EVOLUTION OF INDUSTRIAL ENGINEERING Prof. Dr. Orhan TORKUL Res. Asst. M. Raşit CESUR Res. Asst. Furkan YENER

Simulation Computer simulation is the discipline of designing a model of an actual or theoretical physical system, executing the model on a digital computer, and analyzing the execution output. The motivation for the evelopment of simulation is the desire to be able to examine the details of the dynamics of a complex operating system. In particular, we can often gain valuable insight into system behavior by the detailed tracing of entities moving through the system. Simulation answers “what if” question.

Time – Flow Mechanism Initial Conditions Generate Next Customer Arrival time and enter on event list Queue + 1 = Queue Indicate server busy Generate Sevice End Time and Enter on Event List Select Next Event on List Indicate Server Free Is Server Busy? Is Queue =0? Queue - 1 = Queue No Yes No Yes Variable increment simulation flowchart

Time – Flow Mechanism According to variable increment simulation flowchart, an example of event- step incrementation is the flow chart of a queueing system having one service facility and infinite queue capacity. When a customer arrives for services, before being assigned to a server, we first generate the time of our next arrival and enter that arrival chronologically in the event list.

Example Below given operation process diagrams A and B, a company that produces products, to choose office layouts is considering making a simulation study. Simulation period within 4 hours of production values ​​for A and B are multiplied by 80, will be calculated monthly production quantities. According to the process flow lines, one from each type of machines are assumed to be used. Transport time between the machinery was ignored. Unit sales prices of products A and B, respectively, $100 and $120. This product of the unit cost of production is $ 55 and $ 50, respectively, again. The cost of each bench is $ 5000.

Example The time between the arrival times of the raw materials in the system, which average 40 minutes is an exponential distribution. The possibility of Product A and B, which are joined to the system, are 0,4 and 0,6. The processing time is the same for each bench 30 min - 40 min is distributed uniformly in the range. In the light of this information, the company, which is elective workplace layout ? A Lathe Milling Lathe B Milling Lathe Milling

Solution Solution : For each bench, processing times are the same and uniformly distributed; X = a + (b - a) * RN = 30+ ( ) * RN = * RN The time between the arrival times of the products in the system, which average 40 minutes is an exponential distribution. r = 1/40, X = -1/r * ln(RN) = -1/(1/40) * ln(RN) = - 40 * ln(RN) Bench costs are the same for Lathe and Milling, it is $5000 for unit.

Solution ProbabilityRandom Number Range A0,40,0 – 0,3 B0,60,4 – 0,9 Lathe Milling Lathe Milling Lathe Milling 0,40,6 AB Product B Product A Product Flow line Layout

Solution RN for TBA Moment of Arrival RN for processin g time and processin g time The RN for A and B and product type AB LatheMillingLatheMillingLatheMilling StartFinishStartFinishStartFinishStartFinishStartFinishStartFinish 0,620,4 0,3-330,6-B ,453,4 86,4 119,4 0,527,748,10,9-390,3-A48,187,1 126,3126,1165, ,436,784,80,2-320,9-B ,8116,8 148,8 180,8 0,88,993,70,7-370,8-B ,8153,8 190,8 227,8 0,192,1185,80,4-340,2-A185,8219,8 253,8 287,

Solution Finish time for this product, 287.8> 240 so this product is being currently considered yet. TBA : the Time Between Arrivals RN : Random Number Production period at the end of 4 hours, 3 unit B, and 1 unit of product A is produced. Total Profit = (100-50) * 80 – 3 * (120 – 55) * 240 – 3 * 5000 = - $10400

Solution According to Process Flow Lines, there are 1 unit lathe and 1 unit milling. LatheMilling 0,40,6 AB Product B Product A

Solution RN for TBA Moment of Arrival RN for processing time and processing time The RN for A and B and product type LatheMillingLatheMilling StartFinish.StartFinish. 0,192,1 0,4-340,6-B1-- 0,527,7119,80,2-320,9-B2 0,348,21680,1-31 0,2-A3 don’t finish

Solution

Simulation Software Although we now have a feel for simulation, we must realize that simulation is not merely an exercise in operating the model of a system. Instead, we try to collect important system performance measures as the simulation proceeds. For example, in the queueing system we may want to know the maximum length of the queue, the utilization of the server, or the average waiting time in the systemfor given arrival and service distributions

Simulation Software These things can be determined by building into the computer program approriate counters or registers to gather these statistical data. Better yet, we can make use of available simulation languages to do this work for us.

Simio SIMULATION

SIMIO - OBJECTS

SIMIO - FLOW

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