SYS SIM Lec 1 - 3 Quiz 1 Flashcards
___ is the IMITATION of the operation of a
real-world process or system over time.
Simulation
Either done by hand or on a computer, simulation involves the generation of an ______ of a system, and the observation of that is to draw _____ concerning the operating characteristics of the real system
– artificial history
– inferences
___ Is the PROCESS of creating and analyzing a digital
prototype of a physical model to predict its performance in the real world
Simulation Modelling
____ is a MATHEMATICAL MODEL that calculates the
impact of (uncertain) inputs and the decisions we make on the outcomes that we care about (such as profit, loss, investment returns, etc.)
Once developed and validated, it can be used to
investigate a wide variety of “what-if” questions and the potential changes to the system that can predict their impact on system performance
Simulation Model
A Simulation model will include:
➢ ______ – these are the (uncertain) numbers/variables
➢ ______ (numerical parameters)
➢ ______ – these are the functions of interest
Model inputs
Intermediate calculations
Model outputs
simulation modeling can be used both as an _____ tool for predicting the effect of changes to existing systems, and as a _____ tool to predict the performance of new systems under varying sets of
circumstances.
– analysis
– design
When is Simulation the appropriate tool?
GIVE 7
(essay)
- It enables the STUDY of, and EXPERIMENTATION with, the INTERNAL INTERACTIONS of a complex system, or of a subsystem within a complex system.
(ex. System dynamics – growth & underinvestment) - The KNOWLEDGE gained in designing a simulation model may be of GREAT VALUE toward SUGGESTING IMPROVEMENT in the system under investigation
(ex. Public transport systems, automation initiatives – warehouse, floor shop, etc.) - By changing simulation inputs and observing the resulting outputs, VALUABLE INSIGHT may be obtained into WHICH variables are most IMPORTANT and HOW variables INTERACT.
(ex. Chemical reaction analyses) - It can be used to experiment with new designs or policies PRIOR to IMPLEMENTATION, so as TO PREPARE for what may happen. (ex. queueing model)
- By simulating different capabilities for a machine, REQUIREMENTS can be DETERMINED.
(ex. Production floor capacity adjustments, quality controls) - Its models designed FOR TRAINING allow learning without the cost and disruption of on-the-job learning.
(ex. Flight simulations, military strategy simulations, race car driving, etc.) - The MODERN SYSTEM (factory, wafer fabrication plant, service organization, etc.) is so COMPLEX that the interactions can be treated ONLY THROUGH SIMULATION
Essay: When is Simulation NOT the appropriate tool?
GIVE 6 RULES
First rule: when the problem can be solved using COMMON SENSE.
Second rule: if the problem can be SOLVED ANALYTICALLY.
Third rule: if it is EASIER to PERFORM direct
experiments.
Fourth rule: If the cost of the simulation study EXCEEDS the possible SAVINGS.
Fifth rule: if the resources (or time) is not available.
Sixth rule: If there is not enough time (or personnel) to verify and validate the model, then the simulation is not appropriate
ESsay: Give 6 Simulation usage Advantages
- REDUCED DISRUPTIONS of real-world operations.
- New hardware designs, physical layouts, transportation systems (etc.) can be tested WITHOUT committing RESOURCES for acquisition.
- Phenomenon/phenomena occurring can be tested FOR FEASIBILITY.
- TIME can be compressed (or expanded) to the phenomena under investigation.
- INSIGHTS can be obtained about the interaction of variables.
- Helps to understand how the system operates rather than how individual thinks the system operates.
- The “What-if” questions can be answered.
4 Simulation usage Disadvantages
- Model building requires special TRAINING.
- Simulation results may be DIFFICULT TO INTERPRET
– ex. an observation could either be a result of system interrelationships or randomness. - Simulation modelling and analysis can be TIME CONSUMING and EXPENSIVE.
- Some closed-form models are not able to analyze most of the complex systems that are encountered in practice.
3 Challenges and Limitations of Simulation
❑ Computational Complexity
o Large-scale simulations require high computing power.
❑ Data Accuracy & Assumptions
o Poor input data can lead to misleading results.
❑ Interpretation of Results
o Misinterpretation can lead to incorrect decisions
One of the Main Types of Systems Simulation
__________
- Models systems where events occur at specific points in time.
ex. Bank teller queue simulation, Traffic light control in urban planning.
Discrete-Event simulation
One of the Main Types of Systems Simulation
__________
- Models systems that change continuously over time rather than in discrete
steps.
ex. Climate modeling for weather predictions, Fluid dynamics simulations
- Continuous Simulation
One of the Main Types of Systems Simulation
_______
(combination of discrete and continuous – complex systems)
ex. discrete event for patient arrivals and continuous simul. for disease progression
Hybrid Simulation
read only
SImulation: AReas for application
✓ Healthcare
▪ Simulating patient flow in emergency rooms
▪ Drug testing simulations before clinical trials
✓ Manufacturing & Logistics
▪ Production line optimization
▪ Design of a toll plaza
▪ Choosing between rental-car locations
✓ Business Process Simulation
▪ Bank connection redesign on airport gate assignment
▪ Personnel forecasting and strategic workforce planning
✓ Safety and Construction Engineering
▪ Crash test (virtual car) for Designing safer cars
▪ Testing proposed bridge design
_____ are group of objects that are joined together in some regular
interaction or interdependence toward the accomplishment of some purpose
System
T or F
In modelling systems, it is necessary to decide on the boundary between the system and its environment.
T
5 components of a system
Entity
Attribute
Activity
State (Variables)
Events
One of the components of a system:
___ is an object of interest in the system
Entity
One of the components of a system:
___ is a property of an entity
Attribute
One of the components of a system:
___ is an activity with a time period of specified length
Activity
One of the components of a system:
___ that collection of variables necessary to describe the system at any time (relative to the objectives of the study)
State (variables)
_____ is the representation of the real-world system for the purpose of studying that system.
➢ For most studies, it is necessary to consider only those aspects of the system that affect the problem under investigation
Model
One of the components of a system:
_____ are instantaneous occurrences that may change the state of the system
Events
2 types of Events
a. _____ – activities/events occurring within the system
b. _____ – activities/events in the environment that affect the system
Endogenous
Exogenous
3 types of Models of a system
- Static/Dynamic models
- Deterministic/Stochastic models
- Discrete/Continuous models
2 of the types of models
_______ simulation – (Monte Carlo Simulation) represents a system at a particular POINT in time.
(ex. car failure probability based on component failure data)
*_______ simulation – represents the system as they CHANGE over time
(ex. bank simulation from 9:00AM to 4:00PM, traffic flow simulation from 6:00AM to 11:00AM)
- STATIC SIMULATION
- DYNAMIC SIMULATION
One of the types of models
____ have KNOWN set of inputs which will result on a unique set of output
Deterministic models
(ex. arrivals at a dentist’s office if all patients arrive at a scheduled appointed time)
One of the types of models
has one or more random variables as inputs (random
inputs lead to random output)
Stochastic model
Ex. Random inter-arrival times and random service times in a bank
(output) average no. of people waiting, average no. of waiting time
One of the types of models
the state variables change only at a discrete set of points in time.
Discrete model
One of the types of models
The state variables change continuously over time. (ex. Water level of a dam with a lake behind the dam affected by weather through rain storm and evaporation)
Continuous model
12 STEPS IN A SIMULATION STUDY (IN ORDER)
1 – Problem Formulation
2 – Setting Objective and OVerall Project Plan
3 – Model Conceptualization
4 – Data Collection
5 – Model Translation
6 – Model Verification
7 – Model Validation
8 – Experimental Design
9 – Production runs and Analysis
10 – More Runs?
11 – Documentation and Reporting
12 – Implementation
One of the steps in Simulation Study:
____ is the determination whether simulation is
the appropriate methodology for the problem as formulated in the objectives)
2 – Setting Objective and OVerall Project Plan
One of the steps in Simulation Study:
__ is the selection of the application on where the model will be simulated (Arena, AutoMod, ProModel, Taylor Enterprise Dynamics, etc)
Model Translation
One of the steps in Simulation Study:
Question to be answered: is the computer program
performing properly? (correct input parameters are checked with debugging
Model Verification
One of the steps in Simulation Study:
Questions: is the model an accurate representation of the real-system under study?
It is usually achieved through model calibration (iterative model comparison of digital system to actual system behavior)
Model Validation
One of the steps in Simulation Study:
____ are the alternatives that are to be simulated must be determined
Experimental Design
One of the steps in Simulation Study:
______ are used to estimate the
measures of performance for the system designs that are being simulated.
Production runs and analysis
Type of Documentation and reporting
a. ________ – necessary for understanding the program and possible future modifications. Parameter changes could analyze some output measure of performance.
b. ________ – written history of a simulation project.
Program documentation
Progress documentation
____ is a powerful modeling technique used to
represent and analyze complex systems where changes occur at discrete points in time
Discrete Event Simulation
Note: focuses on specific events that trigger state
changes in the system.
This approach is particularly useful for systems where the timing and sequence of events are critical, such as queueing systems, manufacturing
processes, and healthcare operations.
DES / Discrete Event Simulation
___ is described by its calling population, the nature of the arrivals, the service mechanism, the system capacity, and the queueing discipline
In the single-channel queue, the calling population is _____
– queueing system
– infinite
NOTE:
➢ In the single-channel queue, the calling population is infinite,
➢ Arrivals for service occur one at a time in a random fashion; once they join the
waiting line, they are eventually served,
➢ service times are of some random length according to a probability distribution
which does not change over time.
Simulations of queueing systems generally require the maintenance of an ____ for determining what happens next.
Simulation clock times for arrivals and departures are computed in a ____ customized for each problem
– Event list
– simulation table
Problem Solving
https://www.youtube.com/watch?v=0aucm40TZxY
