A model is an informative representation of an object, person, or system. The term originally denoted the plans of a building in late 16th-century English, and derived via French and Italian ultimately from Latin modulus , a measure.
59-420: A simulation is an imitative representation of a process or system that could exist in the real world. In this broad sense, simulation can often be used interchangeably with model . Sometimes a clear distinction between the two terms is made, in which simulations require the use of models; the model represents the key characteristics or behaviors of the selected system or process, whereas the simulation represents
118-539: A flight simulator , sailing simulator , or driving simulator . Continuous simulation is a simulation based on continuous-time rather than discrete-time steps, using numerical integration of differential equations . Discrete-event simulation studies systems whose states change their values only at discrete times. For example, a simulation of an epidemic could change the number of infected people at time instants when susceptible individuals get infected or when infected individuals recover. Stochastic simulation
177-519: A microprogram or sometimes commercial application programs, before the program is downloaded to the target machine. 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 uses variables to stand for unknown values. In
236-427: A set of mathematical equations attempting to describe the workings of the atmosphere for the purpose of weather forecasting. It consists of concepts used to help understand or simulate a subject the model represents. Abstract or conceptual models are central to philosophy of science , as almost every scientific theory effectively embeds some kind of model of the physical or human sphere . In some sense,
295-411: 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. Model Models can be divided into physical models (e.g. a ship model or a fashion model) and abstract models (e.g. a set of mathematical equations describing the workings of
354-401: A "safe" virtual environment yet living a lifelike experience (or at least it is the goal). Often the convenience is to permit mistakes during training for a safety-critical system. Simulations in education are somewhat like training simulations. They focus on specific tasks. The term 'microworld' is used to refer to educational simulations which model some abstract concept rather than simulating
413-562: A National Agenda for Simulation-Based Medical Education (Eder-Van Hook, Jackie, 2004), "a health care provider's ability to react prudently in an unexpected situation is one of the most critical factors in creating a positive outcome in medical emergency, regardless of whether it occurs on the battlefield, freeway, or hospital emergency room." Eder-Van Hook (2004) also noted that medical errors kill up to 98,000 with an estimated cost between $ 37 and $ 50 million and $ 17 to $ 29 billion for preventable adverse events dollars per year. Simulation
472-494: 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 other 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
531-471: A great deal of promise for virtual simulations. Systems such as brain–computer interfaces (BCIs) offer the ability to further increase the level of immersion for virtual simulation users. Lee, Keinrath, Scherer, Bischof, Pfurtscheller proved that naïve subjects could be trained to use a BCI to navigate a virtual apartment with relative ease. Using the BCI, the authors found that subjects were able to freely navigate
590-474: A larger fixed scale vertically when modelling topography to enhance a region's mountains. An architectural model permits visualization of internal relationships within the structure or external relationships of the structure to the environment. Another use is as a toy . Instrumented physical models are an effective way of investigating fluid flows for engineering design. Physical models are often coupled with computational fluid dynamics models to optimize
649-409: A noun, model has specific meanings in certain fields, derived from its original meaning of "structural design or layout ": A physical model (most commonly referred to simply as a model but in this context distinguished from a conceptual model ) is a smaller or larger physical representation of an object , person or system . The object being modelled may be small (e.g., an atom ) or large (e.g.,
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#1732776679760708-401: A physical model "is always the reification of some conceptual model; the conceptual model is conceived ahead as the blueprint of the physical one", which is then constructed as conceived. Thus, the term refers to models that are formed after a conceptualization or generalization process. According to Herbert Stachowiak , a model is characterized by at least three properties: For example,
767-503: A realistic object or environment, or in some cases model a real-world environment in a simplistic way so as to help a learner develop an understanding of the key concepts. Normally, a user can create some sort of construction within the microworld that will behave in a way consistent with the concepts being modeled. Seymour Papert was one of the first to advocate the value of microworlds, and the Logo programming environment developed by Papert
826-404: 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. Patient safety is a concern in the medical industry. Patients have been known to suffer injuries and even death due to management error, and lack of using best standards of care and training. According to Building
885-566: A sponsor committee of the IEEE, promulgates improvements in DIS. Major changes occurred in the DIS 7 update to IEEE 1278.1 to make DIS more extensible, efficient and to support the simulation of more real world capabilities. Simulation state information is encoded in formatted messages, known as protocol data units (PDUs) and exchanged between hosts using existing transport layer protocols, including multicast , though broadcast User Datagram Protocol
944-653: A street map is a model of the actual streets in a city (mapping), showing the course of the streets while leaving out, say, traffic signs and road markings (reduction), made for pedestrians and vehicle drivers for the purpose of finding one's way in the city (pragmatism). Additional properties have been proposed, like extension and distortion as well as validity . The American philosopher Michael Weisberg differentiates between concrete and mathematical models and proposes computer simulations (computational models) as their own class of models. Distributed Interactive Simulation Distributed Interactive Simulation ( DIS )
1003-431: A type of simulator, typically called an emulator , is often used to execute a program that has to run on some inconvenient type of computer (for example, a newly designed computer that has not yet been built or an obsolete computer that is no longer available), or in a tightly controlled testing environment (see Computer architecture simulator and Platform virtualization ). For example, simulators have been used to debug
1062-666: Is a Federation Object Model (FOM) for the High-Level Architecture designed to organize the PDUs of DIS into an HLA object class and interaction class hierarchy. It has been developed as the SISO standard SISO-STD-001. The purpose is to support transition of legacy DIS systems to the HLA, to enhance a priori interoperability among RPR FOM users and to support newly developed federates with similar requirements. The most recent version
1121-439: Is a simulation where some variable or process is subject to random variations and is projected using Monte Carlo techniques using pseudo-random numbers. Thus replicated runs with the same boundary conditions will each produce different results within a specific confidence band. Deterministic simulation is a simulation which is not stochastic: thus the variables are regulated by deterministic algorithms. So replicated runs from
1180-461: Is also good evidence that procedural simulation improves actual operational performance in clinical settings." However, there is a need to have improved evidence to show that crew resource management training through simulation. One of the largest challenges is showing that team simulation improves team operational performance at the bedside. Although evidence that simulation-based training actually improves patient outcome has been slow to accrue, today
1239-411: Is also supported. There are several versions of the DIS application protocol, not only including the formal standards, but also drafts submitted during the standards balloting process. The current version (DIS 7) defines 72 different PDU types, arranged into 13 families. Frequently used PDU types are listed below for each family. PDU and family names shown in italics are found in DIS 7. The RPR FOM
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#17327766797601298-508: Is also used with scientific modelling of natural systems or human systems to gain insight into their functioning, as in economics. Simulation can be used to show the eventual real effects of alternative conditions and courses of action. Simulation is also used when the real system cannot be engaged, because it may not be accessible, or it may be dangerous or unacceptable to engage, or it is being designed but not yet built, or it may simply not exist. Key issues in modeling and simulation include
1357-642: Is an IEEE standard for conducting real-time platform-level wargaming across multiple host computers and is used worldwide, especially by military organizations but also by other agencies such as those involved in space exploration and medicine . The standard was developed over a series of "DIS Workshops" at the Interactive Networked Simulation for Training symposium, held by the University of Central Florida's Institute for Simulation and Training (IST). The standard itself
1416-402: Is being used to study patient safety, as well as train medical professionals. Studying patient safety and safety interventions in healthcare is challenging, because there is a lack of experimental control (i.e., patient complexity, system/process variances) to see if an intervention made a meaningful difference (Groves & Manges, 2017). An example of innovative simulation to study patient safety
1475-426: Is from nursing research. Groves et al. (2016) used a high-fidelity simulation to examine nursing safety-oriented behaviors during times such as change-of-shift report . However, the value of simulation interventions to translating to clinical practice are is still debatable. As Nishisaki states, "there is good evidence that simulation training improves provider and team self-efficacy and competence on manikins. There
1534-568: 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. Several software packages exist for running computer-based simulation modeling (e.g. Monte Carlo simulation, stochastic modeling, multimethod modeling) that makes all
1593-493: Is one of the most well-known microworlds. Project management simulation is increasingly used to train students and professionals in the art and science of project management. Using simulation for project management training improves learning retention and enhances the learning process. Social simulations may be used in social science classrooms to illustrate social and political processes in anthropology, economics, history, political science, or sociology courses, typically at
1652-436: Is one which uses more than one computer simultaneously, to guarantee access from/to different resources (e.g. multi-users operating different systems, or distributed data sets); a classical example is Distributed Interactive Simulation (DIS). Parallel simulation speeds up a simulation's execution by concurrently distributing its workload over multiple processors, as in high-performance computing . Interoperable simulation
1711-466: Is patient care to deliver just-in-time service or/and just-in-place. This training consists of 20 minutes of simulated training just before workers report to shift. One study found that just in time training improved the transition to the bedside. The conclusion as reported in Nishisaki (2008) work, was that the simulation training improved resident participation in real cases; but did not sacrifice
1770-522: Is used to describe the accuracy of a simulation and how closely it imitates the real-life counterpart. Fidelity is broadly classified as one of three categories: low, medium, and high. Specific descriptions of fidelity levels are subject to interpretation, but the following generalizations can be made: A synthetic environment is a computer simulation that can be included in human-in-the-loop simulations. Simulation in failure analysis refers to simulation in which we create environment/conditions to identify
1829-597: Is very closely patterned after the original SIMNET distributed interactive simulation protocol, developed by Bolt, Beranek and Newman (BBN) for Defense Advanced Research Project Agency (DARPA) in the early through late 1980s. BBN introduced the concept of dead reckoning to efficiently transmit the state of battle field entities. In the early 1990s, IST was contracted by the United States Defense Advanced Research Project Agency to undertake research in support of
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1888-469: Is where multiple models, simulators (often defined as federates) interoperate locally, distributed over a network; a classical example is High-Level Architecture . Modeling and simulation as a service is where simulation is accessed as a service over the web. Modeling, interoperable simulation and serious games is where serious game approaches (e.g. game engines and engagement methods) are integrated with interoperable simulation. Simulation fidelity
1947-481: The Solar System ) or life-size (e.g., a fashion model displaying clothes for similarly-built potential customers). The geometry of the model and the object it represents are often similar in the sense that one is a rescaling of the other. However, in many cases the similarity is only approximate or even intentionally distorted. Sometimes the distortion is systematic, e.g., a fixed scale horizontally and
2006-838: The US Army Simulator Network (SimNet) program. Funding and research interest for DIS standards development decreased following the proposal and promulgation of its successor, the High Level Architecture (simulation) (HLA) in 1996. HLA was produced by the merger of the DIS protocol with the Aggregate Level Simulation Protocol (ALSP) designed by MITRE . There was a NATO standardisation agreement ( STANAG 4482, Standardised Information Technology Protocols for Distributed Interactive Simulation (DIS) , adopted in 1995) on DIS for modelling and simulation interoperability. This
2065-410: The ability of simulation to provide hands-on experience that translates to the operating room is no longer in doubt. One of the largest factors that might impact the ability to have training impact the work of practitioners at the bedside is the ability to empower frontline staff (Stewart, Manges, Ward, 2015). Another example of an attempt to improve patient safety through the use of simulations training
2124-461: The acquisition of valid sources of information about the relevant selection of key characteristics and behaviors used to build the model, the use of simplifying approximations and assumptions within the model, and fidelity and validity of the simulation outcomes. Procedures and protocols for model verification and validation are an ongoing field of academic study, refinement, research and development in simulations technology or practice, particularly in
2183-418: The atmosphere for the purpose of weather forecasting). Abstract or conceptual models are central to philosophy of science . In scholarly research and applied science, a model should not be confused with a theory : while a model seeks only to represent reality with the purpose of better understanding or predicting the world, a theory is more ambitious in that it claims to be an explanation of reality. As
2242-408: The behaviour of the system under study. 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 (e.g., 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
2301-407: The cause of equipment failure. This can be the best and fastest method to identify the failure cause. A computer simulation (or "sim") 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 in the simulation, predictions may be made about the behaviour of the system. It is a tool to virtually investigate
2360-449: The design of equipment and processes. This includes external flow such as around buildings, vehicles, people, or hydraulic structures . Wind tunnel and water tunnel testing is often used for these design efforts. Instrumented physical models can also examine internal flows, for the design of ductwork systems, pollution control equipment, food processing machines, and mixing vessels. Transparent flow models are used in this case to observe
2419-457: The detailed flow phenomenon. These models are scaled in terms of both geometry and important forces, for example, using Froude number or Reynolds number scaling (see Similitude ). In the pre-computer era, the UK economy was modelled with the hydraulic model MONIAC , to predict for example the effect of tax rises on employment. A conceptual model is a theoretical representation of a system, e.g.
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2478-455: The evolution of the model over time. Another way to distinguish between the terms is to define simulation as experimentation with the help of a model. This definition includes time-independent simulations. Often, computers are used to execute the simulation . Simulation is used in many contexts, such as simulation of technology for performance tuning or optimizing, safety engineering , testing, training, education, and video games. Simulation
2537-438: 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. 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
2596-428: The field of optimization , simulations of physical processes are often used in conjunction with evolutionary computation to optimize control strategies. Simulation is extensively used for educational purposes. It is used for cases where 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
2655-424: 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 develop tools for new therapies, treatments and early diagnosis in medicine. Many medical simulators involve
2714-425: The high school or university level. These may, for example, take the form of civics simulations, in which participants assume roles in a simulated society, or international relations simulations in which participants engage in negotiations, alliance formation, trade, diplomacy, and the use of force. Such simulations might be based on fictitious political systems, or be based on current or historical events. An example of
2773-563: The latter would be Barnard College 's Reacting to the Past series of historical educational games. The National Science Foundation has also supported the creation of reacting games that address science and math education. In social media simulations, participants train communication with critics and other stakeholders in a private environment. In recent years, there has been increasing use of social simulations for staff training in aid and development agencies. The Carana simulation, for example,
2832-399: The modeling almost effortless. Modern usage of the term "computer simulation" may encompass virtually any computer-based representation. 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 (in modern terminology, a computer runs a program) that describes
2891-440: The norm in most military training processes and there is a significant amount of data to suggest this is a useful tool for armed professionals. A virtual simulation is a category of simulation that uses simulation equipment to create a simulated world for the user. Virtual simulations allow users to interact with a virtual world . Virtual worlds operate on platforms of integrated software and hardware components. In this manner,
2950-571: The quality of service. It could be therefore hypothesized that by increasing the number of highly trained residents through the use of simulation training, that the simulation training does, in fact, increase patient safety. 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 in many cultures and continents. These models have been used in some cultures (e.g., Chinese culture) as
3009-432: The real thing (some circles use the term for computer simulations modelling selected laws of physics, but this article does not). 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
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#17327766797603068-434: The same boundary conditions always produce identical results. Hybrid simulation (or combined simulation) corresponds to a mix between continuous and discrete event simulation and results in integrating numerically the differential equations between two sequential events to reduce the number of discontinuities. A stand-alone simulation is a simulation running on a single workstation by itself. A distributed simulation
3127-433: The state transitions, inputs and outputs of a subject discrete-state machine. The computer simulates the subject machine. Accordingly, in theoretical computer science the term simulation is a relation between state transition systems , useful in the study of operational semantics . Less theoretically, an interesting application of computer simulation is to simulate computers using computers. In computer architecture ,
3186-504: The system can accept input from the user (e.g., body tracking, voice/sound recognition, physical controllers) and produce output to the user (e.g., visual display, aural display, haptic display) . Virtual simulations use the aforementioned modes of interaction to produce a sense of immersion for the user. There is a wide variety of input hardware available to accept user input for virtual simulations. The following list briefly describes several of them: Research in future input systems holds
3245-433: 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 and procedural simulations that can be viewed via standard web browsers) and can be interacted with using standard computer interfaces, such as the keyboard and mouse . An important medical application of
3304-530: The virtual environment with relatively minimal effort. It is possible that these types of systems will become standard input modalities in future virtual simulation systems. There is a wide variety of output hardware available to deliver a stimulus to users in virtual simulations. The following list briefly describes several of them: Clinical healthcare simulators are increasingly being developed and deployed to teach therapeutic and diagnostic procedures as well as medical concepts and decision making to personnel in
3363-411: The work of computer simulation. 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. Physical simulation refers to simulation in which physical objects are substituted for
3422-549: Was first developed by the United Nations Development Programme , and is now used in a very revised form by the World Bank for training staff to deal with fragile and conflict-affected countries. Military uses for simulation often involve aircraft or armoured fighting vehicles, but can also target small arms and other weapon systems training. Specifically, virtual firearms ranges have become
3481-673: Was retired in favour of HLA in 1998 and officially cancelled in 2010 by the NATO Standardization Agency (NSA). DIS is defined under IEEE Standard 1278: In addition to the IEEE standards, the Simulation Interoperability Standards Organization (SISO) maintains and publishes an "enumerations and bit encoded fields" document yearly. This document is referenced by the IEEE standards and used by DIS, TENA and HLA federations. Both PDF and XML versions are available. SISO,
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