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What Exactly is a "Model?"

by zscott

People use the word model in many different ways. They might mean a fashion model or a model plane or a financial model. The kinds of models we focus on are those that "represent" some aspects of a physical reality. It might be the images that make up a model of the human body, or a plastic figure that contains representations of the major systems. It might be a scaled rendition of a plane or a ship or even a set of plans for a landscape design.

One way to describe the concept of model would be to see the model as a "hypothetical description of a complex entity or process." The plastic plane is a tangible description of the real thing. Models can be "literal" like a toy car that mimics the "real" automobile or they can lie anywhere along a spectrum from the literal representation to models that exist as a set of equations or simulations like a complex financial model.

For the purposes of systems engineering the system models that we consider lie at the symbolic end of the spectrum. In this sense we mean specifically models of systems or "systematic representations of systems." From an engineering perspective the model must span at least four domains (requirements, behavior, physical architecture, and verification & validation). It must also consider and describe the entire lifespan of the system from problem identification to the initial concept to retirement.

It is important to note that graphical representations standing alone are NOT the complete model. They express aspects of the model but, in our context they are not complete enough to be seen as models themselves. They are representations that derive from the model. Taken together they can give us a detailed picture of the model but they are not the model itself.

One of the critical aspects of a systems engineering model is that of relationships. In a global sense the system relates to the external world in a variety of ways that must be captured in the model. Internally the system components relate to each other. This is very similar to the global relationships of the model to the world around it. This becomes apparent when we think of a component as a "system" and the other components as "externals."

This is why the graphical representations are not sufficient to depict the system but must be webbed together with a "language" that expresses these concepts. The language sets up relationships between the system and its externals and between the internal system components. This makes the model robust and ultimately, executable. Without the relationships the most we can have are symbolic representations of the model.

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Categories: MBSE | Vitech


Expanded CORE Support Resources?

by bmaddox

Did you know that there are five ways to contact our Support Team? Yes, five! We want to be there for you in whatever format is most convenient for you. Let’s take a minute for me to give you the 411 on all the ways we are available. The first two are only available for customers who have a current maintenance contract. The rest are available to everyone.


First, if you are reading this blog post, then you found our Community site. Congrats on finding the webs newest resource for Systems Engineers! (Someday soon I hope to be able to say “the best resource!”) Check out the forums. There you will find a section for Priority CORE Support. Although other customers can post an answer to your question, we promise that someone from our Support Team will respond to every question.


It’s pretty much a standard these days to have Support via chat, and we have that too. Just log into the MySupport section of our website and you’ll find the chat option there. We’re logged in Monday through Friday 9-6 EST.


You can also reach us by submitting a webform. We have a Priority Support Request form in the MySupport section of the site and a standard Support Request form available to everyone.


We take email requests, too. It doesn’t seem that notable since everyone does it, but we promise to do it better!


And if you just like to hear my friendly voice, pick up the phone and call me. The direct line for support is 540-951-3999.


We want to hear from you! Let us know what works, what doesn’t, and what we can do to help you Make It Happen for your customers!

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Categories: CORE Software | Primer | Tips and Tricks | Vitech

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