Simulation
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Wooden mechanical horse simulator during WWI.
A simulation is an imitation of some real thing, state of affairs, or process. The
act of simulating something generally entails representing certain key
characteristics or behaviours of a selected physical or abstract system.
Historically, the word had negative connotations:
…for Distinction Sake, a Deceiving by Words, is commonly called a Lye, and a
Deceiving by Actions, Gestures, or Behavior, is called Simulation… Robert
South (1643–1716)[1]
However, the connection between simulation and dissembling later faded out
and is now only of linguistic interest.
Simulation is used in many contexts, including the modeling of natural systems
or human systems in order to gain insight into their functioning. Other contexts
include simulation of technology for performance optimization, safety
engineering, testing, training and education. Simulation can be used to show the
eventual real effects of alternative conditions and courses of action.
Key issues in simulation include acquisition of valid source information about the
referent, selection of key characteristics and behaviours, the use of simplifying
approximations and assumptions within the simulation, and fidelity and validity of
the simulation outcomes.
Contents
[hide]
1 Classification and terminology
1.1 Physical and interactive simulation
1.2 Computer simulation
1.3 Simulation in computer science
2 Simulation in education and training
3 Examples in different areas
3.1 Truck Simulator
3.2 Healthcare (Clinical) Simulators

3.2.1 History of Simulation in Healthcare

3.2.1.1 Active models

3.2.1.2 Interactive models

3.2.1.3 Computer simulators

3.2.1.4 The "classroom of the future"
3.3 Finance
3.4 City Simulators / Urban Simulation
3.5 Flight simulators

3.5.1 Home-built Flight Simulators
3.6 Marine simulators
3.7 Engineering (Technology) simulation or Process simulation
4 Simulation and games
5 See also
6 References
7 Notes
8 External links
8.1 Organizations
8.2 Education
8.3 Wikimedia
[edit]
Classification and terminology
Historically, simulations used in different fields developed largely independently,
but 20th century studies of Systems theory and Cybernetics combined with
spreading use of computers across all those fields have led to some unification
and a more systematic view of the concept.
[edit]
Physical and interactive simulation
Physical simulation refers to simulation in which physical objects are substituted
for the real thing. These physical objects are often chosen because they are
smaller or cheaper than the actual object or system.
Interactive simulation is a special kind of physical simulation, often referred to as
a human in the loop simulation, in which physical simulations include human
operators, such as in a flight simulator or a driving simulator.
[edit]
Computer simulation
Main article: Computer simulation
A computer simulation is an attempt to model a real-life or hypothetical situation
on a computer so that it can be studied to see how the system works. By
changing variables, predictions may be made about the behaviour of the system.
An interesting application of computer simulation is to simulate computers using
computers. The related software is called computer architecture simulators,
which can be further divided into instruction set simulators or full system
simulators.
Computer simulation has become a useful part of modeling many natural
systems in physics, chemistry and biology, and human systems in economics
and social science (the computational sociology) as well as in engineering to
gain insight into the operation of those systems. A good example of the
usefulness of using computers to simulate can be found in the field of network
traffic simulation. In such simulations the model behaviour will change each
simulation according to the set of initial parameters assumed for the
environment. Computer simulations are often considered to be human out of the
loop simulations.
Traditionally, the formal modeling of systems has been via a mathematical
model, which attempts to find analytical solutions enabling the prediction of the
behaviour of the system from a set of parameters and initial conditions.
Computer simulation is often used as an adjunct to, or substitution for, modeling
systems for which simple closed form analytic solutions are not possible. There
are many different types of computer simulation, the common feature they all
share is the attempt to generate a sample of representative scenarios for a
model in which a complete enumeration of all possible states would be
prohibitive or impossible.
Various industries use discrete event simulation to model systems of interest in
commerce, health, defence, manufacturing, logistics etc., for example the valueadding business processes. Imagine a business, where each person could do
30 tasks, where thousands of products or services involved dozens of tasks in a
sequence, where customer demand varied seasonally and forecasting was
inaccurate — this is the domain where such simulation helps with business
decisions across all functions. Related topics include Theory of Constraints,
bottlenecks, and management consulting.
Several software packages exist for running computer-based simulation
modeling (e.g. Monte Carlo simulation and stochastic modeling) that makes the
modeling almost effortless.
It is increasingly common to hear simulations of many kinds referred to as
"synthetic environments". This label has been adopted to broaden the definition
of "simulation" to encompass virtually any computer-based representation.
[edit]
Simulation in computer science
In computer science, simulation has an even more specialized meaning: Alan
Turing uses the term "simulation" to refer to what happens when a digital
computer runs a state transition table (runs a program) that describes the state
transitions, inputs and outputs of a subject discrete-state machine. The
computer simulates the subject machine.
In computer architecture, a simulator is often used to execute a program that
has to run on some inconvenient type of computer, or in a tightly controlled
testing environment (see Computer architecture simulator). For example,
simulators are usually used to debug a microprogram or sometimes commercial
application programs. Since the operation of the computer is simulated, all of the
information about the computer's operation is directly available to the
programmer, and the speed and execution of the simulation can be varied at
will. Simulators may also be used to interpret fault trees, or test VLSI logic
designs before they are constructed. Symbolic simulation that uses variables to
stand for unknown values.
In theoretical computer science the term simulation represents a relation
between state transition systems. This is useful in the study of operational
semantics.
In the field of optimization, simulations of physical processes are often used in
conjunction with evolutionary computation to optimize control strategies.
[edit]
Simulation in education and training
EP-09 simulator
Simulation is often used in the training of civilian and military personnel. This
usually occurs when it is prohibitively expensive or simply too dangerous to
allow trainees to use the real equipment in the real world. In such situations they
will spend time learning valuable lessons in a "safe" virtual environment. Often
the convenience is to permit mistakes during training for a safety-critical system.
Training simulations typically come in one of three categories:
"live" simulation (where real people use simulated (or "dummy") equipment in
the real world);
"virtual" simulation (where real people use simulated equipment in a
simulated world (or "virtual environment")), or
"constructive" simulation (where simulated people use simulated equipment in
a simulated environment). Constructive simulation is often referred to as
"wargaming" since it bears some resemblance to table-top war games in which
players command armies of soldiers and equipment that move around a board.
Simulations in education are somewhat like training simulations. They focus on
specific tasks. In the past, video has been used for teachers and education
students to observe, problem solve and role play; however, a more recent use of
simulations in education include animated narrative vignettes (ANV). ANVs are
cartoon-like video narratives of hypothetical and reality-based stories involving
classroom teaching and learning. ANVs have been used to assess knowledge,
problem solving skills and dispositions of children, and pre-service and inservice teachers.
Another form of simulation has been finding favour in business education in
recent years. Business simulations that incorporate a dynamic model enables
experimentation with business strategies in a risk free environment and provide
a useful extension to case study discussions.
[edit]
Examples in different areas
[edit]
Truck Simulator
A soldier tests out a heavy-wheeled-vehicle driver simulator.
A truck simulator provides an opportunity to reproduce the characteristics of real
vehicles in a virtual environment. It replicates the external factors and conditions
with which a vehicle interacts enabling a driver to feel as if they are sitting in the
cab of their own vehicle. Scenarios and events are replicated with sufficient
reality to ensure that drivers become fully immersed in the experience rather
than simply viewing it as an educational programme.
The simulator provides a constructive experience for the novice driver and
enables more complex exercises to be undertaken by the more mature driver.
For novice drivers, truck simulators provide an opportunity to begin their career
by applying best practice. For mature drivers, simulation provides the ability to
enhance good driving or to detect poor practice and to suggest the necessary
steps for remedial action. For companies, it provides an opportunity to educate
staff in the driving skills that achieve reduced maintenance costs, improved
productivity and, most importantly, to ensure the safety of their actions in all
possible situations.
[edit]
Healthcare (Clinical) Simulators
Medical simulators are increasingly being developed and deployed to teach
therapeutic and diagnostic procedures as well as medical concepts and decision
making to personnel in the health professions. Simulators have been developed
for training procedures ranging from the basics such as blood draw, to
laparoscopic surgery and trauma care. They are also important to help on
prototyping new devices for biomedical engineering problems. Currently,
simulators are applied to research and development of tools for new therapies,
treatments and early diagnosis in medicine.
Many medical simulators involve a computer connected to a plastic simulation of
the relevant anatomy. Sophisticated simulators of this type employ a life size
mannequin that responds to injected drugs and can be programmed to create
simulations of life-threatening emergencies. In others simulations, visual
components of the procedure are reproduced by computer graphics techniques,
while touch-based components are reproduced by haptic feedback devices
combined with physical simulation routines computed in response to the user's
actions. Medical simulations of this sort will often use 3D CT or MRI scans of
patient data to enhance realism. Some medical simulations are developed to be
widely distributed (such as web-enabled simulations that can be viewed via
standard web browsers) and can be interacted with using standard computer
interfaces, such as the keyboard and mouse.
Another important medical application of a simulator — although, perhaps,
denoting a slightly different meaning of simulator — is the use of a placebo drug,
a formulation that simulates the active drug in trials of drug efficacy (see Placebo
(origins of technical term)).
[edit] History of Simulation in Healthcare
The first medical simulators were simple models of human patients.
Since antiquity, these representations in clay and stone were used to
demonstrate clinical features of disease states and their effects on humans.
Models have been found from many cultures and continents. These models
have been used in some cultures (e.g., Chinese culture) as a "diagnostic"
instrument, allowing women to consult male physicians while maintaining social
laws of modesty. Models are used today to help students learn the anatomy of
the musculoskeletal system and organ systems.
[edit] Active models
Active models that attempt to reproduce living anatomy or physiology are recent
developments.
The famous “Harvey” mannikin was developed at the University of Miami and is
able to recreate many of the physical findings of the cardiology examination,
including palpation, auscultation, and electrocardiography.
[edit] Interactive models
More recently, interactive models have been developed that respond to actions
taken by a student or physician. Until recently, these simulations were two
dimensional computer programs that acted more like a textbook than a patient.
Computer simulations have the advantage of allowing a student to make
judgements, and also to make errors. The process of iterative learning through
assessment, evaluation, decision making, and error correction creates a much
stronger learning environment than passive instruction.
[edit] Computer simulators
Simulators have been proposed as an ideal tool for assessment of students for
clinical skills.
Programmed patients and simulated clinical situations, including mock disaster
drills, have been used extensively for education and evaluation. These “lifelike”
simulations are expensive, and lack reproducibility. A fully functional "3Pi"
simulator would be the most specific tool available for teaching and
measurement of clinical skills.
Such a simulator meets the goals of an objective and standardized examination
for clinical competence. This system is superior to examinations that use
"standard patients" because it permits the quantitative measurement of
competence, as well as reproducing the same objective findings.
[edit] The "classroom of the future"
The "classroom of the future" will probably contain several kinds of simulators, in
addition to textual and visual learning tools. This will allow students to enter the
clinical years better prepared, and with a higher skill level. The advanced
student or postgraduate will have a more concise and comprehensive method of
retraining — or of incorporating new clinical procedures into their skill set — and
regulatory bodies and medical institutions will find it easier to assess the
proficiency and competency of individuals.
The classroom of the future will also form the basis of a clinical skills unit for
continuing education of medical personnel; and in the same way that the use of
periodic flight training assists airline pilots, this technology will assist
practitioners throughout their career.
The simulator will be more than a "living" textbook, it will become an integral a
part of the practice of medicine. The simulator environment will also provide a
standard platform for curriculum development in institutions of medical
education.
[edit]
Finance
Main article: Mathematical finance
In finance, computer simulations are often used for scenario planning. Riskadjusted net present value, for example, is computed from well-defined but not
always known (or fixed) inputs. By imitating the performance of the project under
evaluation, simulation can provide a distribution of NPV over a range of discount
rates and other inputs.
[edit]
City Simulators / Urban Simulation
A City Simulator can be a game but can also be a tool used by urban planners to
understand how cities are likely to evolve in response to various policy
decisions. UrbanSim (developed at the University of Washington), ILUTE
(developed at the University of Toronto) and Distrimobs (developed at the
University of Bologna) are examples of modern, large-scale urban simulators
designed for use by urban planners. City simulators are generally agent-based
simulations with explicit representations for land use and transportation.
[edit]
Flight simulators
Main article: Flight simulator
A flight simulator is used to train pilots on the ground. It permits a pilot to crash
his simulated "aircraft" without being hurt. Flight simulators are often used to
train pilots to operate aircraft in extremely hazardous situations, such as
landings with no engines, or complete electrical or hydraulic failures. The most
advanced simulators have high-fidelity visual systems and hydraulic motion
systems. The simulator is normally cheaper to operate than a real trainer
aircraft.
[edit] Home-built Flight Simulators
Main article: Flight simulator, Simulation Game
Some people who use simulator software, especially flight simulator software,
build their own simulator at home. Some people in order to further the realism of
their homemade simulator, buy used cards and racks that still run the exact
same software they did before they were disassembled from the actual machine
itself. Though this brings along the problem of matching hardware and software,
and the fact that hundreds of cards plug into many different racks, still, many find
that is it well worth it. Some are very serious in building their simulator by buying
real aircraft parts like complete nose sectionals of written off aircraft at aircraft
boneyards. This permits people who are unable to perform their hobby in real life
to simulate it.
[edit]
Marine simulators
Bearing resemblance to flight simulators, marine simulators train ships'
personnel. The most common marine simulators include:
Ship's bridge simulators
Engine room simulators
Cargo handling simulators
Communication / GMDSS simulators
Simulators like these are mostly used within maritime colleges and training
institutions. They often consist of a replication of a ships' bridge, with operating
desk(s), and a number of screens on which the virtual surroundings are
projected.
Engineering (Technology) simulation or Process
simulation
[edit]
Simulation is an important feature in engineering systems or any system that
involves many processes. For example in electrical engineering, delay lines may
be used to simulate propagation delay and phase shift caused by an actual
transmission line. Similarly, dummy loads may be used to simulate impedance
without simulating propagation, and is used in situations where propagation is
unwanted. A simulator may imitate only a few of the operations and functions of
the unit it simulates. Contrast with: emulate. (Source: Federal Standard 1037C)
Most engineering simulations entail mathematical modeling and computer
assisted investigation. There are many cases, however, where mathematical
modeling is not reliable. Simulation of fluid dynamics problems often require both
mathematical and physical simulations. In these cases the physical models
require dynamic similitude. Physical and chemical simulations have also direct
realistic uses, rather than research uses; in chemical engineering, for example,
process simulations are used to give the process parameters immediately used
for operating chemical plants, such as oil refineries.
[edit]
Simulation and games
Main article: Simulation game
Strategy games — both traditional and modern — may be viewed as simulations
of abstracted decision-making for the purpose of training military and political
leaders (see History of Go for an example of such a tradition). In a narrower
sense, many video games are also simulators, implemented inexpensively.
These are sometimes called "sim games". Such games can simulate various
aspects of reality, from economics to piloting vehicles, such as flight simulators
(described above). Another type of simulation is a government simulation, which
can be used to help the player understand certain aspects of political science —
specifically cause and effect.
[edit]
See also
Comparison of racing simulators
Monte Carlo simulation
Dissimulation
Molecular dynamics
Emulator
Network Simulator
Experimentation in silico
Placebo
Futures studies
Placebo (origins of technical term)
Mathematical model
Similitude (model)
Merger simulation
Simulated reality
Mining Simulation
Simulation language
Scientific modeling
[edit]
References
R. Frigg and S. Hartmann, Models in Science. Entry in the Stanford
Encyclopedia of Philosophy.
S. Hartmann, The World as a Process: Simulations in the Natural and Social
Sciences, in: R. Hegselmann et al. (eds.), Modelling and Simulation in the Social
Sciences from the Philosophy of Science Point of View, Theory and Decision
Library. Dordrecht: Kluwer 1996, 77–100.
P. Humphreys, Extending Ourselves: Computational Science, Empiricism,
and Scientific Method. Oxford: Oxford University Press, 2004.
Roger D. Smith: Simulation Article, Encyclopedia of Computer Science,
Nature Publishing Group, ISBN 0-333-77879-0.
Roger D. Smith: "Simulation: The Engine Behind the Virtual World", eMatter,
December, 1999.
Aldrich, C. (2003). Learning by Doing : A Comprehensive Guide to
Simulations, Computer Games, and Pedagogy in e-Learning and Other
Educational Experiences. San Francisco: Pfeifer — John Wiley & Sons.
Aldrich, C. (2004). Simulations and the future of learning: an innovative (and
perhaps revolutionary) approach to e-learning. San Francisco: Pfeifer — John
Wiley & Sons.
Percival, F., Lodge, S., Saunders, D. (1993). The Simulation and Gaming
Yearbook: Developing Transferable Skills in Education and Training. London:
Kogan Page.
South, R., "A Sermon Delivered at Christ-Church, Oxon., Before the
University, Octob. 14. 1688: Prov. XII.22 Lying Lips are abomination to the
Lord", pp.519–657 in South, R., Twelve Sermons Preached Upon Several
Occasions (Second Edition), Volume I, Printed by S.D. for Thomas Bennet,
(London), 1697.
Of Simulation and Dissimulation An essay by Francis Bacon.
Wolfe, Joseph & Crookall, David, (1998). Developing a scientific knowledge of
simulation/gaming . Simulation & Gaming: An International Journal of
Theory, Design and Research, 29(1), 7–19.
Bibliographies containing more references to be found on the website of the
journal Simulation & Gaming.
[edit]
1.
Notes
^ South, 1697, p.525.
South was speaking of the differences between a falsehood and an honestly
mistaken statement; the difference being that in order for the statement to be a
lie the truth must be known, and the opposite of the truth must have been
knowingly uttered.
And, from this, to the extent to which a lie involves deceptive words, a
simulation involves deceptive actions, deceptive gestures, or deceptive
behavior.
Thus, it would seem, if a simulation is false, then the truth must be known (in
order for something other than the truth to be presented in its stead); and, for the
simulation to simulate.
Because, otherwise, one would not know what to offer up in simulation.
Bacon’s essay Of Simulation and Dissimulation expresses somewhat similar
views; it is also significant that Samuel Johnson thought so highly of South's
definition, that he used it in the entry for simulation in his Dictionary of the
English Language.
[edit]
External links
Decision Makers - Internet based business Simulation
[edit]
Organizations
EUROSIM — Federation of European Simulation Societies
INFORMS Insitute for Operations Research and the Management Sciences
Institute for Simulation and Training, University of Central Florida
National Center for Simulation
Simulation Interoperability Standards Organization
The Society for Modeling and Simulation International (Formerly the Society
of Computer Simulation)
United States Defense Modeling and Simulation Office
Worldwide Simulation Organizations List
Winter Simulation Conference
See list of organisations provided by the journal S&G.
[edit]
Education
Nuclear Reactor Simulation - Includes the PC-based Boiling Water Reactor
Simulator Program.
IMTEK Mathematica Supplement (IMS) for open source simulation lectures
and packages.
Simulation — An Enabling Technology in Software Engineering
Simulation Education
Worldwide Simulation Course List
Clinical Training and Education Centre, University of Western Australia