel inverter (CMLI) is a popular CMLI, since it can produce an output voltage with nearly sinusoidal wave form and may be realized as a trinary asymmetric CMLI that consists of only three H-bridges. A new approach using a mixed integer linear programming (MILP) model is applied, that can determine the switching angles of this CMLI that minimize the values of any undesired harmonics. The model is applied first to determine the number of harmonics to be minimized to obtain least percentage total harmonic distortion (%THD) utilizing the 13 positive levels of the inverter. The obtained result is then included in the model and it is solved for different values of the output voltage. Single phase and three phase cases are investigated. The results show very low values of %THD and low order harmonics over wide voltage range till the 91st harmonic in both cases, which agree with the IEEE standards 519-1992 for voltage distortion limits till 161 kv.
Effects of tie beam length, width and overlap
stress on settlement of foundations have been investigated. In this
investigation square concrete footings have been used with dimensions (B × B × d) where (d) is footing depth and (B) is
footing width (1, 1.5,2 m).
Width of tie beam (b) has been taken equal to 0.25, 0.30, 0.40, 0.50 and 0.75
(m). Tie beam length (L) has been taken varying from B till 3B with same footing depth = 0.50
m. Effect of overlap stress on settlement as well as effect of tie beam width
and length on settlement has been determined. Also, the efficiency of tie beam
length and width has been obtained. An equation is presented to compute the
overlap stress zone in case of existing tie beam. It is found that the settlement increases with increasing the length of tie beam which
is clear after the effect of the overlap stresses zone. The width of overlap stress zone case of
existing tie beam has been found to be equal to (1.6 -1.75) B. The settlement of footings decreases with
increasing tie beam width. It is found that the settlement after the effect of
the overlap stress zone increases with increasing the length of tie beam.
Background: Cesarean delivery has become the most
common major surgical procedure in many parts of the world. Induction of labor
in women with prior cesarean delivery is an alternative to mitigate the rising
cesarean rates. Objectives: To compare the VBAC success rate between two
vaginal forms of dinoprostone for labor induction in women with prior cesarean
section. Material and Methods: A pilot study was
conducted at a large Governmental Hospital, Dhahran, Saudi Arabia,
including 200 women with prior cesarean
section and planned for labor induction. Participants were randomly
allocated into two groups. Group A (n = 100) received dinoprostone 1.5 mg vaginal
tablet. Group B (n = 100) received 10 mg dinoprostone sustained release vaginal
pessary. Primary outcome was vaginal delivery rate. Secondary outcomes included
maternal and neonatal outcomes. Results: The dinoprostone vaginal tablet and
dinoprostone vaginal pessary had a comparable vaginal delivery rate (67% and
64%, respectively; p = 0.78). The median patient satisfaction with the birth
process was superior in the dinoprostone vaginal pessary group (p = 0.04).
Maternal and neonatal outcomes were similar in both groups. Conclusion: Both
forms of dinoprostone were effective methods for labor induction in women with
prior cesarean section. However, the patient satisfaction with the birth
process was in favor of the dinoprostone sustained release vaginal pessary.