Introduction to simulation and modeling will describe what is simulation, what is system and what is model. It will give a brief overview of simulation and modeling in computer science.
Simulation ---?
Simulation modeling is the process of
creating and analyzing a digital prototype
of a physical model to predict its
performance in the real world.
Simulation modeling is used to help
designers and engineers understand
whether, under what conditions, and in
which ways a part could fail and what
loads it can withstand.
Simulation in Computer science---
simulation has some specialized
meanings –
Alan Turing used the term
"simulation" to refer to what happens
when a universal machine executes a
state transition table that describes the
state transitions, inputs and outputs of
a subject discrete-state machine.
SimulationModeling Workflow---
Use a 2D or 3D CAD tool to develop a virtual
model, also known as a digital prototype
Generate a 2D or 3D mesh for analysis
calculations.
Define finite element analysis data based on
analysis type.
Perform finite element analysis, review
results, and make engineering judgments based
on results.
Simulationis Needed
experiment with new designs
or policies prior to
implementation
can be used to verify analytic
solutions
different capabilities for a
machine, requirements can be
determined.
designed for training allow
learning without the cost and
disruption of on-the-job
learning.
Simulation is not Needed
problem can be solved using
common sense
simulation costs exceed the
savings
Resources or time are not
available
system behavior is too complex
or can’t be defined.
isn’t the ability to verify and
validate the model.
Why is Modeling and Simulation Important in Engineering?
Unavailable input and output.
Experiment may be too dangerous.
Cost of experimentation might be too high.
Time constants of the system may not be compatible with human
dimensions.
Experimental behavior might be obscured by disturbances.
Advantage:
New polices, operating procedures, decision rules,
information flows, organizational procedures.
New hardware designs, physical layouts, transportation
systems.
Hypotheses about how or why certain phenomena occur can
be tested for feasibility.
Insight can be obtained about the interaction of variables.
Insight can be obtained about the importance of variables to
the performance of the system.
Disadvantages:
There are disadvantages in using a simulation model:-
We have a poor understanding of how some physical systems work so that we do
not have sufficient data to produce a mathematical model. For this reason it has not
been possible to create simulations that can accurately predict the occurrence and
effects of earthquakes and tsunami.
The formula and functions that are used may not provide an accurate description of
the system resulting in inaccurate output from the simulation.
Complex simulations can require the use of a computer system with a fast processor
and large amounts of memory.
Simulation results may be difficult to interpret.
Simulation modeling and analysis can be time consuming and expensive.
What is Model?
•Representation of a real or theoretical System.
•Simplification of the System.
•Understanding of the System.
Why we need modeling ?
Cost effective way to represent a real-world system.
Key aspects of the system, components.
And how those components communicate with one
another.
To test designs before implementation.
Model Types
• Visual Models : Graphical sketches, Computer solid
models
Physical Models: Prototypes, mock-ups, structural
models.
• Logical Models : Algebraic and different equation
used for computer simulation.
Empirical Models: Relationship between variables.
Deterministic Simulation Models
• A model that does not contain probability.
• Every run will result the same.
• Single run is enough to evaluate the result.
Stochastic Simulation Models
• A model that contains probability.
using random numbers.
Every run will result differently.
• Multiple runs are required to evaluate the
results.
Define An Achievable Goal
To model the…” is NOT a goal!
“To model the…in order to select/determine feasibility/…is a
goal.
Goal selection is not cast in concrete
Goals change with increasing insight
Modeling ---
Disadvantages:
Higher software cost .
Additional training required.
Limited portability.
Advantages:
Standard features often needed .
Shorter development cycle .
Very readable code.
What is a System:
A set of principles or procedures according to which
something is done; an organized scheme or method.
Primary objective is complete a task
Object are connected together
Follow set of defined rules
System Environment ---
where all the system objects are grouped together to accomplish
the task.
System Boundary:
System boundary are something to detect
whether the changes occurs inside the system
or outside the system
Endogenous:
Endogenous describe activities and events occurring within a system.
Exogenous
Exogenous describe activities and events in
an environment that affect the system