NONSTATIONARY LOSS QUEUES VIA CUMULANT MOMENT APPROXIMATIONS

2014 ◽  
Vol 29 (1) ◽  
pp. 27-49 ◽  
Author(s):  
Jamol Pender
Keyword(s):  
Series Expansion ◽  
Performance Measures ◽  
Blocking Probability ◽  
Numerical Examples ◽  
The Mean ◽  
A New Technique ◽  
Erlang Loss ◽  
Forward Equations ◽  
Kolmogorov Forward Equations ◽  
Mean Variance

In this paper, we provide a new technique for analyzing the nonstationary Erlang loss queueing model with abandonment. Our method uniquely combines the use of the functional Kolmogorov forward equations with the well-known Gram-Charlier series expansion from the statistics literature. Using the Gram-Charlier series expansion, we show that we can estimate salient performance measures of the loss queue such as the mean, variance, skewness, kurtosis, and blocking probability. Lastly, we provide numerical examples to illustrate the effectiveness of our approximations.

The disasters queue with working breakdowns and impatient customers

2020 ◽  
Vol 54 (3) ◽  
pp. 815-825
Author(s):  
Mian Zhang ◽  
Shan Gao
Keyword(s):  
Size Distribution ◽  
Performance Measures ◽  
Sojourn Time ◽  
Queue Length ◽  
Slow Rate ◽  
System Size ◽  
Impatient Customers ◽  
Numerical Examples ◽  
The Mean ◽  
Mean Queue Length

We consider the M/M/1 queue with disasters and impatient customers. Disasters only occur when the main server being busy, it not only removes out all present customers from the system, but also breaks the main server down. When the main server is down, it is sent for repair. The substitute server serves the customers at a slow rate(working breakdown service) until the main server is repaired. The customers become impatient due to the working breakdown. The system size distribution is derived. We also obtain the mean queue length of the model and mean sojourn time of a tagged customer. Finally, some performance measures and numerical examples are presented.

EARLY RESULTS OF SINGLE-PORT LAPAROSCOPIC APPENDECTOMY

2017 ◽  
pp. 103-106
Author(s):  
Minh Duc Pham
Keyword(s):  
Laparoscopic Appendectomy ◽  
Single Port ◽  
Operation Time ◽  
Invasive Procedure ◽  
Minimal Invasive ◽  
University Hospital ◽  
Early Results ◽  
Sils Port ◽  
The Mean ◽  
A New Technique

Background: Conventional three–port laparoscopic appendectomy is becoming popular for the treatment of acute appendicitis. In this report, we present the early results of a new technique of laparoscopic appendectomy conducted through a single-port. Patients and Methods: From March 2011 to October 2013, we have performed 86 operations Single Port Laparoscopic Appendectomy at Hue University Hospital and Hue Central Hospital. SILS Port (Covidien) is used, it can be performed with basic laparoscopic instruments. Results: In this study, 86 patients underwent Single-Port laparoscopic appendectomy, among them 52.33% were femele, 47.67% were male, female/male ratio was 1.09. The mean age was 33.09. An orther trocar insertion was required in 2 patients (2.33%). The mean operation time was 42.03 minutes and mean postoperative hospital stay 3.37 days. Postoperative complication occurred in 2 case (2.33%) was of omphalitis. During 2 weeks follow up, 2 case (2.33%) was of omphalitis. Conclusions: Single - port intracorporeal appendectomy is a safe, minimal invasive procedure with excellent cosmetic results. Key words: Single Port Laparoscopic Appendectomy, appendectomy

scholarly journals Sea Topography of the Ionian and Adriatic Seas Using Repeated GNSS Measurements

Water ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 812
Author(s):  
Sotiris Lycourghiotis
Keyword(s):  
Satellite System ◽  
Geoid Model ◽  
Sea Surface Topography ◽  
Mean Sea Surface ◽  
The Mean ◽  
A New Technique ◽  
Gnss Measurements ◽  
Global Navigation Satellite ◽  
Constant Slope ◽  
Ionian And Adriatic Seas

The mean sea surface topography of the Ionian and Adriatic Seas has been determined. This was based on six-months of Global Navigation Satellite System (GNSS) measurements which were performed on the Ionian Queen (a ship). The measurements were analyzed following a double-path methodology based on differential GNSS (D-GNSS) and precise point positioning (PPP) analysis. Numerical filtering techniques, multi-parametric accuracy analysis and a new technique for removing the meteorological tide factors were also used. Results were compared with the EGM96 geoid model. The calculated differences ranged between 0 and 48 cm. The error of the results was estimated to fall within 3.31 cm. The 3D image of the marine topography in the region shows a nearly constant slope of 4 cm/km in the N–S direction. Thus, the effectiveness of the approach “repeated GNSS measurements on the same route of a ship” developed in the context of “GNSS methods on floating means” has been demonstrated. The application of this approach using systematic multi-track recordings on conventional liner ships is very promising, as it may open possibilities for widespread use of the methodology across the world.

scholarly journals Functional and aesthetic outcomes of spreader graft and auto-spreader flap after nasal hump removal

2020 ◽  
Vol 36 (1) ◽  
Author(s):  
Maged Baher Naguib ◽  
Mohamed Rifaat Ahmed ◽  
Yasser Taha Madian ◽  
Tarek Mohamady Elnahriry ◽  
Wael Elshahat Eldeeb
Keyword(s):  
Nasal Obstruction ◽  
Operative Time ◽  
Nasal Valve ◽  
Spreader Graft ◽  
Spreader Flap ◽  
The Mean ◽  
The Difference ◽  
A New Technique ◽  
Nasal Valve Collapse ◽  
Duration Of Operation

Abstract Background Following the reduction of the nasal hump to a desired level, spreader grafts are usually positioned to prevent the complication of nasal valve collapse. Auto-spreader flap is a new technique that gained more popularity recently and can be used as an alternative to spreader graft. This RCCT compared between both techniques aesthetically and functionally as well as the operative time. Results Forty patients, 17 males (42.5%) and 23 females (57.5%), were included. The mean duration of operation in auto-spreader flap was 11.8 ± 3.4 min, while it was 19.2 ± 3.2 min in spreader graft. The difference between the two procedures was statistically significant (P < 0.05). Functional assessment of nasal obstruction was done for all patients in both groups preoperative that was (75.6 ± 19.9) which showed marked improvement when re-evaluated 3 moths postoperatively (18.9 ± 14.7), and after 6 months NOSE scale was (29.1 ± 20.2). The overall aesthetic satisfaction was 62.5% (25 of 40) irrespective of the surgery done. Sixteen out of 20 patients in spreader group and 9 out of 20 in auto-spreader flap group. Conclusion Auto-spreader flap and spreader graft are very effective surgical procedure for treatment of nasal obstruction due to internal nasal valve dysfunction, but the auto-spreader flap had shorter operative time. However, spreader graft has a superior aesthetic outcome.

Comparison Between the Mean-Variance Optimal and the Mean-Quadratic-Variation Optimal Trading Strategies

2013 ◽  
Vol 20 (5) ◽  
pp. 415-449 ◽  
Author(s):  
S. T. Tse ◽  
P. A. Forsyth ◽  
J. S. Kennedy ◽  
H. Windcliff
Keyword(s):  
Quadratic Variation ◽  
Trading Strategies ◽  
Optimal Trading ◽  
The Mean ◽  
Mean Variance

Stochastic Analysis of Temperature Distribution in a Solid With Random Heat Conductivity

1988 ◽  
Vol 110 (1) ◽  
pp. 23-29 ◽  
Author(s):  
Da Yu Tzou
Keyword(s):  
Thermal Conductivity ◽  
Temperature Distribution ◽  
Heat Conductivity ◽  
Stochastic Analysis ◽  
Solid Medium ◽  
Mean Value ◽  
Random Response ◽  
Thermal Failure ◽  
Numerical Examples ◽  
The Mean

Stochastic temperature distribution in a solid medium with random heat conductivity is investigated by the method of perturbation. The intrinsic randomness of the thermal conductivity k(x) is considered to be a distribution function with random amplitude in the solid, and several typical stochastic processes are considered in the numerical examples. The formulation used in the present analysis describes a situation that the statistical orders of the random response of the system are the same as those of the intrinsic random excitations, which is characteristic for the problem with extrinsic randomness. The maximum standard deviation of the temperature distribution from the mean value in the solid medium reveals the amount of unexpected energy experienced by the solid continuum, which should be carefully inspected in the thermal-failure design of structures with intrinsic randomness.

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