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Module: bcc .\simpy1_5\SimPyModels\bcc.py

Jobs (e.g messages) arrive randomly at rate $1.0$ per minute at a 2-server system. Mean service time is $0.75$ minutes and the service-time distribution is (1) exponential, (2) Erlang-5, or (3) hyperexponential with $p=1/8$,$m1=2.0$, and $m2=4/7$. However no queue is allowed; a job arriving when all the servers are busy is rejected.

Develop and run a simulation program to estimate the probability of rejection (which, in steady-state, is the same as $p(c)$) Measure and compare the probability for each service time distribution. Though you should test the program with a trace, running just a few jobs, the final runs should be of 10000 jobs without a trace. Stop the simulation when 10000 jobs have been generated. Use the random number stream 1 for all runs.

Imported modules   
from SimPy.Simulation import *
from __future__ import generators
from random import Random, expovariate, uniform
Functions   
ErlangVariate
HyperVariate
bcc
erlangB
main
testHyperVariate
  ErlangVariate 
ErlangVariate (
        mean,
        K,
        g,
        )

Erlang random variate

mean = mean K = shape parameter g = rv to be used

  HyperVariate 
HyperVariate (
        p,
        m1,
        m2,
        g,
        )

Hyperexponential random variate

p = prob of branch 1 m1 = mean of exponential, branch 1 m2 = mean of exponential, branch 2 g = rv to be used

  bcc 
bcc (
        lam,
        mu,
        s,
        )

bcc - blocked customers cleared model

  • returns p[i], i = 0,1,..s. - ps = p[s] = prob of blocking - lameff = effective arrival rate = lam*(1-ps)

See Winston 22.11 for Blocked Customers Cleared Model (Erlang B formula)

  erlangB 
erlangB ( rho,  c )

Erlang's B formula for probabilities in no-queue

Returns p[n] list see also SPlus and R version in que.q mmcK que.py has bcc.

use bcc instead!!

  main 
main ()

  testHyperVariate 
testHyperVariate ()

tests the HyerVariate rv generator

Classes   

Job

Jobs that are either accepted or rejected

JobGen

generates a sequence of Jobs


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This document was automatically generated on Tue Dec 07 19:52:27 2004 by HappyDoc version 2.1