Glossary

API (Application Programming Interface)

A set of functions you use to control a specific service.

Co-simulation

A way to couple simulation models for performing transient simulation, by coupling the simulation environments (including their numerical solvers) themselves rather than the models directly.

DAE

Differential Algebraic Equation.

DAE index

The number of differentiation needed to reduce a DAE to an ODE.

Direct input-output dependency

A direct dependency is present if an output variable is defined by a mathematical expression in which an input variable appears explicitly.

DLL (Dynamic-Link Library)

DLL is Microsoft's implementation of the shared library concept in the Microsoft Windows and OS/2 operating systems. As with executables, a DLL file can contain code, data, and resources, in any combination. A function contained in a DLL cannot run on its own, it can only run from inside an executable file in which it was previously declared before being called (DLL function call).

Fixed-step solver

A numerical solver using numerical methods which integrate the differential equations of a dynamical system on a fixed periodic time basis, thus using the same step size during the simulation. Such a solver does not provide error control and does not locate zero crossings.

FMI

Functional Mockup Interface.

FMI for Co-simulation

The part of the FMI specification which describes a standard interface between two simulation environments.

FMI for Co-simulation environment

A simulation environment software which complies with the FMI for Co-simulation 1.0 specifications and is able to import an FMU for co-simulation, to connect it with a surrounding model or other FMUs, and finally to perform transient simulation of the whole coupled system through a co-simulation scheme.

FMI for Model Exchange

The part of the FMI specification which describes a standard interface between a model and a simulation environment.

FMU

Functional Mockup Unit, also known as FMU component.

Interface

An abstraction of a software component that describes its behavior without dealing with the internal implementation. Software components communicate with each other via interfaces.

Master simulator

In the Tool coupling scenario, a simulator that is able to import slave FMU for co-simulation, and performs co-simulation by applying the co-simulation time steps to the slaves. See FMI for Co-simulation environment.

Model Export

The process of exporting a model into a format that can be understood by another tool.

Modelica Compiler

The software tool which translates a Modelica source model into a C source code representing an executable version of a model.

Modelica Import Assistant

The module of the graphical user interface of Simcenter Amesim which uses the Modelica Compiler to produce a submodel from a Modelica source model.

Model Interface

An Application Programming Interface consisting of a set of standardized functions following the C-language call conventions. These functions allow a simulation environment to evaluate the equations of the system simulation model enclosed in a FMU.

MODELISAR

The ITEA2 (07006) research project in which framework the FMI specifications were developed.

ODE

Ordinary Differential Equation. An equation involving functions and their derivatives. The derivatives are with respect to one independent variable only. ODE is a relation that contains functions of only one independent variable, and one or more of their derivatives with respect to that variable. Compare to Partial Differential Equation (PDE)

Run parameters

The numerical solver related settings that can be changed by the user in the Run Parameters dialog box of Simcenter Amesim or at runtime by the FMI for Co-simulation environment.

Scalar variables

An elementary data of a FMU. This could be either a parameter, an ordinary variable or an input/output variable.

Simulation environment

A software environment generally made of a numerical solver, libraries and pre- and post-processing tools able to perform (at least) the transient simulation of a system model.

Slave FMU

An FMU for co-simulation which contains a slave simulator.

Slave simulator

A simulator which implements the FMI for co-simulation binary API, and executes time steps applied by a master simulator.

SPE file

An XML file which describes the interfaces of a submodel.

Start value

In the FMI for Model Exchange specification, scalar variables may have a start value which define their value prior to initialization. The start values stored in the FMU when it is generated by the Export Tool are used as default value if the simulation environment does not provide these values.

Variable Step Solver

A numerical solver, consisting in an integration method, an error estimator and a step size adaptation heuristics, which integrates the differential equations of a dynamical system by controlling the size of its numerical time steps to ensure that the truncation error is bounded by a given error tolerance value.