Quantitative Methods with Modeling and Simulation - Simulation and Modelling

Summary

This video introduces modeling and simulation, explaining how simulations are used to imitate real-world systems through computer models. It covers the benefits of simulation, such as optimizing performance and preventing issues, and details the process of developing a simulation model, from problem identification to model validation. The video also discusses different types of simulations, including live, virtual, and constructive, and highlights common pitfalls to avoid in simulation studies. Overall, the video emphasizes the value of simulation in analyzing and improving complex systems safely and efficiently.

Takeaways

• 🛠️ Simulation is the process of creating an imitation of a real-world system using a computer model.
• ✈️ A flight simulator on a PC is an example of a simulation, showing how controls and views from a cockpit can be mimicked.
• 📉 Simulation is used to reduce failure risks, predict bottlenecks, optimize resources, and enhance system performance before altering or building new systems.
• 📡 Simulation can answer complex questions about the best design, resource requirements, and performance impacts in telecommunications networks.
• 📝 Modeling involves creating a representation of a system to predict outcomes based on different actions, and is simpler than the real system it represents.
• 💡 Models, like flight simulators, are used because experimenting with real systems can be costly, dangerous, or impossible.
• 🔍 Simulation is beneficial when multiple factors influence system behavior and allows for simultaneous handling and analysis of these factors.
• 💻 Simulations can be manual or, more commonly, computer-based, involving software to implement the model over time.
• 🧩 There are three types of simulations: live (real people and systems), virtual (real people, simulated systems), and constructive (simulated people and systems).
• 🔧 Developing a simulation model involves identifying the problem, formulating it, collecting data, creating the model, validating it, and documenting for future use.
• 📊 Benefits of simulation modeling include better system understanding, hypothesis testing, time compression or expansion for observation, and safe experimentation with system models.
• 🚧 Simulation modeling helps identify driving variables, bottlenecks, and allows for the use of multiple performance metrics and a system approach to problem-solving.
• ⚠️ Common pitfalls in simulation include unclear objectives, invalid or overly complex models, undocumented assumptions, wrong input distributions, bugs, and poor communication.

Q & A

What is simulation in the context of operations research?

Simulation in operations research is the process of pretending to deal with a real system by working with an imitation, typically a computer model, of the simulated reality.

How does a flight simulator serve as an example of simulation?

A flight simulator on a PC models some aspects of a flight, showing the controls and the pilot's view from the cockpit. It allows training and experimentation without the risks and costs associated with real flights.

What are the key purposes of using simulation before altering or building a system?

Simulation is used to reduce the chances of failure to meet specifications, identify unforeseen bottlenecks, prevent under or over-utilization of resources, and optimize system performance.

What types of questions can simulation help answer regarding telecommunications networks?

Simulation can help determine the best design for a new network, resource requirements, performance under increased traffic load, the impact of new routing algorithms, and the effects of link failures.

What is a model in the context of modeling and simulation?

A model is a representation of the construction and working of a system, intended to predict what happens if certain actions are taken. It is simpler than the actual system but serves to forecast the effects of changes.

Why are models used instead of real systems for experiments?

Models are used because experimenting with real systems can be costly, dangerous, and sometimes impossible. Adequate models can save money, reduce risk, and provide valuable insights without disrupting the real system.

What are the three types of commonly used simulations?

The three types are live simulations (involving real people operating real systems), virtual simulations (involving real people operating simulated systems), and constructive simulations (involving simulated people operating simulated systems).

What are the main steps involved in developing a simulation model?

The steps include identifying the problem, formulating the problem, collecting real system data, formulating and developing the model, validating the model, and documenting the model for future use.

What are some benefits of simulation modeling and analysis?

Benefits include better understanding of the system, hypothesis testing, time compression or expansion to observe phenomena, studying the effects of changes without disrupting the real system, and identifying driving variables and interrelationships.

What are some common pitfalls to guard against in simulation modeling?

Pitfalls include unclear objectives, using simulation when an analytic solution is appropriate, invalid or overly complex models, undocumented assumptions, incorrect input probability distributions, wrong performance measures, and poor communication among personnel.

Outlines

00:00

📚 Introduction to Modeling and Simulation

This video provides an introduction to modeling and simulation. Simulation involves creating a computer model to imitate reality, such as a flight simulator. It is used to reduce failure risks, identify bottlenecks, optimize resources, and enhance system performance. Modeling creates a representation of a system to predict outcomes. Examples include using flight simulators for safe and cost-effective training. Simulations help analyze system interactions and improve performance by addressing factors influencing system behavior.

05:04

🔍 Types of Simulations

There are three main types of simulations: live, virtual, and constructive. Live simulations involve real people operating real systems. Virtual simulations have real people interacting with simulated systems, focusing on skills like motor control and decision-making. Constructive simulations involve simulated people operating simulated systems, allowing for analysis and prediction of outcomes without real people determining the results. Each type has distinct applications and benefits in analyzing and improving system performance.

10:06

🛠 Developing a Simulation Model

Developing a simulation model involves several steps. First, identify the problem by outlining issues with the existing system or requirements for a new system. Next, formulate the problem by setting system boundaries, objectives, and performance measures. Collect real system data and develop the model using simulation software. Validate the model by comparing its performance with real system data and ensuring accuracy through expert review. Document the model thoroughly for future use and reference.

15:11

💡 Benefits of Simulation Modeling and Analysis

Simulation modeling and analysis offer numerous benefits. They provide a better understanding of systems by allowing detailed observation over time. Hypotheses about system feasibility can be tested without disrupting the real system. Simulation allows for the study of long-term and complex phenomena and the effects of various changes on system operations. It helps identify critical variables, analyze system configurations using multiple performance metrics, and develop robust systems, ultimately reducing development time and risks.

⚠️ Pitfalls to Avoid in Simulation

Several pitfalls must be avoided in simulation modeling. Objectives must be clear, and simulation should not be used when an analytic solution is possible. The model should be appropriately complex and assumptions documented. Using incorrect input distributions or performance measures can lead to inaccurate results. Ensuring independence in simulation output data and avoiding biases are crucial. Multiple simulation runs are necessary for reliable results. Effective communication among team members is vital for a successful simulation study.

Keywords

💡Simulation

Simulation refers to the imitation of a real-world process or system. In the context of the video, it is used to explore and analyze a system's behavior under various conditions without the risks and costs associated with real-world experiments. For example, a flight simulator is a computer model that mimics the experience of flying, allowing pilots to train without the dangers of actual flight.

💡Modeling

Modeling is the process of creating a simplified representation of a system to study its behavior under certain conditions. It is crucial for predicting outcomes of changes within the system. The video emphasizes the importance of modeling in operations research, where it helps in understanding complex systems and making informed decisions, such as in the design of a new telecommunications network.

💡Operational Research

Operational Research is an interdisciplinary approach that uses advanced analytical methods to help make better decisions. In the video, it is mentioned in the context of using simulation and modeling to analyze and optimize systems, such as in the case of improving telecommunication networks or developing new routing algorithms.

💡Computer Model

A computer model is a type of mathematical representation used to simulate the behavior of a system. The video script mentions flight simulators on PCs as examples of computer models that display controls and visual representations to mimic the experience of flying, highlighting the use of technology in simulation.

💡Performance Measures

Performance measures are quantitative criteria used to evaluate the effectiveness of a system or model. The video discusses how these measures are essential for comparing different system configurations and assessing their performance under various conditions, such as the impact of increased traffic load on a telecommunication network.

💡System Entities

System entities are the components or elements within a system that interact with each other. In the video, they are part of the simulation model and are crucial for understanding the dynamics of the system being studied, such as the various components of a telecommunication network.

💡Input Variables

Input variables are the factors that can be manipulated in a simulation to observe their effects on the system's behavior. The video script uses the example of altering traffic load to demonstrate how input variables can be used to test different scenarios in a simulated environment.

💡Functional Relationships

Functional relationships describe how different components of a system interact and influence each other. The video emphasizes the importance of understanding these relationships in the development of a simulation model to accurately represent the real-world dynamics of the system.

💡Live Simulation

Live simulation is a type of simulation that involves real people operating real systems. The video script explains that live simulations provide a realistic environment for training or testing, as they closely replicate actual activities, such as using actual equipment in a controlled setting.

💡Virtual Simulation

Virtual simulation involves real people interacting with simulated systems. The video describes how virtual simulations place humans in a central role, allowing them to exercise motor control, decision-making, and communication skills within a simulated environment, such as a flight simulator.

💡Constructive Simulation

Constructive simulation is a type of simulation where simulated entities operate within simulated systems. The video script highlights that constructive simulations enable the analysis of concepts, prediction of outcomes, and stress testing of large organizations, making them a powerful tool for planning and analysis.

Highlights

Introduction to modeling and simulation.

Definition of simulation: pretending to deal with a real thing while working with an imitation.

Simulation is used to reduce the chances of failure and optimize system performance.

Examples of simulation questions: best design for a new network, resource requirements, impact of traffic load increase.

Definition of modeling: producing a representation of a system to predict outcomes of certain actions.

Purpose of models: safer and cheaper experimentation compared to real systems.

Simulation is useful when many factors influence system behavior.

Simulations can be performed manually or using computer programs and software.

Types of simulations: live, virtual, and constructive.

Live simulation: real people operating real systems.

Virtual simulation: real people operating simulated systems, involving motor control, decision, and communication skills.

Constructive simulation: simulated people operating simulated systems, with real people providing inputs but not determining outcomes.

Steps in developing a simulation model: identifying the problem, formulating the problem, collecting real system data, developing the model, validating the model, and documenting the model.

Benefits of simulation modeling: better understanding of systems, testing hypotheses, observing long-term phenomena, studying system changes without real-world disruption.

Pitfalls to guard against in simulation: unclear objectives, invalid models, wrong input distributions, and poor communication.

Transcripts

good day everyone

this video will give you an introduction

on modeling and simulation

so let's start

what is simulation simulation

in general is to pretend that

one deals with a real thing while really

working with an

imitation in

operations research the imitation

is a computer model of the simulated

reality

for example a flight simulator on a pc

is also a computer model of some aspects

of the flight

it shows on the screen the controls and

what the pilot is supposed to see

from the cockpit now based on this

example

we can say that simulation is used

before

an existing system is altered or a new

system

is built to reduce the chances of

failure to meet specifications

to imitate unforeseen bottlenecks

to prevent under or over utilization of

resources

and to optimize system performance

simulation can be used to answer

questions like what is the best design

for a new telecommunications network

what are the associated resources

requirements

how will a telecommunication networks

perform

when the traffic load increases by 50

how will a new routing algorithm affects

its performance

which network protocol optimizes network

performance and what will the

uh what will be the impact of a link

failure

next is modeling modeling is the process

of producing a model a model

is a representation of the construction

and working of

some system of interest a model

is descript is a description of some

system

intended to predict what happens if a

certain action

are taken a model is similar

to but simpler than the systems

or system it represents one purpose of a

model is to enable the analyst

to predict the effects of changes

to the system

now why do we use models

let us take again the flight simulator

on the pc as an example

flying in a simulator is safer and

cheaper than the real airplane

for precisely this reason models are

used it is very costly

dangerous and often impossible to make

experiments

with real systems provided that the

model

are adequate descriptions of reality

experimenting with them can save money

suffering

and even time

so when do we use a simulation or

simulation

the use of simulation becomes apparent

as soon as a number of factors

are considered to influence the behavior

of

a system many approaches especially

statistical ones are available

to analyze interactions in systems

simulation modeling constitutes a unique

approach

that it enables the simply the

simultaneous handling

end range of such factors and see

their influence on the behavior of a

system

the next is how is simulation

performed

simulations may be performed manually

most often however the system model

is written either as a computer program

or as some kind of input

into sim simulator software

as you can see on the example

illustration

so what are the different types of

simulator

a simulator is a device or a computer

program

or a system that performs

simulation a simulation

is a method for implementing a model

over time there are three

types of commonly used

simulations the live

virtual and constructive

now live is a simulation involving real

people

operating real system

so uh in the live

simulations it involves individual or

groups

may use actual equipment should provide

a similar area of operations

should be close to replicating the

actual activity

the second type is the virtual

simulation involving real people

operating

same simulated system virtual

simulations inject human

in the loop in a central role

by exercising it involves

motor control skills decision skills and

communication skills

the third is the constructive simulation

now constructive simulation involves

simulated people operating simulated

systems

real people can stimulate

or make inputs but are not involved in

determining the outcomes

constructive simulation offered the

ability to

analyze concepts predict possible

outcomes

stress large organizations

make measurements generate statistics

and perform analysis

we now go to developing a simulation

model

simulation model consists of the

following components

system entities input variables

performance measures and

functional relationships

simulation modeling comprises of the

following steps

the first step is identifying the

problem

when uh in step one

uh enumerate problems with an existing

system

produce requirements for a proposed

system step 2

[Music]

formulate the problem

this means that select the bounds of the

system

the problem or a partner of

to be studied define overall

objective of the study in a few specific

issues

to be addressed we also need to define

performance measures quantitative

criteria

on the basis of which different system

configurations will be compared

and rank we have to identify also

briefly at this stage the

configurations of interest and formulate

hypotheses

about system performance

we also need to decide the time frame of

the study

example will be the model used

for one time decision

or over a period of time on a regular

basis

and lastly identify the end user of the

simulation model

the third step is collect the process

real system data this means that

collect data on system specifications

input variables as well as performance

of

the existing system

step four formulate and develop a model

in step four developing semantics and

network diagrams of the system

translate these conceptual models to

simulation software acceptable form

verify that the simulation model

executes

as intended step 5

validate the model this means that we

need to

compare the model's performance under

known conditions

with the performance of the real system

perform statistical interference test

and get the model examined

by system experts assess the confidence

that the end user places on the model

and address problems if there are any

lastly document model

for future use document objectives

assumptions and input variables

in detail

the next topic is what are the benefits

of simulation modeling and analysis

according to practitioners

simulation modeling and analysis is one

of the most

frequently used operations research

techniques when used judiciously

simulation modeling and analysis makes

it possible

to

first obtain a better understanding of

the system

by developing a mathematical model of a

system

of interest and observing the system's

operation

in detail over long periods

of time next test hypothesis

about the simula about the system

for visibility

next we have compressed time to observe

certain phenomena

over long periods or expand time to

observe

a complex phenomenon in detail

study the effects of certain information

organizational environmental and policy

changes

on the operation of a system by altering

the system's model

this can be done without disrupting the

real system

and significantly reduces the risk of

experimenting with the real system

lastly

experiment with you or unknown

situations

about which only weak information is

available

another benefits of simulation modeling

analysis

is

identify the driving variables

ones that performance measures are most

sensitive

to and the interrelationships

among them next

another bottlenecks in the flow

of entities or information

next is use multiple performance metrics

for analyzing system configuration

another is employ a system approach to

problem solving

and lastly develop well-designed

and robust systems and reduce system

development time

we now go to our last topic which is the

pitfalls of guard

against pitfalls to guard against

in simulation

can be a time consuming and complex

exercise

for modeling through output analysis

that necessitates the involvement of

residents

experts and decision makers in the

entire process

following is a checklist of pitfalls to

guard

against

first and clear

objective second

using simulation when analytic solution

is appropriate

next is invalid model

another is simulation model is too

complex or too simple

next is a red news assumptions

another is undocumented assumptions

this is extremely important and it is

strongly suggested

that assumptions made at each stage of

dissemination modeling and analysis

exercise

by documented thoroughly

another is using the wrong input

probability distribution

next is replacing a distribution by its

means

next is using the wrong performance

measure

next is bugs in the simulation program

another is using standard statistical

formulas that assume

independence in simulation output

analysis

next is initial bias in output data

another is making one simulation run for

a configuration

next is sports schedule and budget

planning

and the last poor communication among

the personnel involved

in the simulation study

and that concludes this lesson thanks

for listening