Analysis of MAP/PH/c Retrial Queue with Phase Type Retrials – Simulation Approach

Author(s):  
Srinivas R. Chakravarthy
2018 ◽  
Vol 7 (4.10) ◽  
pp. 758
Author(s):  
P. Rajadurai ◽  
R. Santhoshi ◽  
G. Pavithra ◽  
S. Usharani ◽  
S. B. Shylaja

A multi phase retrial queue with optional re-service and multiple working vacations is considered. The Probability Generating Function (PGF) of number of customers in the system is obtained by supplementary variable technique. Various system performance measures are discussed. 


2014 ◽  
Vol 31 (02) ◽  
pp. 1440010 ◽  
Author(s):  
YANG WOO SHIN ◽  
DUG HEE MOON

We consider the PH/PH/c retrial queues with PH-retrial time. Approximation formulae for the distribution of the number of customers in service facility, sojourn time distribution and the mean number of customers in orbit are presented. We provide an approximation for GI/G/c retrial queue with general retrial time by approximating the general distribution with phase type distribution. Some numerical results are presented.


1972 ◽  
Vol 69 (1) ◽  
pp. 67-76
Author(s):  
Rolf Plesner

ABSTRACT Twenty-two fertile women were treated cyclically in from 4–30 cycles (mean 15.5) with a total of 341 injections of Deladroxate®, an injectable, long-acting oestrogen-progestogen. The injections were administered on the 8th (7th–9th) day of each cycle. Before treatment, the last pre-treatment cycle was controlled by means of daily recordings of the basal body temperature (BBT), urinary excretion of pregnanediol and total pituitary gonadotrophins at certain intervals, and by endometrial biopsies obtained late in the cycle. The effects of Deladroxate® on ovulation, on pituitary gonadotrophic function, and on the endometrium were controlled by the above mentioned parameters during cycles 1, 3, and 6, and all assessments were repeated after discontinuation of treatment. During treatment, there was a statistically significant fall in gonadotrophin excretion values (as compared with the pre-treatment values), and the fall was found to be gradually progressive during treatment. After discontinuation of treatment, there seemed to be a tendency towards an increase in the excretion values. Suppression of ovulation as determined by means of the pregnanediol excretion during treatment, was effective in nearly all of the treatment cycles checked. The fall in pregnanediol excretion was also gradually progressive during treatment, while there was a slight increase in excretion values in the post-treatment period. During treatment, 79 BBT curves were recorded. Nearly 50 % were monophasic, indicating anovulatory cycles, 17 curves were biphasic, but with the rise in temperature occurring at non-characteristic times in the cycles, 18 curves were classified as thermogenic because of a rise in temperature occurring within 24 hours after the injection, and 5 curves were not assessable. During the first month after discontinuation of treatment, 8 out of 10 recorded curves were monophasic. Out of 53 endometrial biopsies obtained around the 23rd day of the cycle, 31 were of the mixed phase type, but showing a predominance of proliferative patterns, 15 were of the secretory type, and 7 were purely proliferative. Out of 15 biopsies obtained in the post-treatment period, only two were of the mixed phase type, 12 were proliferative and one was purely secretory.


2019 ◽  
Author(s):  
Samer Wakim ◽  
Maroun Nemer ◽  
B. Zeghondy ◽  
Boutros Ghannam ◽  
C. Bouallou

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